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Characteristics of amplitude and duration for near fault strong ground motion from the 1999 Chi-Chi, Taiwan Earthquake
A great number of free-field ground motion records are obtained during the 1999 Chi-Chi, Taiwan, earthquake. Records from 130 near fault free-field stations within 55km to the causative fault surface are used as database, and characteristics of earthquake peak ground acceleration, velocity, displacement and duration are analyzed. According to this study, near fault ground motions are strongly affected by distance
G.-Q Wang; X.-Y Zhou; P.-Z Zhang; H Igel
The Development of Real-time Strong-motion Observation on the Earthquake Early Warning in Taiwan
NASA Astrophysics Data System (ADS)
For the sake of seismic hazards mitigation, a real-time strong-motion monitoring system was implemented by the Central Weather Bureau (CWB) since 1995. After successive refinements during the past decade, the system has been utilized as the basis for the development of the early warning (EWS) application in Taiwan. In order to shorten the earthquake response time, a virtual sub-network approach is utilized at first. Under the practical experiment since 2001, for monitoring inland or near offshore earthquakes with magnitude greater than 4.5, the response time can be shorten as 18.8+-3.8 sec averagely. Therefore, it can provide early warning before S-wave arrival for metropolitan areas located 60 km away from the epicenter. For the sake of further reducing the area of so-called blind-zone which cannot provide early warning, we also attempted to utilize vertical displacement records of P-wave as a basis to issue warnings. As results, we found that the amplitude 0.1 cm can be used as a criterion to judge if an earthquake above magnitude 6.0 is occurring in Taiwan Island. Furthermore, we also derived a set of frequency-based formulas simultaneously, which can be used to estimate earthquake magnitude rapidly. To combine the research results, and under the framework of real-time strong-motion observational network, we designed an earthquake early warning algorithm which is suitable for Taiwan Island. According to the experiment on 7 magnitude-above-6.0 earthquakes took place after 2002, the averaged response times is within 15 sec. Furthermore, the processing time for inland earthquakes can be shorten beneath 10 sec, and the radius of blind-zone is reduced to 30 km. Since 2003, the CWB has been replacing the existing 16-bit digital accelero- graphs used in its real-time strong-motion monitoring to 24-bit instruments at an annual replacement rate of 5 to 10% of the total. Besides, some high quality borehole seismic stations and a cable-based Ocean Bottom Seismographic (OBS) system are planed to implement on and off north-eastern Taiwan since 2007. We will further develop the EWS in response to these new instruments, as well as to any new research ideas.
Hsiao, N.; Shin, T.; Wu, Y.
Some observations on colocated and closely spaced strong ground-motion records of the 1999 Chi-Chi, Taiwan, earthquake
The digital accelerograph network installed in Taiwan produced a rich set of records from the 20 September 1999 Chi-Chi, Taiwan earthquake (Mw 7.6). Teledyne Geotech model A-800 and A-900A* digital accelerographs were colocated at 22 stations that recorded this event. Comparisons of the amplitudes, frequency content, and baseline offsets show that records from several of the A-800 accelerographs are considerably different than those from the colocated A-900A accelerographs. On this basis, and in view of the more thorough predeployment testing of the newer A-900A instruments, we recommend that the records from the A-800 instruments be used with caution in analyses of the mainshock and aftershocks. At the Hualien seismic station two A-900A and one A-800 instruments were colocated, along with a Global Positioning System instrument. Although the records from the two A-900A instruments are much more similar than those from a colocated A-800 instrument, both three-component records contain unpredictable baseline offsets, which produced completely unrealistic ground displacements derived from the accelerations by double integration, as do many of the strong-motion data from this event; the details of the baseline offsets differ considerably on the two three-component records. There are probably numerous sources of the baseline offsets, including sources external to the instruments, such as tilting or rotation of the ground, and sources internal to the instruments, such as electrical or mechanical hysteresis in the sensors. For the two colocated A-900A records at the Hualien seismic station, however, the differences in the baseline offsets suggest that the principal source is some transient disturbance within the instrument. The baseline offsets generally manifest themselves in the acceleration time series as pulses or steps, either singly or in combination. We find a 0.015-Hz low-cut filter can almost completely eliminate the effects of the baseline offsets, but then information regarding the permanent displacements is lost. The causative mechanisms of the baseline offsets are unknown presently. Hence, it is very difficult to recover the permanent displacements from the modern digital records, although for records close to large earthquakes, the signal-to-noise ratio should theoretically be adequate to obtain ground motions with periods of hundreds of seconds. This study reinforces our conclusion from previous studies that the sources of baseline offsets occurring in digital strong-motion records are very complex and often unpredictable, and that, therefore, it is difficult to remove the baseline effects to maximize the information content of the record. The baseline offsets only affect very long period motions (e.g., >20 sec), however, and therefore are of little or no engineering concern.
Wang, G. -Q.; Boore, D. M.; Igel, H.; Zhou, X. -Y.
Three-dimensional dense strong motion waveform inversion for the rupture process of the 1999 Chi-Chi, Taiwan, earthquake
NASA Astrophysics Data System (ADS)
We inverted the high-resolution spatiotemporal slip distribution of the 21 September 1999 Chi-Chi, Taiwan, earthquake utilizing data from densely distributed island-wide strong motion stations for a three-dimensional (3-D) fault geometry, and 3-D Green's functions calculations based upon parallel nonnegative least squares inversion. The 3-D fault geometry, consistent with high-resolution reflection profile, is determined from GPS inversion and aftershocks distribution. This 3-D fault model presents the dip angle gradually becoming shallower from south to north along the fault and near flat at the deeper portion of the fault. The 3-D Green's functions are calculated through numerical wavefield simulation from three-dimensional heterogeneous velocity structure derived from tomography studies. The Green's functions show significant azimuthal variations and suggest the necessity of lateral heterogeneity in velocity structure. Considering complex fault geometry and Green's functions in full 3-D scale, we invert the spatial/temporal slip distribution of the 1999 Chi-Chi earthquake using the best available and most densely populated strong motion waveform data. We perform the inversion under a parallel environment utilizing multiple-time window to manage the large data volume and source parameters. Results indicate that most slip occurred at the shallower portion of the fault above the decollement. Two major asperities are found, one in the middle of the fault and another one at the northern portion of the fault near the bend in the fault trace. The slip in the southern portion of the fault shows a relatively low slip rate with longer time duration, while the slip in the northern portion of the fault shows a large slip rate with shorter time duration. The synthetics explain the observations well for the island-wide distributed strong motion stations. This comprehensive study emphasizes the importance of realistic fault geometry, 3-D Green's functions, and parallel inversion technique in correctly accounting for both the detailed source rupture process and its relationship with the strong ground motion of this intense earthquake.
Lee, Shiann-Jong; Ma, Kuo-Fong; Chen, How-Wei
Strong Ground Motion Simulation of the 1999 Chi-Chi, Taiwan, Earthquake from a Realistic 3D Source and Crustal Structure
NASA Astrophysics Data System (ADS)
The strong ground motion records during the 1999 Chi-Chi, Taiwan, earthquake (Mw=7.6) show various characteristics at different sites in Taiwan. The goal of our study is to make a realistic 3D forward simulation of the strong-motion field based upon the kinetic source model obtained from an inversion study with identical 3D path effects. Considering complex fault geometry and Green's functions in full 3D scale, we invert the spatial/temporal slip distribution of the 1999 Chi-Chi earthquake using the best available and most densely populated strong motion waveform data. We perform the inversion by developed a parallel non-negative least squares (Parallel NNLS) program under a parallel environment utilizing multiple-time window to manage the large data volume and source parameters. Inversion results indicate that most slip occurred at the shallower portion of the fault above the decollement. Two major asperities are found, one in the middle of the fault, and another one at the northern portion of the fault near the bend in the fault trace. This 3D source model is then applied to the 3D wavefield forward simulation. Comparisons between the simulation results and observed waveforms from dense island-wide strong motion stations demonstrate that the fault geometry, lateral velocity variation and complex source rupture process greatly influence the distribution of strong ground shaking. The simulation has reproduced the heavy damage area that is mainly concentrated in the hanging wall, especially close to the surface break of the Chelungpu fault. The source directivity effect is also reproduced and shows serious shaking along the northward rupture direction. This comprehensive study emphasizes the importance of realistic fault geometry, 3D Green's functions, and parallel inversion technique in correctly accounting for both the detailed source rupture process and its relationship with the strong ground motion of this intense earthquake.
Lee, S.; Ma, K.; Chen, H.
Some Observations on Colocated and Closely Spaced Strong Ground-Motion Records of the 1999 Chi-Chi, Taiwan, Earthquake
Abstract The digital accelerograph network,installed in Taiwan produced a rich set of records from the 20 September 1999 Chi-Chi, Taiwan earthquake (Mw 7.6). Teledyne Geotech model A-800 and A-900A* digital accelerographs were colocated at 22 stations that recorded this event. Comparisons of the amplitudes, frequency content, and baseline offsets show that records from several of the A-800 accelero- graphs are
Guo-quan Wang; David M. Boore; Heiner Igel; Xi-yuan Zhou
GROUND MOTION ASSESSMENT BASED ON WEAK MOTION DATA IN TAIWAN Ground Motion Assessment Based on Weak Motion Data in Taiwan
NASA Astrophysics Data System (ADS)
In this study, we characterize the scaling of the ground motions for frequencies ranging between 0.25 and 5 Hz, obtaining results for seismic attenuation, geometrical spreading, and source parameters in Taiwan. We regressed this large number of weak-motion data in order to characterize the regional propagation and the absolute source scaling. Stochastic simulations are generated for finite-fault ruptures using the obtained parameters to predict the absolute peaks of the ground acceleration and velocity for several magnitude and distance range, as well as beyond the magnitude range of the weak-motion data set on which they are calculated. The predictions are then compared with recorded strong motion data and empirical ground motion prediction equation obtained for the study region. We showed that our regional parameters, obtained from independent weak-motion database, may be applied for evaluation of ground motion parameters for earthquakes of magnitude up to 7.6.
Akinci, A.; D'Amico, S.; Malagnini, L.
Imaging source slip distribution by the back-projection of P-wave amplitudes from strong-motion records: a case study for the 2010 Jiasian, Taiwan, earthquake
NASA Astrophysics Data System (ADS)
We propose an approach to imaging earthquake source rupture process by direct back-projection of local high-frequency (0.1-2.5 Hz) P-wave displacements from strong-motion records. A series of synthetic experiments are performed which demonstrate that our approach is capable of recovering the spatial-temporal distribution of the source slip with a good station coverage and a high average coherence value between the target and template waveforms. We demonstrate the effectiveness of our approach by applying it to image the slip distribution of an earthquake occurred on 2010 March 4, in Jiasian (Mw = 6.0 and ML = 6.4) in southern Taiwan. The resulting moment-rate amplitude images show that the source rupture initiated at the vicinity of the hypocentre, followed by a moderate moment-rate release to the southeast of the hypocentre and a subsequent upward propagation, and finally propagated in the northwest direction, in agreement with the distribution of aftershocks. The majority of the slip at 17-20 km depth occurred to the west of the hypocentre, in a general agreement with the slip distributions obtained from dislocation model and finite-fault inversions. Our modified back-projection approach relies on seismic waveforms with the considerations of a recent 3-D structure model, high average coherence value, station correction factor and simplified amplitude correction. It is computationally efficient and allows for near real-time determinations of source slip distributions after earthquakes using strong-motion records. A quick result for the rupture model can be used in the calculation of strong ground-motion, providing important, useful and timely information for seismic hazard mitigation.
Chao, Wei-An; Zhao, Li; Wu, Yih-Min; Lee, Shiann-Jong
NSDL National Science Digital Library
Processed by Dr. Walt Silva of Pacific Engineering and supported by the Pacific Earthquake Engineering Research Center (PEER) at the University of California Berkley, the PEER Strong Motion Database "contains 1557 records from 143 earthquakes from tectonically active regions." Searches can be done by earthquake, type of plate movement (e.g., strike slip), magnitude, and several other criteria. The correct browser and JAVA version even allows dynamic sorting and interactive plotting of data.
Imaging the Rupture Front and Slip Distribution by the Back-projection of P-wave Amplitude from Strong-motion Records: A Case Study for the 2010 Jiasian, Taiwan, Earthquake
NASA Astrophysics Data System (ADS)
We propose a new approach of imaging earthquake source rupture process by direct back-projection of local P-wave displacement in strong-motion records. This approach is applied to estimate the slip distribution of an earthquake occurred in March 4, 2010, in Jiasian in southern Taiwan. Hypocenter of the Jiasian earthquake (Mw=6.0 and ML=6.4) is located at 22.96�N and 120.70�E with a focal depth of 23 km. Source imaging result shows that the rupture initiated from the hypocenter, and then a relatively small slip occurred in the northern part of the fault zone, and final propagated in the northwestern direction, in agreement with the distribution of aftershocks. Majority of the slip occurred in the western part of the epicenter, consistent with the dislocation model obtained from geodetic observations. This approach is computationally efficient and automatic. It allows for rapid determination of rupture front propagation and slip distribution after earthquakes using real-time strong-motion records, and provides important and useful information for seismic hazard mitigation.
Chao, W.; Zhao, L.; Wu, Y.
Most instruments used in seismological practice to record ground motion are pendulum seismographs, velocigraphs, or accelerographs. In most cases it is assumed that seismic instruments are only sensitive to the translational motion of the instrument's base. In this study the full equation of pendulum motion, including the inputs of rotations and tilts, is considered. It is shown that tilting the accelerograph's base can severely impact its response to the ground motion. The method of tilt evaluation using uncorrected strong-motion accelerograms was first suggested by Graizer (1989), and later tested in several laboratory experiments with different strong-motion instruments. The method is based on the difference in the tilt sensitivity of the horizontal and vertical pendulums. The method was applied to many of the strongest records of the Mw 6.7 Northridge earthquake of 1994. Examples are shown when relatively large tilts of up to a few degrees occurred during strong earthquake ground motion. Residual tilt extracted from the strong-motion record at the Pacoima Dam-Upper Left Abutment reached 3.1?? in N45??E direction, and was a result of local earthquake-induced tilting due to high-amplitude shaking. This value is in agreement with the residual tilt measured by using electronic level a few days after the earthquake. The method was applied to the building records from the Northridge earthquake. According to the estimates, residual tilt reached 2.6?? on the ground floor of the 12-story Hotel in Ventura. Processing of most of the strongest records of the Northridge earthquake shows that tilts, if happened, were within the error of the method, or less than about 0.5??.
Graizer, V.
Analysis of Near-Source Waves: Separation of Wave Types Using Strong Motion Array Recordings.
National Technical Information Service (NTIS)
Algorithms are developed for the separation and identification of seismic wave types in the near-source region. Two large earthquakes recorded by over twenty-five digital, three component accelerometers that make up SMART 1 (Strong Motion Array Taiwan 1),...
R. B. Darragh
Predictions of high-frequency ground-motion in Taiwan based on weak motion data
NASA Astrophysics Data System (ADS)
Following a recent paper we use weak-motion waveforms to calibrate a model for the prediction of earthquake-induced ground-motion in Taiwan, in the 0.25-5.0 Hz frequency range, valid up to Mw 7.6. The excitation/attenuation model is given in terms of frequency-dependent seismic wave attenuation, Qs(f), geometrical spreading, g(r), a magnitude-dependent stress parameters ?? for the excitation terms, and a site term for each seismic station used in the study. A set of weak-motion data was gathered from about 170 aftershocks of the Chi-Chi earthquake, Mw 7.6, of 1999 September 20, (17:47 UTC), recorded by 10 broad-band seismic stations. The moment magnitudes of the registered aftershocks ranged from Mw 3.0 to 6.5, and the hypocentral distances from a few kilometres to about 250 km. A frequency-dependent crustal quality factor, Q(f) = 350f0.32, was obtained, to be coupled with the geometrical spreading function
D'Amico, Sebastiano; Akinci, Aybige; Malagnini, Luca
A Strong-motion catalog for Indonesia
NASA Astrophysics Data System (ADS)
Since the Indonesian islands of Sumatra and Java lie adjacent to an active subduction zone and include some of the world's most densely populated areas, the reduction of potential earthquake fatalities through improved building codes and seismic hazard assessments is a high priority. One of the most critical parts of an earthquake hazard assessment is a quantitative description of the level of ground motion generated by an earthquake, also known as Ground Motion Prediction Equations (GMPEs). We have developed a strong ground motion database for of Sumatra and Java. This catalog includes: best-available earthquake catalogue parameters; a compilation of site response information using various techniques; and ground motion parameters commonly used in seismology and engineering applications, such as response spectra. We will show how the database can be used for investigating which published Ground Motion Prediction Equation (GMPE) are appropriate to use for Indonesian earthquake hazard assessment.
Rudyanto, A.; Cummins, P. R.; Ghasemi, H.; Gunawan, I.; Sukanta, N.; Suhardjono, S.
Empirical prediction of strong ground motion
In 1982, we published equations for the prediction of various measures of ground motion as a function of earthquake magnitude, distance from the earthquake rupture, and site geology. Many more strong-motion recordings have been obtained since we published our equations. The predictions of the ground motions from our published equations are in reasonable agreement with the peak accelerations from the new data. The increased number of data, however, allow us to refine our predictions for some regions of magnitude and distance space, and perhaps for other variables.
Boore, David, M.; Joyner, William, B.
National Strong-Motion Program Data Sets
NSDL National Science Digital Library
The US Geological Survey National Strong-Motion Program (NSMP) Data Sets Web site contains three informative and helpful digital data compilations. These include the Digitized Strong-Motion Accelerograms of North and Central American Earthquakes 1933-1986, which is a collection of 1,477 three-component station recordings from nearly 500 earthquakes. The second is the National Strong-Motion Network (NSMN) Accelerograms data set that has time series data recorded by NSMN stations for selected earthquakes since 1989. Lastly, there is the General Earthquake Observation System (GEOS) Accelerograms, which has recordings collected by the NSMP GEOS project for aftershock studies, long-term deployments, and short-term experiments. Each can easily be accessed via the main site and contain updated information from as recently as an April 22, 2003 California event.
The Italian Strong Motion Network (RAN)
NASA Astrophysics Data System (ADS)
A network for the strong motion monitoring of the territory allows recording data that provide an excellent opportunity to study the source, path, and site effects on the ground motions, specifically in near source area, for updating seismic hazard map and consequently construction codes and earthquake resistant design. Strong motion data also help to increase the effective preparation and response to seismic emergencies and the ability of a community to quickly recover from the damages of an earthquake contributes to lower the seismic risk usually measured in term of casualties and economic losses. The Italian network for monitoring the strong movement of the national territory (RAN) is the result of a fruitful cooperation over the last 16 years between the Italian government, the regions and local authorities and now counts more than 500 stations. Over the years, as a priority the DPC has focused mainly on the expansion of the network in terms of the number of measurement points and technological improvement of instrumentation as well as the data transmission system. A data acquisition centre was implemented in which the Antelope software collects, processes and archives, automatically, the data of the RAN and of the external strong motion networks that contribute to the database of the RAN. Recently the DPC has dedicated specific resources to improve the response of the network, in particular, in case of emergency. The efficiency of the network on a daily basis is not less than 95% and temporary networks were installed in the epicentral area within 24 hours after the earthquake and connected to the data acquisition centre in Rome. A fast seismic data analysis is essential to provide useful information to Authorities which make decisions immediately after a strong earthquake occurrence. During a strong earthquake, the modern accelerometers are the only instruments which can provide near source high-quality data that are important both for scientific and for civil protection purposes. Automatic and fast techniques have been developed by the University of Trieste for the automatic real-time strong motion data analysis. These techniques have been installed and customized in the data acquisition centre of the Department of Civil Protection of Italy (DPC) to process the quasi real-time data of the Italian Strong Motion Network (RAN) and to exploit information from RAN stations during seismic emergences for Civil protection purposes. RAN counts more than 500 stations covering all the Italian territory. Two local networks, the Friuli Venezia Giulia Accelerometric Network (RAF), located in NE Italy, and the Irpinia Seismic Network (ISNet), contribute their data into the RAN data acquisition system. The performance of the network and of the fast automatic strong motion data analysis during the Emilia 2012 sequence is analyzed.
Costa, Giovanni; Ammirati, Alfredo; de Nardis, Rita; Filippi, Luisa; Gallo, Antonella; Lavecchia, Giusy; Sirignano, Sebastiano; Zambonelli, Elisa; Nicoletti, Mario
Catalog of Strong-Motion Seismograph Stations and Records.
National Technical Information Service (NTIS)
The catalog lists all strong-motion accelerographs which are part of the National Strong-Motion Instrumentation Network managed by Seismic Engineering, USGS, for the National Science Foundation. The National Strong-Motion Instrumentation Network consists ...
R. J. Brazee
Strong motion monitoring in Canada has undergone significant changes in recent years. Most analogue, non-communicating instruments have been replaced with modern digital instruments that provide information in real-time. Dense networks are being deployed in the urban centres of southwest British Columbia to provide shaking parameters and \\
J. F. Cassidy; A. Rosenberger; G. C. Rogers; T. E. Little; J. Toth; J. Adams; P. Munro; S. Huffmann; J.-R. Pierre; H. Asmis; G. Pernica
Earthquake Scaling and Development of Ground Motion Prediction for Earthquake Hazard Mitigation in Taiwan
NASA Astrophysics Data System (ADS)
For earthquake hazard mitigation toward risk management, integration study from development of source model to ground motion prediction is crucial. The simulation for high frequency component ( > 1 Hz) of strong ground motions in the near field was not well resolved due to the insufficient resolution in velocity structure. Using the small events as Green's functions (i.e. empirical Green's function (EGF) method) can resolve the problem of lack of precise velocity structure to replace the path effect evaluation. If the EGF is not available, a stochastic Green's function (SGF) method can be employed. Through characterizing the slip models derived from the waveform inversion, we directly extract the parameters needed for the ground motion prediction in the EGF method or the SGF method. The slip models had been investigated from Taiwan dense strong motion and global teleseismic data. In addition, the low frequency ( < 1 Hz) can obtained numerically by the Frequency-Wavenumber (FK) method. Thus, broadband frequency strong ground motion can be calculated by a hybrid method that combining a deterministic FK method for the low frequency simulation and the EGF or SGF method for high frequency simulation. Characterizing the definitive source parameters from the empirical scaling study can provide directly to the ground motion simulation. To give the ground motion prediction for a scenario earthquake, we compiled the earthquake scaling relationship from the inverted finite-fault models of moderate to large earthquakes in Taiwan. The studies show the significant involvement of the seismogenic depth to the development of rupture width. In addition to that, several earthquakes from blind fault show distinct large stress drop, which yield regional high PGA. According to the developing scaling relationship and the possible high stress drops for earthquake from blind faults, we further deploy the hybrid method mentioned above to give the simulation of the strong motion in displacement, velocity and acceleration. We now give this exercise to the high stress drop event, and the events, which might have potential seismic hazard to a specific site to give further estimation on seismic hazard evaluation.
Ma, K.; Yen, Y.
Thermally driven motion of strongly heated fluids
NASA Astrophysics Data System (ADS)
Two sets of approximate equations governing the thermally driven motions of strongly heated fluids are derived by a formal and unified method, taking into account the fluid properties' temperature dependence. After considering the limits of strongly heated shallow and deep fluids, attention is given to weakly heated cases. The resulting equations constitute the Boussinesq approximation, and are valid independent of the relative magnitudes of the nondimensionalized depth of the fluid and the strength of the heat source distribution. In addition, all of the equations are based on a characteristic velocity that is vanishingly small when compared with the speed of sound.
de Boer, P. C. T.
Evaluation of Turkish National Strong Ground Motion Network Database
NASA Astrophysics Data System (ADS)
The strong ground motion records archieved in the Turkish National Strong Ground Motion Network database and Kandilli Observatory and Earthquake Research Institute Strong Ground Motion Network database have been analysed in order to extract some regional characterisitics of the records and to evaluate existing attenuation relationships. The strong ground motion data of (M2.2-M7.4) earthquakes recorded from 1976 to 2007 have been analysed and engineering parameters extracted. The engineering parameters obtained from the process include peak ground motion parameters such as PGA, PGV, PGD, spectral parameters such as Sa, Sd, ground motion duration and intensity estimations. In total 6762(2254 x 3) strong ground motion records with epicentral distance varying from 8.7km to 250km have been studied. The calculated parameters have been used in the evaluation and comparision of ground motion prediction equations which are used in the formation of real-time ground motion parameters and intensity maps.
Zulfikar, C.; Kamer, Y.; Erdik, M. O.
Strong Motion Seismograph Based On MEMS Accelerometer
NASA Astrophysics Data System (ADS)
The MEMS strong motion seismograph we developed used the modularization method to design its software and hardware.It can fit various needs in different application situation.The hardware of the instrument is composed of a MEMS accelerometer,a control processor system,a data-storage system,a wired real-time data transmission system by IP network,a wireless data transmission module by 3G broadband,a GPS calibration module and power supply system with a large-volumn lithium battery in it. Among it,the seismograph's sensor adopted a three-axis with 14-bit high resolution and digital output MEMS accelerometer.Its noise level just reach about 99?g/?Hz and �2g to �8g dynamically selectable full-scale.Its output data rates from 1.56Hz to 800Hz. Its maximum current consumption is merely 165?A,and the device is so small that it is available in a 3mm�3mm�1mm QFN package. Furthermore,there is access to both low pass filtered data as well as high pass filtered data,which minimizes the data analysis required for earthquake signal detection. So,the data post-processing can be simplified. Controlling process system adopts a 32-bit low power consumption embedded ARM9 processor-S3C2440 and is based on the Linux operation system.The processor's operating clock at 400MHz.The controlling system's main memory is a 64MB SDRAM with a 256MB flash-memory.Besides,an external high-capacity SD card data memory can be easily added.So the system can meet the requirements for data acquisition,data processing,data transmission,data storage,and so on. Both wired and wireless network can satisfy remote real-time monitoring, data transmission,system maintenance,status monitoring or updating software.Linux was embedded and multi-layer designed conception was used.The code, including sensor hardware driver,the data acquisition,earthquake setting out and so on,was written on medium layer.The hardware driver consist of IIC-Bus interface driver, IO driver and asynchronous notification driver. The application program layer mainly concludes: earthquake parameter module, local database managing module, data transmission module, remote monitoring, FTP service and so on. The application layer adopted multi-thread process. The whole strong motion seismograph was encapsulated in a small aluminum box, which size is 80mm�120mm�55mm. The inner battery can work continuesly more than 24 hours. The MEMS accelerograph uses modular design for its software part and hardware part. It has remote software update function and can meet the following needs: a) Auto picking up the earthquake event; saving the data on wave-event files and hours files; It may be used for monitoring strong earthquake, explosion, bridge and house health. b) Auto calculate the earthquake parameters, and transferring those parameters by 3G wireless broadband network. This kind of seismograph has characteristics of low cost, easy installation. They can be concentrated in the urban region or areas need to specially care. We can set up a ground motion parameters quick report sensor network while large earthquake break out. Then high-resolution-fine shake-map can be easily produced for the need of emergency rescue. c) By loading P-wave detection program modules, it can be used for earthquake early warning for large earthquakes; d) Can easily construct a high-density layout seismic monitoring network owning remote control and modern intelligent earthquake sensor.
Teng, Y.; Hu, X.
Attention in this discussion of Taiwan is directed to the following: geography; the people -- education, languages, religions, and cultural background; history; administration; political conditions; the economy; defense; foreign relations; and relations between the US and Taiwan. In 1987 the population was estimated to be 19.7 million with an annual growth rate of 1.07%. The infant mortality rate in 1986 was 0.7% with a life expectancy of 70.8 for men and 75.8 for women. Taipei, which continues its claim of sovereignty over all of China in the name of the "Republic of China," exercises control only over the island of Taiwan, the Penghu Islands, and about 20 offshore islands, most near the China mainland. Most native Taiwanese speak a variant of the Amoy (Hokkien) dialect of Southern Fujian. The predominant religion is a combination of Buddhism and Taoism. Chinese sources show migration to Taiwan began as early as A.D. 500. Dutch traders 1st claimed the island in 1624 as a base for Dutch commerce with Japan and the China coast. The 1st major influx of migrants from the Chinese mainland came during the Dutch period. In 1664, a Chinese fleet led by the Ming loyalist Zheng Chenggong retreated from the mainland and occupied Taiwan. Zheng expelled the Dutch and established Taiwan as a base in his attempt to restore the Ming Dynasty. After his death in 1683, his successors submitted to Manchu control. Manchu China ruled Taiwan as a frontier district until it was declared a separate Chinese province in 1886. The authorities in Taipei claim to be the government of all China, including Taiwan. When President Chiang Ching-kuo died in 1988, he was succeeded by Vice President Lee Teng-hui, who had been elected along with Chiang by the National Assembly to a 6-year term. Until 1986, Taiwan's political system was effectively 1 party. Before elections in 1986, many "nonpartisans" grouped together to form Taiwan's 1st new political party in over 4 decades -- the Democratic Progressive Party. Friction between mainlanders and native Taiwanese continues to be a problem, but it has abated with time and the gradual melding of the 2 Chinese communities. Taiwan has changed from an agricultural to an industrialized economy over the past 30 years. During 1973-82, the gross domestic product rose at an annual average of 9.5% in real terms. President Carter signed into law on April 10, 1979, the Taiwan Relations Act, which created domestic legal authority for the conduct of unofficial relations with Taiwan. PMID:12177975
The Commercial TREMOR Strong-Motion Seismograph
NASA Astrophysics Data System (ADS)
The emergence of major seismological and earthquake-engineering problems requiring large, dense instrument arrays led several of us to investigate alternate solutions. Evans and Rogers (USGS Open File Report 95-555, 1995) and Evans (USGS Open File Report 98-109, 1998) demonstrated the efficacy of low-cost robust silicon accelerometers in strong-motion seismology, making possible a vast increase in the spatial density of such arrays. The 1998 design displays true 16-bit performance and excellent robustness and linearity---13 of these prototype near-real-time instruments are deployed in Oakland, California, and have recorded data from seven small events (up to 5.7 %g). Since this technology is a radical departure from past efforts, it was necessary for the USGS to develop the sensor and demonstrate its efficacy thoroughly. Since it is neither practical nor appropriate for the USGS to produce instrumentation beyond a demonstration phase, the US Geological Survey and GeoSIG Ltd undertook a collaborative effort (a ``CRAD'') to commercialize the new technology. This effort has resulted in a fully temperature-compensated 16-bit system, the GeoSIG GT-316, announced in April, 2001, combining the ICS-3028 TM-based USGS sensor, temperature compensation technique, and peak ground velocity (PGV) computation with a highly customized 16-bit GeoSIG recorder. The price has not been set but is likely to be around \\2000 in large quantities. The result is a near-real-time instrument telemetering peak ground acceleration (PGA) and PGV about 90 s after onset of the P wave, then minutes later transmitting the waveform. The receiving software, ``HomeBase()'', also computes spectral acceleration, S_{a}. PGA, PGV, S_{a}, and waveforms are forwarded immediately by HomeBase() for ShakeMap generation and other uses. Shaking metrics from the prototypes in Oakland are consistently among the first to arrive for the northern California ShakeMap. For telemetry we use a low-cost always-connected cell-phone-based Internet technology (CDPD), but any RS-232 connected telemetry system is a viable candidate (spread spectrum, CDMA, GSM, POT). The instruments can be synchronized via CDPD to a few tenths of a second, or to full precision with an optional GPS receiver. Sensor RMS noise is 33 \\mathrm \\mu g over the band 0.1 to 35 Hz, 11 \\mathrm \\mu g$ over the band 0.1 to 1.0 Hz; the sensor is extremely linear (far better than 1% of full scale); temperature compensation is to better than 1% of full scale. TREMOR-class instruments are intended to fill the niche of high spatial resolution with an economical low-maintenance device, while conventional instruments continue to pursue maximum amplitude resolution. The TREMOR instrument also has applications in areas where budget or access limitations require lower purchase, installation, or maintenance cost (commercial ANSS partners, remote sites, on-call aftershock arrays, extremely dense arrays, and organizations with limited budgets). However, we primarily envision large, mixed arrays of conventional and TREMOR instruments in urban areas, the former providing better early information from small events and the TREMOR instruments guaranteeing better spatial resolution and more near-field recording of large events. Together, they would meet the ANSS goal of dense near-real-time urban monitoring and the collection of requisite data for risk mitigation.
Evans, J. R.; Hamstra, R. H.; Kuendig, C.; Camina, P.
Parallel PSM/FDM Hybrid Simulation of Ground Motions from the 1999 Chi-Chi, Taiwan, Earthquake
NASA Astrophysics Data System (ADS)
A new technique for the parallel computing of 3-D seismic wave propagation simulation is developed by hybridizing the Fourier pseudospectral method (PSM) and the finite-difference method (FDM). This PSM/FDM hybrid offers a good speed-up rate using a large number of processors. To show the feasibility of the hybrid, a numerical 3-D simulation of strong ground motion was conducted for the 1999 Chi-Chi, Taiwan earthquake (Mw 7.6). Comparisons between the simulation results and observed waveforms from a dense strong ground motion network in Taiwan clearly demonstrate that the variation of the subsurface structure and the complex fault slip distribution greatly affect the damage during the Chi-Chi earthquake. The directivity effect of the fault rupture produced large S-wave pulses along the direction of the rupture propagation. Slips in the shallow part of the fault generate significant surface waves in Coastal Plain along the western coast. A large velocity gradient in the upper crust can propagate seismic waves to longer distances with minimum attenuation. The S waves and surface waves were finally amplified further by the site effect of low-velocity sediments in basins, and caused the significant disasters.
Furumura, T.; Koketsu, K.; Wen, K.-L.
Towards an integrated European strong motion data distribution
NASA Astrophysics Data System (ADS)
Recent decades have seen a significant increase in the quality and quantity of strong motion data collected in Europe, as dense and often real-time and continuously monitored broadband strong motion networks have been constructed in many nations. There has been a concurrent increase in demand for access to strong motion data not only from researchers for engineering and seismological studies, but also from civil authorities and seismic networks for the rapid assessment of ground motion and shaking intensity following significant earthquakes (e.g. ShakeMaps). Aside from a few notable exceptions on the national scale, databases providing access to strong motion data has not appeared to keep pace with these developments. In the framework of the EC infrastructure project NERA (2010 - 2014), that integrates key research infrastructures in Europe for monitoring earthquakes and assessing their hazard and risk, the network activity NA3 deals with the networking of acceleration networks and SM data. Within the NA3 activity two infrastructures are being constructed: i) a Rapid Response Strong Motion (RRSM) database, that following a strong event, automatically parameterises all available on-scale waveform data within the European Integrated waveform Data Archives (EIDA) and makes the waveforms easily available to the seismological community within minutes of an event; and ii) a European Strong Motion (ESM) database of accelerometric records, with associated metadata relevant to earthquake engineering and seismology research communities, using standard, manual processing that reflects the state of the art and research needs in these fields. These two separate repositories form the core infrastructures being built to distribute strong motion data in Europe in order to guarantee rapid and long-term availability of high quality waveform data to both the international scientific community and the hazard mitigation communities. These infrastructures will provide the access to strong motion data in an eventual EPOS seismological service. A working group on Strong Motion data is being created at ORFEUS in 2013. This body, consisting of experts in strong motion data collection, processing and research from across Europe, will provide the umbrella organisation that will 1) have the political clout to negotiate data sharing agreements with strong motion data providers and 2) manage the software during a transition from the end of NERA to the EPOS community. We expect the community providing data to the RRSM and ESM will gradually grow, under the supervision of ORFEUS, and eventually include strong motion data from networks from all European countries that can have an open data policy.
Luzi, Lucia; Clinton, John; Cauzzi, Carlo; Puglia, Rodolfo; Michelini, Alberto; Van Eck, Torild; Sleeman, Reinhoud; Akkar, Sinan
Seismic Response of a Sedimentary Basin: Preliminary Results from Strong Motion Downhole Array in Taipei Basin
NASA Astrophysics Data System (ADS)
The Strong Motion Downhole Array (SMDA) is an array of 32 triggered strong motion broadband seismometers located at eight sites in Taipei Basin. Each site features three to five co-located three-component accelerometers--one at the surface and an additional two to four each down independent boreholes. Located in the center of Taipei Basin is Taipei City and the Taipei metropolitan area, the capital of Taiwan and home to more than 7 million residents. Taipei Basin is in a major seismic hazard area and is prone to frequent large earthquakes producing strong ground motion. This unique three-dimension seismic array presents new frontiers for seismic research in Taiwan and, along with it, new challenges. Frequency-dependent and site-specific amplification of seismic waves from depth to surface has been observed: preliminary results indicate that the top few tens of meters of sediment--not the entire thickness--are responsible for significant frequency-dependent amplification; amplitudes of seismic waves at the surface may be as much as seven times that at depth. Dominant amplification frequencies are interpreted as quarter-wavelength constructive interference between the surface and major interfaces in the sediments. Using surface stations with known orientation as a reference, borehole seismometer orientations in these data--which are unknown, and some of which vary considerably from event to event--have been determined using several methods. After low-pass filtering the strong motion data, iteratively rotating the two horizontal components from an individual borehole station and cross-correlating them with that from a co-located surface station has proven to be very effective. In cases where the iterative cross-correlation method does not provide a good fit, rotating both surface and borehole stations to a common axis of maximum seismic energy provides an alternative approach. The orientation-offset of a borehole station relative to the surface station may be estimated by iteratively rotating the horizontal components of both and calculating the time-integral of the amplitude squared of each component; the difference in orientation between the maximum at the surface and at depth indicates the difference in orientation of the seismometers. After the horizontal orientations of borehole seismometers are correctly resolved, these data can be used in various scientific studies. Up-going and reflected down-going shear waves can be clearly identified, providing an excellent dataset for the study of interval velocity and seismic Q, localized shear wave splitting, and anisotropy. Further refinement of the geophysical structure of Taipei Basin and Northern Taiwan is also possible by combining data from the SMDA with that from the large array of surface stations maintained by the Central Weather Bureau.
Young, B.; Chen, K.; Chiu, J.
Frozen plasma motion in a strong magnetic field.
NASA Astrophysics Data System (ADS)
The authors propose a method for determining plasma flows in a strong magnetic field. An analytical solution is found for the plasma motion in an alternating dipole field. A regular plasma motion occurs in the fluctuating nonuniform magnetic field, even with no regular variations.
Gorbachev, V. S.; Kelner, S. R.
Length of a day and the strong Taiwan region earthquake of 26th December 2006
NASA Astrophysics Data System (ADS)
Coincidence of earthquakes with maximum amplitudes of the length of a day record since beginning of the year 2006 during the extreme Earth's rotation deceleration has proved that variations of the Earth's rotation triggered earthquakes in Taiwan-Luzon collision area of Eurasian and Philippine Sea plates. This area is characteristic by obduction of oceanic lithosphere over continent in Taiwan and the retreat of Manila subduction zone owing to gravity subsidence. The last but one of the coincidence series had been the strong Taiwan region earthquake of 26th December 2006. To verify the coincidence relationship for larger period, 59 samples of detailed seismic investigation of Kao et al. (2000) from 1964 to 1996 were used, further 11 samples of USGS Catalogue over 5.8 magnitude and schematically 900 earthquakes over 3 magnitude for period 1996-2006 covering the period from minimum to maximum Moon's declination. Final investigation has shown that westward collision events coincide with length of a day maxima, however the events along northward directed faults coincide with length of a day minima, i.e. the maximum Earth's rotation. This coincidence of westward and northward collision events is statistically significant and it supports that the driving mechanism of the Philippine Sea plate as a buffer plate is controlled by forces following from the Earth's rotation as tidal drag and E�tv�s force. The Philippine Sea plate is a product of tidal force which had broken the oceanic lithosphere on equator 35-60 Ma ago, today witnessed as fossil mid-ocean ridge in the middle of the plate. The young oceanic lithosphere 35 Ma ago could not subduct beneath the Eurasian continent and following obduction created the folded area of Taiwan.
Ostrihansky, Lubor
Phase derivatives and simulation of strong ground motions
Phase derivatives can be used to compute instantaneous frequency and envelope delay (also known as group delay). Envelope delay, in the guise of phase differences, has been used by engineers in the simulation of strong ground motion, particularly as a way of controlling the duration of motion. Simulations using the stochastic method, in which duration is a simple function of source duration and a path-dependent duration, possess envelope delay properties similar to those from simulations based on phase differences. Envelope delay provides a way of extending the standard stochastic method to produce nonstationary frequency content, as produced by ground motions containing surface waves.
Boore, D. M.
Optimum strong-motion array geometry for source inversion - II
Optimum strong-motion array geometry for source inversions is determined for each of three types of earthquake faults: strike-slip, dip-slip and offshore subduction thrust. It is found that the complete Green's function is capable of stabilizing the accuracy of an inversion solution obtained using theoretical seismograms, regardless of the differences in array configuration. The optimum strong-motion array for a strike-slip fault is characterized by stations well distributed in azimuth, while the optimum array for a dip-slip event has stations arranged in a grid-shaped form. -from Author
Iida, M.
A simple model for strong ground motions and response spectra
A simple model for the description of strong ground motions is introduced. The model shows that response spectra can be estimated by using only four parameters of the ground motion, the RMS acceleration, effective duration and two corner frequencies that characterize the effective frequency band of the motion. The model is windowed band-limited white noise, and is developed by studying the properties of two functions, cumulative squared acceleration in the time domain, and cumulative squared amplitude spectrum in the frequency domain. Applying the methods of random vibration theory, the model leads to a simple analytical expression for the response spectra. The accuracy of the model is checked by using the ground motion recordings from the aftershock sequences of two different earthquakes and simulated accelerograms. The results show that the model gives a satisfactory estimate of the response spectra.
Safak, Erdal; Mueller, Charles; Boatwright, John
Predicting Strong Ground Motion from Weak Ground Motion (Beno Gutenberg Medal Lecture)
NASA Astrophysics Data System (ADS)
Predicting strong ground motion from future earthquakes is among the most important research topics in seismology. Typically, seismologists do this through ground motion prediction equations that express relationships between earthquake characteristics and ground motion intensity. In some locations (e.g., Cascadia) there is relatively little data to constrain these relationships. For all areas there is the problem that there are few records of ground motion available close to large earthquakes. As a result, seismologists are increasingly turning to simulations to compensate for this lack of data, but validating the accuracy of these simulations is critically important. In this talk I present two new approaches for strong ground motion prediction. Both methods rely on data that is approximately one million times weaker in amplitude than the strong ground motion of interest. The first method uses the recently discovered phenomenon of tectonic tremor to constrain the amplitude decay with distance of seismic waves in subduction zones. The abundant data represented by tremor should allow us to explore the variability of ground motion with distance both regionally, and between different subduction zones. The second method uses the ambient seismic field to construct virtual earthquakes that predict spatial variations in long period strong ground motion for scenario earthquakes.
Beroza, Gregory
An Analytic Method for Strong Motion Studies in Layered Media.
National Technical Information Service (NTIS)
An analytic method is presented for calculating strong motion spectra and the response to arbitrary input in layered media. The method is based on the removal of secular terms at resonance of the equations with polynomial linearity. Through a convenient p...
A. Askar A. S. Cakmak H. Engin
Insight into Strong Motion Behavior of Large Concrete Structures
\\u000a The inability to induce strong motion excitation levels in structures is often cited as a limiting factor in evaluating the\\u000a seismic performance of large concrete dams. The advent of modern computational tools that provide advanced non-linear analysis\\u000a capabilities for these structures contributes to the view held by many analysts that low-level response monitoring does not\\u000a contribute meaningful insights to overall
Nick von Gersdorff; Zee Duron; Vincent Chiarito
Enhancement of the national strong-motion network in Turkey
Two arrays comprising 20 strong-motion sensors were established in western Turkey. The 14 stations of BYTNet follow a N-S trending line about 65 km in length, normal to strands of the North Anatolian fault that runs between the cities of Bursa and Yalova. Here the dominant character of the potential fault movement is a right-lateral transform slip. The DATNet array, comprising a total of eight stations, is arranged along a 110-km-long E-W trending direction along the Menderes River valley between Denizli and Aydin. (Two stations in this array were incorporated from the existing Turkish national strong-motion network.) This is an extensional tectonic environment, and the network mornitors potential large normal-faulting earthquakes on the faults in the valley. The installation of the arrays was supported by the North Atlantic Treaty Organization (NATO) under its Science for Peace Program. Maintenance and calibration is performed by the General Directorate of Disaster Affairs (GDDA) according to a protocol between Middle East Technical University (METU) and GDDA. Many young engineers and scientists have been trained in network operation and evaluation during the course of the project, and an international workshop dealing with strong-motion instrumentation has been organized as part of the project activities.
Gulkan, P.; Ceken, U.; Colakoglu, Z.; Ugras, T.; Kuru, T.; Apak, A.; Anderson, J. G.; Sucuoglu, H.; Celebi, M.; Akkar, D. S.; Yazgan, U.; Denizlioglu, A. Z.
Establishment of Antakya Basin Strong Ground Motion Monitoring System
NASA Astrophysics Data System (ADS)
Turkey is located in one of the most active earthquake zones of the world. The cities located along the North Anatolian Fault (NAF) and the East Anatolian Fault (EAF) are exposed to significant earthquake hazard. The Hatay province near the southern terminus of the EAF has always experienced a significant seismic activity, since it is on the intersection of the northernmost segment of Dead Sea Fault Zone coming from the south, with the Cyprean Arc approaching from south-west. Historical records extending over the last 2000 years indicate that Antakya, founded in the 3rd century B.C., is effected by intensity IX-X earthquakes every 150 years. In the region, the last destructive earthquake occurred in 1872. Destructive earthquakes should be expected in the region in the near future similar to the ones that occurred in the past. The strong response of sedimentary basins to seismic waves was largely responsible for the damage produced by the devastating earthquakes of 1985 Michoacan Earthquake which severely damaged parts of Mexico City, and the 1988 Spitak Earthquake which destroyed most of Leninakan, Armenia. Much of this devastating response was explained by the conversion of seismic body waves to surface waves at the sediment/rock contacts of sedimentary basins. "Antakya Basin Strong Ground Motion Monitoring System" is set up with the aim of monitoring the earthquake response of the Antakya Basin, contributing to our understanding of basin response, contributing to earthquake risk assessment of Antakya, monitoring of regional earthquakes and determining the effects of local and regional earthquakes on the urban environment of Antakya. The soil properties beneath the strong motion stations (S-Wave velocity structure and dominant soil frequency) are determined by array measurements that involve broad-band seismometers. The strong motion monitoring system consists of six instruments installed in small buildings. The stations form a straight line along the short axis of Antakya basin passing through the city center. They are equipped with acceleration sensors, GPS and communication units and operate in continuous recording mode. For on-line data transmission the EDGE mode of available GSM systems are employed. In the array measurements for the determination of soil properties beneath the stations two 4-seismometer sets have been utilized. The system is the first monitoring installment in Turkey dedicated to understanding basin effects. The records obtained will allow for the visualization of the propagation of long-period ground motion in the basin and show the refraction of surface waves at the basin edge. The records will also serve to enhance our capacity to realistically synthesize the strong ground motion in basin-type environments.
Durukal, E.; �zel, O.; Bikce, M.; Gene?, M. C.; Kac?n, S.; Erdik, M.; Safak, E.; �ver, S.
Explosion source strong ground motions in the Mississippi embayment
Two strong-motion arrays were deployed for the October 2002 Embayment Seismic Excitation Experiment to study the spatial variation of strong ground motions in the deep, unconsolidated sediments of the Mississippi embayment because there are no comparable strong-motion data from natural earthquakes in the area. Each linear array consisted of eight three-component K2 accelerographs spaced 15 m apart situated 1.2 and 2.5 kin from 2268-kg and 1134-kg borehole explosion sources, respectively. The array data show distinct body-wave and surface-wave arrivals that propagate within the thick, unconsolidated sedimentary column, the high-velocity basement rocks, and small-scale structure near the surface. Time-domain coherence of body-wave and surface-wave arrivals is computed for acceleration, velocity, and displacement time windows. Coherence is high for relatively low-frequency verticalcomponent Rayleigh waves and high-frequency P waves propagating across the array. Prominent high-frequency PS conversions seen on radial components, a proxy for the direct S wave from earthquake sources, lose coherence quickly over the 105-m length of the array. Transverse component signals are least coherent for any ground motion and appear to be highly scattered. Horizontal phase velocity is computed by using the ratio of particle velocity to estimates of the strain based on a plane-wave-propagation model. The resulting time-dependent phase-velocity map is a useful way to infer the propagation mechanisms of individual seismic phases and time windows of three-component waveforms. Displacement gradient analysis is a complementary technique for processing general spatial-array data to obtain horizontal slowness information.
Langston, C. A.; Bodin, P.; Powell, C.; Withers, M.; Horton, S.; Mooney, W.
Vertical crustal motion of active plate convergence in Taiwan derived from tide gauge, altimetry, and GPS data
NASA Astrophysics Data System (ADS)
Located at the converging junction between the Eurasian and Philippine Sea plates, the island of Taiwan is subject to an active lithospheric deformation as well as seismicity. Taking the difference between the satellite altimetry data (ALT) that give the absolute sea level variation and the tide gauge data (TG) that record the relative sea level variation, we obtain the absolute vertical crustal motion of the tide gauge sites. We use 20 TG stations along the west and east coasts of Taiwan along with the ALT measurements from the TOPEX/Poseidon-Jason satellites in the nearby waters. The ALT-TG results are compared with vertical GPS measurements in discussing vertical motion. We find a general subsidence of the entire Taiwan coast during the past two decades. The west coast sees no prominent vertical motion but with a severe local subsidence due to the over-withdrawal of groundwater. On the east coast, the ALT-TG results in the northern section demonstrate a northward dipping motion. The elastic thickness of the neighboring oceanic lithosphere modeled as an elastic plate with the flexure of the subducting plate shows that the adjacent Philippine Sea plate should be an old, thick oceanic plate, which could drag the slab into the mantle as manifested in a gentle northward subsidence in the northeast Taiwan. In the southern section of the east coast, the ALT-TG results reveal a segmented or undulating pattern in the vertical-motion rates. Judging from the different behaviors between the co-seismic and interseismic vertical motions marked by the major earthquakes during the studied period, we postulate a temporal saw-tooth scenario for the deformation in phases. It demonstrates the opposite motions under different mechanisms in the frontal sections of the subduction zone, which can be understood with lateral collision and slab dragging subject to varied temporal and spatial dependences.
Chang, Emmy T. Y.; Chao, Benjamin F.; Chiang, Chieh-Chung; Hwang, Cheinway
Can mobile phones used in strong motion seismology?
NASA Astrophysics Data System (ADS)
Micro Electro-Mechanical Systems (MEMS) accelerometers are electromechanical devices able to measure static or dynamic accelerations. In the 1990s MEMS accelerometers revolutionized the automotive-airbag system industry and are currently widely used in laptops, game controllers and mobile phones. Nowadays MEMS accelerometers seems provide adequate sensitivity, noise level and dynamic range to be applicable to earthquake strong motion acquisition. The current use of 3 axes MEMS accelerometers in mobile phone maybe provide a new means to easy increase the number of observations when a strong earthquake occurs. However, before utilize the signals recorded by a mobile phone equipped with a 3 axes MEMS accelerometer for any scientific porpoise, it is fundamental to verify that the signal collected provide reliable records of ground motion. For this reason we have investigated the suitability of the iPhone 5 mobile phone (one of the most popular mobile phone in the world) for strong motion acquisition. It is provided by several MEMS devise like a three-axis gyroscope, a three-axis electronic compass and a the LIS331DLH three-axis accelerometer. The LIS331DLH sensor is a low-cost high performance three axes linear accelerometer, with 16 bit digital output, produced by STMicroelectronics Inc. We have tested the LIS331DLH MEMS accelerometer using a vibrating table and the EpiSensor FBA ES-T as reference sensor. In our experiments the reference sensor was rigidly co-mounted with the LIS331DHL MEMS sensor on the vibrating table. We assessment the MEMS accelerometer in the frequency range 0.2-20 Hz, typical range of interesting in strong motion seismology and earthquake engineering. We generate both constant and damped sine waves with central frequency starting from 0.2 Hz until 20 Hz with step of 0.2 Hz. For each frequency analyzed we generate sine waves with mean amplitude 50, 100, 200, 400, 800 and 1600 mg0. For damped sine waves we generate waveforms with initial amplitude of 2 g0. Our tests show as, in the frequency and amplitude range analyzed (0.2-20 Hz, 10-2000 mg0), the LIS331DLH MEMS accelerometer have excellent frequency and phase response, comparable with that of some standard FBA accelerometer used in strong motion seismology. However, we found that the signal recorded by the LIS331DLH MEMS accelerometer slightly underestimates the real acceleration (of about 2.5%). This suggests that may be important to calibrate a MEMS sensor before using it in scientific applications. A drawback of the LIS331DLH MEMS accelerometer is its low sensitivity. This is an important limitation of all the low cost MEMS accelerometers; therefore nowadays they are desirable to use only in strong motion seismology. However, the rapid development of this technology will lead in the coming years to the development of high sensitivity and low noise digital MEMS sensors that may be replace the current seismic accelerometer used in seismology. Actually, the real main advantage of these sensors is their common use in the mobile phones.
D'Alessandro, Antonino; D'Anna, Giuseppe
Strong motions in Alaska-type subduction zone environments
Peak accelerations of Alaska-Aleutian strong motion records are compared with those collected mostly in the western US. The most prominent difference is the larger scatter of Alaskan peak accelerations. The high scatter is attributed primarily to high variability of stress drops typical for some subduction zones. For critical engineering projects that must satisfy high probabilities of non-exceedence it implies that in Alaskan-type environments higher design peak accelerations may have to be adopted than under comparable cricumstances in the western US.
Jacob, K.H.; Mori, J.
Future of the US National Strong-Motion Program
These reports are presented in response to a charge of the Earthquake Hazards Reduction Program (EHRP) Program Council of the U.S. Geological Survey to 'define the future of the USGS National Strong-Motion Program (NSMP)' (Appendix A). The council requested that a 'Vision Paper' and an 'Options Document' be prepared. Each of these reports is a separate document. The 'Executive Summary' of both reports is presented here under separate cover. The content of the reports and the executive summary is organized to the extent possible according to the main charges of the EHRP Program Council. Detailed evaluation of charges and questions posed by the Council with the benefit of modern GIS tools and the recent deliberations of three national workshops have yielded substantial new insight regarding the status of strong-motion measurement in the US. These reports are intended as an objective evaluation of the nation's need and capability to record the next major earthquake at locations of most significance for public safety.
Committee for the Future of the US National Strong-Motion Program
Database for earthquake strong motion studies in Italy
We describe an Italian database of strong ground motion recordings and databanks delineating conditions at the instrument sites and characteristics of the seismic sources. The strong motion database consists of 247 corrected recordings from 89 earthquakes and 101 recording stations. Uncorrected recordings were drawn from public web sites and processed on a record-by-record basis using a procedure utilized in the Next-Generation Attenuation (NGA) project to remove instrument resonances, minimize noise effects through low- and high-pass filtering, and baseline correction. The number of available uncorrected recordings was reduced by 52% (mostly because of s-triggers) to arrive at the 247 recordings in the database. The site databank includes for every recording site the surface geology, a measurement or estimate of average shear wave velocity in the upper 30 m (Vs30), and information on instrument housing. Of the 89 sites, 39 have on-site velocity measurements (17 of which were performed as part of this study using SASW techniques). For remaining sites, we estimate Vs30 based on measurements on similar geologic conditions where available. Where no local velocity measurements are available, correlations with surface geology are used. Source parameters are drawn from databanks maintained (and recently updated) by Istituto Nazionale di Geofisica e Vulcanologia and include hypocenter location and magnitude for small events (M< ??? 5.5) and finite source parameters for larger events. ?? 2009 A.S. Elnashai & N.N. Ambraseys.
Scasserra, G.; Stewart, J. P.; Kayen, R. E.; Lanzo, G.
High-frequency filtering of strong-motion records
The influence of noise in strong-motion records is most problematic at low and high frequencies where the signal to noise ratio is commonly low compared to that in the mid-spectrum. The impact of low-frequency noise (5 Hz) on computed pseudo-absolute response spectral accelerations (PSAs). In contrast to the case of low-frequency noise our analysis shows that filtering to remove high-frequency noise is only necessary in certain situations and that PSAs can often be used up to 100 Hz even if much lower high-cut corner frequencies are required to remove the noise. This apparent contradiction can be explained by the fact that PSAs are often controlled by ground accelerations associated with much lower frequencies than the natural frequency of the oscillator because path and site attenuation (often modelled by Q and ?, respectively) have removed the highest frequencies. We demonstrate that if high-cut filters are to be used, then their corner frequencies should be selected on an individual basis, as has been done in a few recent studies.
Douglas, J.; Boore, D. M.
Dynamic rupture scenarios for strong ground motion prediction
NASA Astrophysics Data System (ADS)
Spontaneous rupture models provide physically reasonable rupture processes under presumed fault geometry and stress field. We propose that dynamic rupture models based on geological or geomorphological data are used as earthquake scenarios for strong ground motion prediction. We apply our method to possible sources of earthquake occurring on the Uemachi fault systems. The Uemachi fault system runs just underneath the western part of Osaka plain, extends about 45 km, and dips 60 degrees to the east. We model the fault geometry from the surface traces and the shape of the Osaka basin-floor. The stress condition is presumed based on slip distributions on the fault. Spatially varied cumulative slip distribution along the strike of the Uemachi fault system was obtained by reflection surveys, borehole data, etc. The borehole data at a site along the fault showed that the vertical slip on the earth's surface due to the last event was between 1.6 to 2.4 m (Sugiyama et al., 2003). Combining these data, we presume an prototype of the slip distribution along strike. The slip distribution along dip is modeled through simulations of spontaneous ruptures under vertically depth-dependent stress conditions to realize spontaneously stopping rupture near the bottom of the seismogeneic zone. Onto this large-scale heterogeneous slip distribution model, we add fractal heterogeneities in small-scale created from different random numbers. These slip distributions are converted to the distributions of static stress drop. For each stress drop model, some hypocenter locations are assumed. We calculate dynamic rupture processes by the finite-difference method (Kase, 2010), assuming the slip-weakening friction law. Rupture area and rupture time on each point depend on stress model and hypocenter location. Based on these rupture scenarios, we simulate lower frequency components of ground motion by the finite-difference method (Pitarka, 1999) excluding the shallow sediment above the engineering basement. Higher frequency components are computed by the stochastic Green's function method (Onishi and Horike, 2000). Effects of the shallow alluvium layers are calculated by 1D multi-reflection theory considering nonlinear effect by equivalent linear technique using a computer code DYNEQ (Yoshida and Suetomi, 1996).
Kase, Y.; Sekiguchi, H.
Lotung large-scale seismic test strong motion records
The Electric Power Research Institute (EPRI), in cooperation with the Taiwan Power Company (TPC), constructed two models (1/4 scale and 1/12 scale) of a nuclear plant concrete containment structure at a seismically active site in Lotung, Taiwan. Extensive instrumentation was deployed to record both structural and ground responses during earthquakes. The experiment, generally referred to as the Lotung Large-Scale Seismic Test (LSST), was used to gather data for soil-structure interaction (SSI) analysis method evaluation and validation as well as for site ground response investigation. A number of earthquakes having local magnitudes ranging from 4.5 to 7.0 have been recorded at the LSST site since the completion of the test facility in September 1985. This report documents the earthquake data, both raw and processed, collected from the LSST experiment. Volume 1 of the report provides general information on site location, instrument types and layout, data acquisition and processing, and data file organization. The recorded data are described chronologically in subsequent volumes of the report.
Not Available
Perceptual Training Strongly Improves Visual Motion Perception in Schizophrenia
ERIC Educational Resources Information Center
Schizophrenia patients exhibit perceptual and cognitive deficits, including in visual motion processing. Given that cognitive systems depend upon perceptual inputs, improving patients' perceptual abilities may be an effective means of cognitive intervention. In healthy people, motion perception can be enhanced through perceptual learning, but it�
Norton, Daniel J.; McBain, Ryan K.; Ongur, Dost; Chen, Yue
Effect of tilt on strong motion data processing
In the near-field of an earthquake the effects of the rotational components of ground motion may not be negligible compared to the effects of translational motions. Analyses of the equations of motion of horizontal and vertical pendulums show that horizontal sensors are sensitive not only to translational motion but also to tilts. Ignoring this tilt sensitivity may produce unreliable results, especially in calculations of permanent displacements and long-period calculations. In contrast to horizontal sensors, vertical sensors do not have these limitations, since they are less sensitive to tilts. In general, only six-component systems measuring rotations and accelerations, or three-component systems similar to systems used in inertial navigation assuring purely translational motion of accelerometers can be used to calculate residual displacements. ?? 2004 Elsevier Ltd. All rights reserved.
Graizer, V. M.
Typhoon-induced strong surface flows in the Taiwan strait and pacific
Surface Velocity Program drifters drogued at 15 m depth were deployed in the Taiwan Strait (TS) and Luzon Strait in 2005 and\\u000a 2006. Several drifters in the TS and the Pacific were fortuitously overrun by the typhoon Hai-Tang (July 2005) and Shan-Shan\\u000a (September 2006), respectively. The drifter and QuikSCAT wind data clearly demonstrate that the surface current over the TS
Yu-Chia Chang; Ruo-Shan Tseng; Luca R. Centurioni
Detection of soil liquefaction from strong motion records
SUMMARY During the recent earthquakes in Japan and the U.S.A. a number of records from liqueed-soil sites have been obtained. The ground motion parameters from these sites were studied and several methods for detection of liquefaction from seismic records were developed. The methods, however, focus mainly on the horizontal ground motion and may interpret as liquefaction-induced some records from soft-soil
Mladen V. Kostadinov; Fumio Yamazaki
Strong ground motions generated by earthquakes on creeping faults
NASA Astrophysics Data System (ADS)
tenet of earthquake science is that faults are locked in position until they abruptly slip during the sudden strain-relieving events that are earthquakes. Whereas it is expected that locked faults when they finally do slip will produce noticeable ground shaking, what is uncertain is how the ground shakes during earthquakes on creeping faults. Creeping faults are rare throughout much of the Earth's continental crust, but there is a group of them in the San Andreas fault system. Here we evaluate the strongest ground motions from the largest well-recorded earthquakes on creeping faults. We find that the peak ground motions generated by the creeping fault earthquakes are similar to the peak ground motions generated by earthquakes on locked faults. Our findings imply that buildings near creeping faults need to be designed to withstand the same level of shaking as those constructed near locked faults.
Harris, Ruth A.; Abrahamson, Norman A.
Strong ground motions generated by earthquakes on creeping faults
A tenet of earthquake science is that faults are locked in position until they abruptly slip during the sudden strain-relieving events that are earthquakes. Whereas it is expected that locked faults when they finally do slip will produce noticeable ground shaking, what is uncertain is how the ground shakes during earthquakes on creeping faults. Creeping faults are rare throughout much of the Earth's continental crust, but there is a group of them in the San Andreas fault system. Here we evaluate the strongest ground motions from the largest well-recorded earthquakes on creeping faults. We find that the peak ground motions generated by the creeping fault earthquakes are similar to the peak ground motions generated by earthquakes on locked faults. Our findings imply that buildings near creeping faults need to be designed to withstand the same level of shaking as those constructed near locked faults.
Harris, Ruth A.; Abrahamson, Norman A.
Domain wall motion induced by strong microwave fields
A new high power effect in ferrites, the motion of domain walls induced by microwave pulses is described. In high power phase shifters using ferrite toroids this effect can change the remanent magnetization and hence change the insertion phase of the device. A theoretical explanation of these effects is obtained by considering a partially magnetized ferrite material having uniaxial anisotropy
E. Schlomann; J. Dawson Milnet
Validation of Predicted Strong Ground Motion Based on Energy Index of Seismic Wave
NASA Astrophysics Data System (ADS)
A model fault is supposed and strong ground motions are predicted around the fault by stochastic Green's function method to compare indexes such as PGA, PGV and energy index named IED(Incident Energy Density). It is necessary to show the validity of the predicted motions but the indexes such as PGA and PGV should not be enough to represent the characteristics of earthquake ground motions. In this study, we study the applicability of IED of a seismic wave to estimate validity of the predicted strong ground motion. IED of a predicted strong ground motion has good relation to magnitude of earthquake. The variation of IED due to the phase characteristics of element seismic waves used in stochastic Green's function method or the difference of soil characteristics is less than PGA and PGV. It can be concluded that if IED is added to evaluation indexes, it is possible to estimate more rationally the validity of a predicted strong ground motion.
Hirai, Toshiyuki; Sawada, Sumio
Strong-field ionization of diatomic molecules and companion atoms: Strong-field approximation and tunneling theory including nuclear motion
We present a detailed comparison of strong-field ionization of diatomic molecules and their companion atoms with nearly equal ionization potentials. We perform calculations in the length and velocity gauge formulations of the molecular strong-field approximation and with the molecular tunneling theory, and in both cases we consider effects of nuclear motion. A comparison of our results with experimental data shows that the length gauge strong-field approximation gives the most reliable predictions.
Kjeldsen, Thomas Kim; Madsen, Lars Bojer [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C (Denmark)
Strong Ground-Motion Prediction from Stochastic-Dynamic Source Models
In the absence of sufficient data in the very near source, predictions of the intensity and variability of ground motions from future large earthquakes depend strongly on our ability to develop realistic models of the earthquake source. In this article we simulate near-fault strong ground motion using dynamic source models. We use a boundary integral method to simulate dynamic rupture
Mariagiovanna Guatteri; P. Martin Mai; Gregory C. Beroza; John Boatwright
Nonlinear Motion of Plasmas in a Strong Electromagnetic Field.
National Technical Information Service (NTIS)
A plasma subjected to a strong electromagnetic field with a finite wavelength is considered and a method of obtaining the nonlinear plasma current in all orders of this field presented; both electrostatic and electromagnetic perturbations are considered. ...
N. Thehung
Site Characterization of Italian Strong Motion Recording Stations
NASA Astrophysics Data System (ADS)
A dataset of site conditions at 101 Italian ground motion stations with recorded motions has been compiled that includes geologic characteristics and seismic velocities. Geologic characterization is derived principally from local geologic investigations by ENEL that include detailed mapping and cross sections. For sites lacking such detailed geologic characterization, the geology maps of the by Servizio Geologico d'Italia are used. Seismic velocities are extracted from the literature and the files of consulting engineers, geologists and public agencies for 33 sites. Data sources utilized include post earthquake site investigations (Friuli and Irpinia events), microzonation studies, and miscellaneous investigations performed by researchers or consulting engineers/geologists. Additional seismic velocities are measured by the authors using the controlled source spectral analysis of surface waves (SASW) method for 18 sites that recorded the 1997-1998 Umbria Marche earthquake sequence. The compiled velocity measurements provide data for 51 of the 101 sites. For the remaining sites, the average seismic velocity in the upper 30 m (Vs30) is estimated using a hybrid approach. For young Quaternary alluvium, Vs30 an existing empirical relationship for California sites by Wills and Clahan (2006) is used, which we justify by validating this relationship against Italian data. For Tertiary Limestone and Italian Mesozoic rocks, empirical estimates of Vs30 are developed using the available data. This work is also presented in Scasserra et al. (2008: JEE, in review).
Scasserra, Giuseppe; Stewart, Jonathan P.; Kayen, Robert E.; Lanzo, Giuseppe
SISMA (Site of Italian Strong Motion Accelerograms): a Web-Database of Ground Motion Recordings for Engineering Applications
The paper describes a new website called SISMA, i.e. Site of Italian Strong Motion Accelerograms, which is an Internet portal intended to provide natural records for use in engineering applications for dynamic analyses of structural and geotechnical systems. SISMA contains 247 three-component corrected motions recorded at 101 stations from 89 earthquakes that occurred in Italy in the period 1972-2002. The database of strong motion accelerograms was developed in the framework of a joint project between Sapienza University of Rome and University of California at Los Angeles (USA) and is described elsewhere. Acceleration histories and pseudo-acceleration response spectra (5% damping) are available for download from the website. Recordings can be located using simple search parameters related to seismic source and the recording station (e.g., magnitude, V{sub s30}, etc) as well as ground motion characteristics (e.g. peak ground acceleration, peak ground velocity, peak ground displacement, Arias intensity, etc.)
Scasserra, Giuseppe; Lanzo, Giuseppe; D'Elia, Beniamino [Dipartimento di Ingegneria Strutturale e Geotecnica, Sapienza Universita di Roma, Via A. Gramsci 53, 00197, Rome (Italy); Stewart, Jonathan P. [Civil and Environmental Engineering Department, University of California, Los Angeles, 5371 Boelter Hall, Los Angeles, CA 90095 (United States)
Strong ground motion simulation of the 2003 Bam, Iran, earthquake using the empirical Green's function method
NASA Astrophysics Data System (ADS)
The 2003 Bam, Iran, earthquake caused catastrophic damage to the city of Bam and neighboring villages. Given its magnitude ( M w ) of 6.5, the damage was remarkably large. Large-amplitude ground motions were recorded at the Bam accelerograph station in the center of Bam city by the Building and Housing Research Center (BHRC) of Iran. We simulated the Bam earthquake acceleration records at three BHRC strong-motion stations�Bam, Abaraq, and Mohammad-Abad�by the empirical Green's function method. Three aftershocks were used as empirical Green's functions. The frequency range of the empirical Green's function simulations was 0.5-10 Hz. The size of the strong motion generation area of the mainshock was estimated to be 11 km in length by 7 km in width. To estimate the parameters of the strong motion generation area, we used 1D and 2D velocity structures across the fault and a combined source model. The empirical Green's function method using a combination of aftershocks produced a source model that reproduced ground motions with the best fit to the observed waveforms. This may be attributed to the existence of two distinct rupture mechanisms in the strong motion generation area. We found that the rupture starting point for which the simulated waveforms best fit the observed ones was near the center of the strong motion generation area, which reproduced near-source ground motions in a broadband frequency range. The estimated strong motion generation area could explain the observed damaging ground motion at the Bam station. This suggests that estimating the source characteristics of the Bam earthquake is very important in understanding the causes of the earthquake damage.
Sadeghi, Hossein; Miyake, Hiroe; Riahi, Ali
Strong motion: an extended NCQ model for non linear wave propagation simulations
In this work, we consider an extended viscoelastic NCQ model to simulate seismic wave propagation in alluvial basins in the case of strong motions. This constitutive model involves both non linear elasticity and non linear viscous behaviour. The main objective of this model is to reproduce the dependence of the shear modulus and damping on the motion amplitude. To do
J. Semblat; N. Del�pine; L. Lenti; G. Bonnet
Implications of the Northridge earthquake for strong ground motions from thrust faults
The peak accelerations recorded on alluvial sites during the Northridge earthquake were about 50% larger than the median value predicted by current empirical attenuation relations at distances less than about 30 km. This raises the question of whether the ground motions from the Northridge earthquake are anomalous for thrust events or are representative of ground motions expected in future thrust earthquakes. Since the empirical data base contains few strong-motion records close to large-thrust earthquakes, it is difficult to assess whether the Northridge ground motions are anomalous based on recorded data alone. For this reason, we have used a broadband strong-motion simulation procedure to help assess whether the ground motions were anomalous. The simulation procedure has been validated against a large body of strong-motion data from California earthquakes, and so we expect it to produce accurate estimates of ground motions for any given rupture scenario, including blind-thrust events for which no good precedent existed in the strong-motion data base until the occurrence of the Northridge earthquake. The ground motions from the Northridge earthquake and our simulations of these ground motions have a similar pattern of departure from empirical attenuation relations for thrust earthquakes: the peak accelerations are at about the 84th percentile level for distances within 20 to 30 km and follow the median level for larger distances. This same pattern of departure from empirical attenuation relations was obtained in our simulations of the peak accelerations of an Elysian Park blind-thrust event prior to the occurrence of the Northridge earthquake. Since we are able to model this pattern with broadband simulations, and had done so before the Northridge earthquake occurred, this suggests that the Northridge strong-motion records are not anomalous and are representative of ground motions close to thrust faults. Accordingly, it seems appropriate to include these recordings in strong-motion data sets that are used to develop empirical ground-motion attenuation relations for thrust faults and to use this augmented data set as the basis for evaluating the need for modifications in design coefficients in the seismic provisions of building codes.
Somerville, P.; Saikia, C.; Wald, D.; Graves, R.
Generation of Strong Motion Pulses during the 2011 Tohoku Earthquake and Their Modeling
NASA Astrophysics Data System (ADS)
The 2011 Tohoku, Japan, earthquake is obviously the first M9 earthquake which was recorded by dense strong motion networks such as K-NET, etc. From engineering point of view, the most striking feature of strong ground motions of the earthquake is the generation of pulses. Strong ground motions in the frequency range from 0.2 to 1 Hz observed at many sites along the coast of Miyagi through Ibaraki Prefecture during the Tohoku earthquake are characterized by distinctive pulses. It is significantly important to consider the generation of such pulses in the strong-motion prediction for mega earthquakes, especially when the prediction is aimed at seismic design of structures. To model strong motion pulses from the Tohoku earthquake, a source model with rectangular subevents was newly developed for the earthquake. The locations of the subevents were determined from the arrival times. The sizes of the subevents were determined so that the width of the pulses can be reproduced appropriately. The constructed source model involves 9 subevents with relatively small size (on the order of several kilometers), located off-the-coast of Miyagi through off-the-coast of Ibaraki. The strong ground motions from the source model were calculated based on site amplification and phase characteristics (Nozu et al., 2006). The agreement between the observed and calculated ground motions was quite satisfactory, especially for velocity waveforms (0.2-1.0 Hz) including near-source pulses. Strong ground motions from the same earthquake have been modeled using a source model with SMGAs with a size of tens of kilometers (e.g., Kurahashi and Irikura, 2011; Satoh, 2011; Asano and Iwata, 2011; Kawabe et al., 2011). However, the relatively small width of the observed pulses requires smaller subevents. The small subevents used in the present study is, in essence, equivalent to the "super asperities" proposed by Matsushima and Kawase (2006) to explain strong motion pulses from the 1978 Miyagi-ken oki earthquake (Mw7.6). The author redefines the subevents as SPGAs (Strong-motion Pulse Generation Areas), because the definition of "asperity" itself is currently somewhat ambiguous. The observed strong motion pulses require a very high moment rate within a small area. The future work should be aimed at revealing the dynamics of SPGAs. The SPGA model for the 2011 Tohoku earthquake
Nozu, A.
Estimation of strong ground motions from hypothetical earthquakes on the Cascadia subduction zone, Pacific Northwest
Strong ground motions are estimated for the Pacific Northwest assuming that large shallow earthquakes, similar to those experienced in southern Chile, southwestern Japan, and Colombia, may also occur on the Cascadia subduction zone. Fifty-six strong motion recordings for twenty-five subduction earthquakes of Ms???7.0 are used to estimate the response spectra that may result from earthquakes Mw<81/4. Large variations in observed ground motion levels are noted for a given site distance and earthquake magnitude. When compared with motions that have been observed in the western United States, large subduction zone earthquakes produce relatively large ground motions at surprisingly large distances. An earthquake similar to the 22 May 1960 Chilean earthquake (Mw 9.5) is the largest event that is considered to be plausible for the Cascadia subduction zone. This event has a moment which is two orders of magnitude larger than the largest earthquake for which we have strong motion records. The empirical Green's function technique is used to synthesize strong ground motions for such giant earthquakes. Observed teleseismic P-waveforms from giant earthquakes are also modeled using the empirical Green's function technique in order to constrain model parameters. The teleseismic modeling in the period range of 1.0 to 50 sec strongly suggests that fewer Green's functions should be randomly summed than is required to match the long-period moments of giant earthquakes. It appears that a large portion of the moment associated with giant earthquakes occurs at very long periods that are outside the frequency band of interest for strong ground motions. Nevertheless, the occurrence of a giant earthquake in the Pacific Northwest may produce quite strong shaking over a very large region. ?? 1989 Birkha??user Verlag.
Heaton, T. H.; Hartzell, S. H.
Strong Ground Motion. Proceedings of the National Science Foundation Seminar Workshop Held at Rancho Santa Fe, California on February, 1978.
National Technical Information Service (NTIS)
Proceedings of a seminar-workshop dealing with mutual concerns of seismologists and engineers in strong ground motion are summarized. Discussions focused on three major areas: (1) characterization and parameterization of strong ground motion; (2) simulati...
On unstable ship motions resulting from strong non-linear coupling
In this paper, the modelling of strong parametric resonance in head seas is investigated. Non-linear equations of ship motions in waves describing the couplings between heave, roll and pitch are contemplated. A third-order mathematical model is introduced, aimed at describing strong parametric excitation associated with cyclic changes of the ship restoring characteristics. A derivative model is employed to describe the
Marcelo A. S. Neves; Claudio A. Rodr�guez
Estimation of Broadband Ground Motion at Ocean-bottom Strong-motion Stations for the 2003 Tokachi-oki Earthquake
NASA Astrophysics Data System (ADS)
The 2003 Tokachi-oki earthquake (MJMA8.0) occurred on September 25, 2003 (UT). In this study, we reproduce the broadband ground motion from the earthquake using near-field strong-motion records (accelerograms) at three ocean-bottom stations (KOB1, KOB2 and KOB3) on the sea floor off Kushiro, Hokkaido, installed by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). The distance and direction from the epicenter to KOB1, KOB2 and KOB3 are 28 km, east-southeast and 83 km,east and 80 km, east-northeast, respectively. Three components (x, y, z) strong motion observation system, enclosed within a cylindrical pressure housing, can record ground motion in broadband frequency range up to DC. The x component is parallel to the axis of the cylinder which is almost horizontal. Since it is suspected that the strong-motion observation systems themselves had moved during the main shock, a simple time-integration of the original acceleration results in wrong velocity and displacement ground motion. So we apply the following processing to the data: We assume that the motion of each strong-motion seismometer can be represented by (1) rotation around the cylinder axis (i.e., roll), (2) tilting of the cylinder (i.e., pitch), and (3) parallel motion. To estimate rotation and tilting, we first use a median-filter for the original records. After the compensation of these movements, the rotated records are integrated into velocity ones. Next, we follow the base-line correction method of Boore (2001) and obtain the ground motion using the amount of submarine upheaval estimated from the two seabed tsunami sensors near KOB1 and KOB3 by Hirata and Baba (2004). By this approach we have successfully obtained broadband velocity and displacement ground motion including DC components. The maximum horizontal (vector resultant) and vertical velocities at KOB1 and KOB3 are estimated to be approximately 160 cm/s, 40 cm/s and 130 cm/s, 20 cm/s, while the corresponding maximum accelerations are approximately 790 cm/s2, 130 cm/s2 at KOB1 and 880 cm/s2, 120 cm/s2 at KOB3, respectively. As for KOB2, since there is no seabed tsunami sensor near it, we assume from consideration of plausible fault models of the main shock that the vertical static displacement is nearly zero, and estimate the maximum horizontal and vertical velocities to be approximately 70 cm/s and 20 cm/s. The corresponding maximum horizontal and vertical accelerations are then approximately 590 cm/s2, 70 cm/s2, respectively. In this presentation, we will show particle velocity, and displacement at the three stations. We used the strong-motion data of JAMSTEC, which is opened through its homepage. (http://www.jamstec.go.jp)
Yamamoto, Y.; Takenaka, H.; Hirata, K.; Watanabe, T.
Amplification Characteristics during the Strong and Weak Ground Motions at the IWTH25 Station, Northeast Japan
NASA Astrophysics Data System (ADS)
Ground response is affected by the strength of input seismic ground motions. As the shear strain grows, the relationship between shear stress and shear strain becomes non-linear, which results in decrease of the rigidity and increase of the wave attenuation as shown in laboratory soil tests (e.g., Imazu and Fukutake,1986). According to previous studies about non-linear ground response using strong motion data, non-linear response is observed as a shift on the dominant frequency to lower frequency and decrease of amplification in horizontal motions. On the other hand, such distinct features of non-linearity are not observed in vertical motions which consist mainly of P-wave. The purpose of this study is to investigate the amplification characteristics due to strong and weak seismic ground motions. We analyzed the spectral amplitude ratios between the seismic motions recorded by surface and downhole sensors of a KiK-net station, IWTH25 (West Ichinoseki), in northeast Japan. This station is located above the source fault of the 2008 Iwate-Miyagi inland earthquake (mainshock) with Mw6.9 and recorded maximum vertical surface acceleration of nearly four times of gravity. We used strong ground motion data of the mainshock (PGA~4000gal at the surface) and weak ground motion data of the events before and after the mainshock (PGA~1-400gal). With those data we calculated surface-to-downhole spectral ratios in horizontal and vertical components of the direct P- and S-wave parts and compared them. For the spectral ratios in horizontal component of S-wave part we observed large differences between strong and weak motions. The spectral ratio of strong motion showed smaller amplitude at frequencies higher than 1Hz compared with the weak motions and did not show dominant peak. On the contrary, few differences were observed between the spectral ratios of strong and weak motions in vertical component of S-wave part. The spectral ratios in vertical component were different from those in horizontal component, whereas the spectral ratios of P- and S-wave parts were similar to each other for the same component. Considering the fact that incidence near the surface with low velocities is almost vertical, it implies that horizontal and vertical motions contain mainly S- and P-wave, respectively. The spectral ratios before and after the mainshock showed some differences near 10Hz in horizontal component and also small differences in vertical component. This may suggest that properties of surface layers change due to the strong motion. In order to see change in the properties of superficial layers during weak and strong motions, we model them down to downhole depth using theoretical transfer function and the observed spectral ratios. Acknowledgements: We used strong motion records of KiK-net operated by NIED.
Kimura, M.; Asano, K.; Iwata, T.
A study of the strong ground motion of the western Hidaka, Hokkaido earthquake
NASA Astrophysics Data System (ADS)
An attempt is made to model strong ground motion from the western Hidaka earthquake of January 23, 1981. First, the source parameters for this event are obtained from a study of teleseismic P and S waves. Parameter values are: focal depth = 110 km, fault strike = 248, dip angle = 80, rake angle = 97, source process time = 3-4 sec, and seismic moment = 2.2 x 10 to the 26th power dyne-cm. Then synthetic strong-motion seismograms are calculated for the source parameters obtained and the assumed plane-layered earth model. These seismograms are compared with the observed JMA strong-motion seismograms at seven stations in Hokkaido. The duration and amplitude behavior of observed strong-motion can be explained by the simple source and earth models, except data from Tomakomai, Urakawa and Obihiro whose observed seismograms show waves with abnormally large amplitude after the direct S wave arrival. These abnormal strong-motions may be due to propagational effects introduced by local crustal structure.
Sasatani, T.
A sequence of destructive earthquakes struck mid-Niigata prefecture in central Japan during late October 2004. This paper examines some of the characteristics of the strong ground motions recorded during the main shock and aftershocks of the earthquakes, and the effects of these records on the linear and nonlinear dynamic response of single-degree-of-freedom systems. The studies suggest that a ground motion
Junichi SAKAI; Stephen A. MAHIN
A strong-motion database from the Peru�Chile subduction zone
Earthquake hazard along the Peru�Chile subduction zone is amongst the highest in the world. The development of a database\\u000a of subduction-zone strong-motion recordings is, therefore, of great importance for ground-motion prediction in this region.\\u000a Accelerograms recorded by the different networks operators in Peru and Chile have been compiled and processed in a uniform\\u000a manner, and information on the source parameters
Maria C. Arango; Fleur O. Strasser; Julian J. Bommer; Ruben Boroschek; Diana Comte; Hernando Tavera
Strong-motion records from Long Valley Dam during the Mammoth Lakes earthquake sequence of May 1980 are analyzed to determine the main features of the dam's motions. The dam was instrumented with 22 accelerometers on its embankment and in the immediate vicinity, and more than 60 high-quality, long-duration accelerograms were recorded for the three largest earthquakes of the sequence. Free-field responses are compared with embankment responses to help establish the amplification of the structural motions and to identify modes of vibration of the structure.
Fedock, Joseph, J.
Strong motion recordings of the 2008/12/23 earthquake in Northern Italy: another case of very weak motion?
NASA Astrophysics Data System (ADS)
On December 23 2008 an earthquake of magnitude ML=5.1 (INGV) Mw=5.4 (INGV-Harvard Global CMT) occurred in northern Italy close to the cities of Parma and Reggio Emilia. The earthquake, with a macroseismic intensity of VI MCS, caused a very slight damage (some tens of unusable buildings and some hundreds of damaged buildings), substantially lower than the damage estimated by the loss simulation scenario currently used by the Italian Civil Protection. Due to the recent upgrading of the Italian strong motion network (RAN), the event has been recorded by a great number of accelerometers (the largest ever obtained in Italy for a single shock): 21 digital and 8 analog instruments with epicentral distances ranging from 16 to 140 km. The comparison of recorded PGA, PGV, Arias intensity, and spectral values with several widely used Ground Motion Prediction Equations (GMPEs) showed much lower ground motion values respect to the empirical predictions (a factor ranging from 4 to 2). A first explanation of the strong differences, in damage and ground motion, between actual data and predictions could be, at a first sight, attributed to the rather high focal depth of 27 km. However, even the adoption of GMPEs accounting for depth of the source and using hypocentral distance (Berge et al 2003, Pousse et al 2005), does not predict large differences in motions, especially at distances larger than 30 km where most of the data are concentrated and where the effect of depth on source-to-site distance is small. At the same time the adoption of the most recent GMPEs (Ambraseys et al 2005, Akkar & bommer 2007) taking into account the different magnitude scaling and the faster attenuation of small magnitudes through magnitude-dependent attenuation, does not show a better agreement with the recorded data. The real reasons of the above mentioned discrepancies need to be further investigated, however a possible explanation could be a low source rupture velocity, likewise the 2002 Molise earthquake that also generated very weak motions. Another explanation comes from the fact that the moment magnitude estimated by the INGV network on the basis of body-waves instead of surface-waves used by Harvard CMT, is 4.9 and not 5.4, providing a much better fit of recorded ground motions with GMPEs.
Sabetta, F.; Zambonelli, E.
Ion motion and finite temperature effect on relativistic strong plasma waves
The influence of motion of ions and electron temperature on nonlinear one-dimensional plasma waves with velocity close to the speed of light in vacuum is investigated. It is shown that although the wave-breaking field weakly depends on the mass of ions, the nonlinear relativistic wavelength essentially changes. The nonlinearity leads to the increase of the strong plasma wavelength, while the
Arsen G. Khachatryan
Strong ground-motion prediction from Stochastic-dynamic source models
In the absence of sufficient data in the very near source, predictions of the intensity and variability of ground motions from future large earthquakes depend strongly on our ability to develop realistic models of the earthquake source. In this article we simulate near-fault strong ground motion using dynamic source models. We use a boundary integral method to simulate dynamic rupture of earthquakes by specifying dynamic source parameters (fracture energy and stress drop) as spatial random fields. We choose these quantities such that they are consistent with the statistical properties of slip heterogeneity found in finite-source models of past earthquakes. From these rupture models we compute theoretical strong-motion seismograms up to a frequency of 2 Hz for several realizations of a scenario strike-slip Mw 7.0 earthquake and compare empirical response spectra, spectra obtained from our dynamic models, and spectra determined from corresponding kinematic simulations. We find that spatial and temporal variations in slip, slip rise time, and rupture propagation consistent with dynamic rupture models exert a strong influence on near-source ground motion. Our results lead to a feasible approach to specify the variability in the rupture time distribution in kinematic models through a generalization of Andrews' (1976) result relating rupture speed to apparent fracture energy, stress drop, and crack length to 3D dynamic models. This suggests that a simplified representation of dynamic rupture may be obtained to approximate the effects of dynamic rupture without having to do full dynamic simulations.
Guatteri, M.; Mai, P. M.; Beroza, G. C.; Boatwright, J.
Simulation of strong earthquake motion by explosions � experiments at the Lyaur testing range in Tajikistan
Strong motion data of 10 controlled explosion experiments conducted in 1977 at the Lyaur testing range in the Republic of Tajikistan are revisited. The explosions were detonated in arrays, with time delay between detonation of array lines. Ground accelerations, as large as , 1.6g, were recorded at 4 sites by SMA-1 accelerographs. The records were recently digitized and processed with
S. Kh; M. D. Trifunac
Simulation of strong earthquake motion by explosions � experiments at the Lyaur testing range in Tajikistan
Strong motion data of 10 controlled explosion experiments conducted in 1977 at the Lyaur testing range in the Republic of Tajikistan are revisited. The explosions were detonated in arrays, with time delay between detonation of array lines. Ground accelerations, as large as ?1.6g, were recorded at 4 sites by SMA-1 accelerographs. The records were recently digitized and processed with modern
S. Kh. Negmatullaev; M. I. Todorovska; M. D. Trifunac
Synthesis of strong motions by using an aftershock record as the Green's function
NASA Astrophysics Data System (ADS)
A method to synthesize strong ground motions by using aftershock records as Green's functions was developed to reproduce the high-frequency components of the main shock. We call it a random slip model, and have applied it to three large earthquakes, the east off-Izu Peninsula earthquake of 1980 ( M = 6.7), the off-Urakawa earthquake of 1982 ( M = 7.1) and the Central Japan Sea earthquake of 1983 ( M = 7.7). Seismic intensities at six stations during the earthquakes analyzed here were from I to VI on the JMA (Japan Meteorological Agency) scale. All the aftershock seismograms used as Green's functions in the present study were recorded by velocity-type strong-motion seismographs with a large dynamic range over a wide frequency range. A few main-shock seismograms were recorded by seismographs similar to those mentioned above; the rest were recorded by other types of strong-motion seismographs e.g. the SMAC (strong-motion accelerograph) and JMA strong-motion seismographs. From a comparison of the synthetic with the observed seismograms of the main shock, we conclude the following: (1) Using the record of an adequate aftershock and an adequate source model, we can satisfactorily reproduce any observed seismogram of the main shock. (2) The conditions for an adequate aftershock are that the hypocenter is located in the central part of the main-shock fault, and that the mechanism is similar to that of the main shock. (3) The high-frequency waves contained in the main-shock seismograms are reproduced by the random slip model up to 5 Hz for records at every station. (4) By considering a multiple-shock source model, we can fit the synthetic to the observed seismograms for two large earthquakes with magnitudes ( Mj) larger than 7.
Murumatu, I.; Ohnuma, H.
Strong Earthquake Motion Estimates for Three Sites on the U.C. Riverside Campus
The approach of the Campus Earthquake Program (CEP) is to combine the substantial expertise that exists within the UC system in geology, seismology, and geotechnical engineering, to estimate the earthquake strong motion exposure of UC facilities. These estimates draw upon recent advances in hazard assessment, seismic wave propagation modeling in rocks and soils, and dynamic soil testing. The UC campuses currently chosen for application of our integrated methodology are Riverside, San Diego, and Santa Barbara. The procedure starts with the identification of possible earthquake sources in the region and the determination of the most critical fault(s) related to earthquake exposure of the campus. Combined geological, geophysical, and geotechnical studies are then conducted to characterize each campus with specific focus on the location of particular target buildings of special interest to the campus administrators. We drill and geophysically log deep boreholes next to the target structure, to provide direct in-situ measurements of subsurface material properties, and to install uphole and downhole 3-component seismic sensors capable of recording both weak and strong motions. The boreholes provide access below the soil layers, to deeper materials that have relatively high seismic shear-wave velocities. Analyses of conjugate downhole and uphole records provide a basis for optimizing the representation of the low-strain response of the sites. Earthquake rupture scenarios of identified causative faults are combined with the earthquake records and with nonlinear soil models to provide site-specific estimates of strong motions at the selected target locations. The predicted ground motions are shared with the UC consultants, so that they can be used as input to the dynamic analysis of the buildings. Thus, for each campus targeted by the CEP project, the strong motion studies consist of two phases, Phase 1--initial source and site characterization, drilling, geophysical logging, installation of the seismic station, and initial seismic monitoring, and Phase 2--extended seismic monitoring, dynamic soil testing, calculation of estimated site-specific earthquake strong motions at depth and at the surface, and, where applicable, estimation of the response of selected buildings to the CEP-estimated strong motions.
Archuleta, R.; Elgamal, A.; Heuze, F.; Lai, T.; Lavalle, D.; Lawrence, B.; Liu, P.C.; Matesic, L.; Park, S.; Riemar, M.; Steidl, J.; Vucetic, M.; Wagoner, J.; Yang, Z.
Strong earthquake motion estimates for three sites on the U.C. San Diego campus
The approach of the Campus Earthquake Program (CEP) is to combine the substantial expertise that exists within the UC system in geology, seismology, and geotechnical engineering, to estimate the earthquake strong motion exposure of UC facilities. These estimates draw upon recent advances in hazard assessment, seismic wave propagation modeling in rocks and soils, and dynamic soil testing. The UC campuses currently chosen for application of our integrated methodology are Riverside, San Diego, and Santa Barbara. The procedure starts with the identification of possible earthquake sources in the region and the determination of the most critical fault(s) related to earthquake exposure of the campus. Combined geological, geophysical, and geotechnical studies are then conducted to characterize each campus with specific focus on the location of particular target buildings of special interest to the campus administrators. We drill, sample, and geophysically log deep boreholes next to the target structure, to provide direct in-situ measurements of subsurface material properties, and to install uphole and downhole 3-component seismic sensors capable of recording both weak and strong motions. The boreholes provide access below the soil layers, to deeper materials that have relatively high seismic shear-wave velocities. Analyses of conjugate downhole and uphole records provide a basis for optimizing the representation of the low-strain response of the sites. Earthquake rupture scenarios of identified causative faults are combined with the earthquake records and with nonlinear soil models to provide site-specific estimates of strong motions at the selected target locations. The predicted ground motions are shared with the UC consultants, so that they can be used as input to the dynamic analysis of the buildings. Thus, for each campus targeted by the CEP project, the strong motion studies consist of two phases, Phase 1--initial source and site characterization, drilling, geophysical logging, installation of the seismic station, and initial seismic monitoring, and Phase 2--extended seismic monitoring, dynamic soil testing, calculation of estimated site-specific earthquake strong motions at depth and at the surface, and , where applicable, estimation of the response of selected buildings to the CEP-estimated strong motions.
Day, S; Doroudian, M; Elgamal, A; Gonzales, S; Heuze, F; Lai, T; Minster, B; Oglesby, D; Riemer, M; Vernon, F; Vucetic, M; Wagoner, J; Yang, Z
Parallel PSM\\/FDM Hybrid Simulation of Ground Motions from the 1999 Chi-Chi, Taiwan, Earthquake
-- A new technique for the parallel computing of 3-D seismic wave propagation simulation is developed by hybridizing the Fourier pseudospectral method (PSM) and the finite-difference method (FDM). This PSM\\/FDM hybrid offers a good speed-up rate using a large number of processors. To show the feasibility of the hybrid, a numerical 3-D simulation of strong ground motion was conducted for
New Hybridized Surface Wave Approach for Geotechnical Modeling of Shear Wave Velocity at Strong Motion Recording Stations
NASA Astrophysics Data System (ADS)
Strong motion recording (SMR) networks often have little or no shear wave velocity measurements at stations where characterization of site amplification and site period effects is needed. Using the active Spectral Analysis of Surface Waves (SASW) method, and passive H/V microtremor method we have investigated nearly two hundred SMR sites in California, Alaska, Japan, Australia, China and Taiwan. We are conducting these studies, in part, to develop a new hybridized method of site characterization that utilizes a parallel array of harmonic-wave sources for active-source SASW, and a single long period seismometer for passive-source microtremor measurement. Surface wave methods excel in their ability to non-invasively and rapidly characterize the variation of ground stiffness properties with depth below the surface. These methods are lightweight, inexpensive to deploy, and time-efficient. They have been shown to produce accurate and deep soil stiffness profiles. By placing and wiring shakers in a large parallel circuit, either side-by-side on the ground or in a trailer-mounted array, a strong in-phase harmonic wave can be produced. The effect of arraying many sources in parallel is to increase the amplitude of waves received at far-away spaced seismometers at low frequencies so as to extend the longest wavelengths of the captured dispersion curve. The USGS system for profiling uses this concept by arraying between two and eight electro-mechanical harmonic-wave shakers. With large parallel arrays of vibrators, a dynamic force in excess of 1000 lb can be produced to vibrate the ground and produce surface waves. We adjust the harmonic wave through a swept-sine procedure to profile surface wave dispersion down to a frequency of 1 Hz and out to surface wave-wavelengths of 200-1000 meters, depending on the site stiffness. The parallel-array SASW procedure is augmented using H/V microtremor data collected with the active source turned off. Passive array microtremor data reveal the natural and resonance characteristics of the ground by capturing persistent natural vibrations. These microtremors are the result of the interaction of surface waves arriving from distant sources and the stiffness structure of the site under investigation. As such, these resonance effects are effective in constraining the layer thicknesses of the SASW shear wave velocity structure and aid in determining the depth of the deepest layer. Together, the hybridized SASW and H/V procedure provides a complete data set for modeling the geotechnical aspects of ground amplification of earthquake motions. Data from these investigations are available at http://walrus.wr.usgs.gov/geotech.
Kayen, R.; Carkin, B.; Minasian, D.
the correlation of landslide and strong ground motion in Ms8.0 Wenchuan earthquake
NASA Astrophysics Data System (ADS)
slope failure trigged by strong earthuqake is main factor to bring great losses in Ms. 8.0 Wenchuan earthquake occurred on May 12, 2008, in Sichuan province, south-western China. According to the site investigation, about twenty shousands of slopes were found to lose their stabilities, main including landslides, collapsed rock, debris and ground crack, etc. The paper presents a statistic model discribing the correlation between landslide and strong ground motion.In this model, slope stability index (SSI) is defined based on the spatial distribution characteristics of peak ground acceleration (PGA), peak ground velocity (PGV), peak ground displacement (PGD) and earthuqake intensity(EI). SSI is related to not only slope parameters such as height, slope natural angle, rock hardness and attitude of stratum, but also PGA or PGV or PGD. This index had successfully been used to quickly assess the slope failure under strong ground motion in this Wenchuan earthquake.
Tang, Aping
Development of an Earthquake Early Warning System Using Real-Time Strong Motion Signals
As urbanization progresses worldwide, earthquakes pose serious threat to lives and properties for urban areas near major active faults on land or subduction zones offshore. Earthquake Early Warning (EEW) can be a useful tool for reducing earthquake hazards, if the spatial relation between cities and earthquake sources is favorable for such warning and their citizens are properly trained to respond to earthquake warning messages. An EEW system forewarns an urban area of forthcoming strong shaking, normally with a few sec to a few tens of sec of warning time, i.e., before the arrival of the destructive S-wave part of the strong ground motion. Even a few second of advanced warning time will be useful for pre-programmed emergency measures for various critical facilities, such as rapid-transit vehicles and high-speed trains to avoid potential derailment; it will be also useful for orderly shutoff of gas pipelines to minimize fire hazards, controlled shutdown of high-technological manufacturing operations to reduce potential losses, and safe-guarding of computer facilities to avoid loss of vital databases. We explored a practical approach to EEW with the use of a ground-motion period parameter ?c and a high-pass filtered vertical displacement amplitude parameter Pd from the initial 3 sec of the P waveforms. At a given site, an earthquake magnitude could be determined from ?c and the peak ground-motion velocity (PGV) could be estimated from Pd. In this method, incoming strong motion acceleration signals are recursively converted to ground velocity and displacement. A P-wave trigger is constantly monitored. When a trigger occurs, ?c and Pd are computed. The earthquake magnitude and the on-site ground-motion intensity could be estimated and the warning could be issued. In an ideal situation, such warnings would be available within 10 sec of the origin time of a large earthquake whose subsequent ground motion may last for tens of seconds.
Wu, Yih-Min; Kanamori, Hiroo
Hanford strong motion accelerometer network: A summary of the first year of operation
The Hanford Seismic Monitoring Network consists of two designs of equipment and sites: seismometer sites and strong motion accelerometer (SMA) sites. Seismometer sites are designed to locate earthquakes on and near the Hanford Site and determine their magnitude and hypocenter location. The US Department of Energy (DOE) Order 5480.28, Natural Phenomena Hazards (DOE 1993) requires that facilities or sites that have structures or components in Performance Category 2 with hazardous material, and all Performance Category 3 and 4 facilities shall have instrumentation or other means to detect and record the occurrence and severity of seismic events. In order to comply with DOE Order 5480.28, the Hanford Seismic Monitoring Network seismometer sites needed to be complemented with strong motion accelerometers to record the ground motion at specific sites. The combined seismometer sites and strong motion accelerometer sites provide the Hanford Site with earthquake information to comply with DOE Order 5480.28. The data from these instruments will be used by the PHMC staff to assess the damage to facilities following a significant earthquake.
Conrads, T.J.
Comparison of damping in buildings under low-amplitude and strong motions
This paper presents a comprehensive assessment of damping values and other dynamic characteristics of five buildings using strong-motion and low-amplitude (ambient vibration) data. The strong-motion dynamic characteristics of five buildings within the San Francisco Bay area are extracted from recordings of the 17 October 1989 Loma Prieta earthquake (LPE). Ambient vibration response characteristics for the same five buildings were inferred using data collected in 1990 following LPE. Additional earthquake data other than LPE for one building and ambient vibration data collected before LPE for two other buildings provide additional confirmation of the results obtained. For each building, the percentages of critical damping and the corresponding fundamental periods determined from low-amplitude test data are appreciably lower than those determined from strong-motion recordings. These differences are attributed mainly to soil-structure interaction and other non-linear behavior affecting the structures during strong shaking. Significant contribution of radiation damping to the effective damping of a specific building is discussed in detail.
Celebi, M.
Chapter A. The Loma Prieta, California, Earthquake of October 17, 1989 - Strong Ground Motion
Strong ground motion generated by the Loma Prieta, Calif., earthquake (MS~7.1) of October 17, 1989, resulted in at least 63 deaths, more than 3,757 injuries, and damage estimated to exceed $5.9 billion. Strong ground motion severely damaged critical lifelines (freeway overpasses, bridges, and pipelines), caused severe damage to poorly constructed buildings, and induced a significant number of ground failures associated with liquefaction and landsliding. It also caused a significant proportion of the damage and loss of life at distances as far as 100 km from the epicenter. Consequently, understanding the characteristics of the strong ground motion associated with the earthquake is fundamental to understanding the earthquake's devastating impact on society. The papers assembled in this chapter address this problem. Damage to vulnerable structures from the earthquake varied substantially with the distance from the causative fault and the type of underlying geologic deposits. Most of the damage and loss of life occurred in areas underlain by 'soft soil'. Quantifying these effects is important for understanding the tragic concentrations of damage in such areas as Santa Cruz and the Marina and Embarcadero Districts of San Francisco, and the failures of the San Francisco-Oakland Bay Bridge and the Interstate Highway 880 overpass. Most importantly, understanding these effects is a necessary prerequisite for improving mitigation measures for larger earthquakes likely to occur much closer to densely urbanized areas in the San Francisco Bay region. The earthquake generated an especially important data set for understanding variations in the severity of strong ground motion. Instrumental strong-motion recordings were obtained at 131 sites located from about 6 to 175 km from the rupture zone. This set of recordings, the largest yet collected for an event of this size, was obtained from sites on various geologic deposits, including a unique set on 'soft soil' deposits (artificial fill and bay mud). These exceptional ground-motion data are used by the authors of the papers in this chapter to infer radiation characteristics of the earthquake source, identify dominant propagation characteristics of the Earth?s crust, quantify amplification characteristics of near-surface geologic deposits, develop general amplification factors for site-dependent building-code provisions, and revise earthquake-hazard assessments for the San Francisco Bay region. Interpretations of additional data recorded in well-instrumented buildings, dams, and freeway overpasses are provided in other chapters of this report.
Edited by Borcherdt, Roger D.
Dense Strong Motion Seismograph Networks in Canada: Opportunities and Applications. (Invited)
NASA Astrophysics Data System (ADS)
Strong motion monitoring has undergone a revolution in Canada in recent years. Most analogue, non-communicating instruments have been replaced with modern, smart digital instruments that provide information in real-time. These new instruments have on-board computing capabilities and can serve multiple purposes when connected in networks with fast Internet based telemetry. As of 2010, the Geological Survey of Canada operates 110 strong motion instruments (Internet Acclerometers or IA=s) across Canada, most of which are deployed in or near the urban centres of high seismic hazard in southwest British Columbia. Partner organisations operate an additional 70 strong motion instruments monitoring critical infrastructure in western Canada. These instruments and data serve multiple purposes: 1. They help to fill the still sparse data-base of strong ground motions required for seismic engineering and hazard and risk assessment in general. 2. Recordings of small, moderate (and large) earthquakes can be utilised for earthquake site response studies - mapping the variation in shaking across urban areas and the effects of surface geology, sedimentary basins, and topography. 3. They contribute to the development of real-time warning systems. 4. They contribute to situational awareness after a major earthquake (e.g., shaking maps). 5. Their data can be integrated with structural monitoring systems to aide in the rapid assessment of critical infrastructure and life lines in the aftermath of a large earthquake. These applications require a sufficiently high density of stations in a high earthquake risk area and as well a new type of smart instrument which can provide a tailored parameter set describing the nature and severity of earthquake ground motion in real time and in a form suitable as input for engineering models. The real time transmittal of data into easily accessible displays can facilitate post earthquake response and inspection, and can enable emergency funding agencies to focus recovery efforts. Here, we provide an overview of how the strong motion network in the high-risk region of southwest British Columbia operates and present some examples of new opportunities and applications.
Cassidy, J. F.; Rosenberger, A.; Rogers, G. C.; Huffman, S.
Before and after retrofit - response of a building during ambient and strong motions
This paper presents results obtained from ambient vibration and strong-motion responses of a thirteen-story, moment-resisting steel framed Santa Clara County Office Building (SCCOB) before being retrofitted by visco-elastic dampers and from ambient vibration response following the retrofit. Understanding the cumulative structural and site characteristics that affect the response of SCCOB before and after the retrofit is important in assessing earthquake hazards to other similar buildings and decision making in retrofitting them. The results emphasize the need to better evaluate structural and site characteristics in developing earthquake resisting designs that avoid resonating effects. Various studies of the strong-motion response records from the SCCOB during the 24 April 1984 (MHE) Morgan Hill (MS = 6.1), the 31 March 1986 (MLE) Mt. Lewis (MS = 6.1) and the 17 October 1989 (LPE) Loma Prieta (MS = 7.1) earthquakes show that the dynamic characteristics of the building are such that it (a) resonated (b) responded with a beating effect due to close-coupling of its translational and torsional frequencies, and (c) had a long-duration response due to low-damping. During each of these earthquakes, there was considerable contents damage and the occupants felt the rigorous vibration of the building. Ambient tests of SCCOB performed following LPE showed that both translational and torsional periods of the building are smaller than those derived from strong motions. Ambient tests performed following the retrofit of the building with visco-elastic dampers show that the structural fundamental mode frequency of the building has increased. The increased frequency implies a stiffer structure. Strong-motion response of the building during future earthquakes will ultimately validate the effectiveness of the retrofit method.This paper presents results obtained from ambient vibration and strong-motion responses of a thirteen-story, moment-resisting steel framed Santa Clara County Office Building (SCCOB) before being retrofitted by visco-elastic dampers and from ambient vibration response following the retrofit. Understanding the cumulative structural and site characteristics that affect the response of SCCOB before and after the retrofit is important in assessing earthquake hazards to other similar buildings and decision making in retrofitting them. The results emphasize the need to better evaluate structural and site characteristics in developing earthquake resisting designs that avoid resonating effects. Various studies of the strong-motion response records from the SCCOB during the 24 April 1984 (MHE) Morgan Hill (Ms = 6.1), the 31 March 1986 (MLE) Mt. Lewis (Ms = 6.1) and the 17 October 1989(LPE) Loma Prieta (Ms = 7.1) earthquakes show that the dynamic characteristics of the building are such that it (a) resonated (b) responded with a beating effect due to close-coupling of its translational and torsional frequencies, and (c) had a long-duration response due to low-damping. During each of these earthquakes, there was considerable contents damage and the occupants felt the rigorous vibration of the building. Ambient tests of SCCOB performed following LPE showed that both translational and torsional periods of the building are smaller than those derived from strong motions. Ambient tests performed following the retrofit of the building with visco-elastic dampers show that the structural fundamental mode frequency of the building has increased. The increased frequency implies a stiffer structure. Strong-motion response of the building during future earthquakes will ultimately validate the effectiveness of the retrofit method.
Celebi, M.; Liu, H. -P.
A preliminary investigation of strong-motion data from the French Antilles
NASA Astrophysics Data System (ADS)
Strong-motion networks have been operating in the Caribbean region since the 1970s, however, until the mid-1990s only a few analogue stations were operational and the quantity of data recorded was very low. Since the mid-1990s, digital accelerometric networks have been established on islands within the region. At present there are thought to be about 160 stations operating in this region with a handful on Cuba, 65 on the French Antilles (mainly Guadeloupe and Martinique), eight on Jamaica, 78 on Puerto Rico (plus others on adjacent islands) and four on Trinidad. After briefly summarising the available data from the Caribbean islands, this article is mainly concerned with analysing the data that has been recorded by the networks operating on the French Antilles in terms of their distribution with respect to magnitude, source-to-site distance, focal depth and event type; site effects at certain stations; and also with respect to their predictability by ground motion estimation equations developed using data from different regions of the world. More than 300 good quality triaxial acceleration time-histories have been recorded on Guadeloupe and Martinique at a large number of stations from earthquakes with magnitudes larger than 4.8, however, most of the records are from considerable source-to-site distances. From the data available it is found that many of the commonly-used ground motion estimation equations for shallow crustal earthquakes poorly estimate the observed ground motions on the two islands; ground motions on Guadeloupe and Martinique have smaller amplitudes and are more variable than expected. This difference could be due to regional dependence of ground motions because of, for example, differing tectonics or crustal structures or because the ground motions so far recorded are, in general, from smaller earthquakes and greater distances than the range of applicability of the investigated equations.
Douglas, John; Bertil, Didier; Roull�, Agathe; Dominique, Pascal; Jousset, Philippe
STRONG-MOTION SEISMOGRAPH NETWORK OPERATED BY NIED: K-NET AND KiK-net
After the 1995 Hyogoken-Nanbu earthquake, NIED (National Research Institute for Earth Science and Disaster Prevention) installed the K-NET that uniformly covers all Japan with more than one thousand strong-motion accelerometers on the ground surface. In addition to the K-NET, NIED constructed an uphole\\/downhole observation network, KiK-net, with approximately 669 stations. Each KiK-net station has a borehole of 100 m or
Shin AOI; Takashi KUNUGI; Hiroyuki FUJIWARA
A novel strong-motion seismic network for community participation in earthquake monitoring
The Quake-Catcher Network (QCN) is breaking new ground in seismology by combining new micro-electro-mechanical systems (MEMS) technology with volunteer seismic station distributed computing. Rather than distributing just computations, the QCN allows volunteers to participate in scientific data collection and computation. Using these innovative tools, QCN will increase the number of strong-motion observations for improved earthquake detection and analysis in California,
Elizabeth Cochran; Jesse Lawrence; Carl Christensen; Angela Chung
Comparison between staggered grid finite difference method and stochastic method in simulating strong ground motions
Strong ground motion of an earthquake is simulated by using both staggered grid finite difference method (FDM) and stochastic\\u000a method, respectively. The acceleration time histories obtained from the both ways and their response spectra are compared.\\u000a The result demonstrates that the former is adequate to simulate the low-frequency seismic wave; the latter is adequate to\\u000a simulate the high-frequency seismic wave.
Man-Sheng Wang; Hui Jiang; Yu-Xian Hu
Joint inversion of strong motion and geodetic data for the source process of the 2003 Tokachi-oki, Hokkaido, earthquake
The strong motion and geodetic data were individually inverted for the source process of the 2003 Tokachi-oki, Hokkaido, earthquake with a hypocenter 25 km deep and a fault plane above the subducting Pacific slab. Both the results show a simple slip distribution with a single major asperity, but the strong motion inversion may include a trade-off between slip location and
Kazuki Koketsu; Kazuhito Hikima; S. Miyazaki; S. Ide
We have used 24 broadband teleseismic and 48 components of local strong-motion velocity records of the 1989 Loma Prieta earthquake in a formal inversion to determine the temporal and spatial distribution of slip. Separate inversions of the teleseismic data (periods of 3 to 30 sec) or strong-motion data (periods of 1 to 5 sec) result in similar models. The data
The near-source strong-motion accelerograms recorded by an experimental array in Tangshan, China
A joint research project on strong-motion earthquake studies between the People's Republic of China and the United States is in progress. As a part of this project, an experimental strong-motion array, consisting of twelve Kinemetrics PDR-1 Digital Event Recorders, was deployed in the meizoseismal area of the Ms = 7.8 Tangshan earthquake of July 28, 1976. These instruments have automatic gain ranging, a specified dynamic range of 102 dB, a 2.5 s pre-event memory, programmable triggering, and are equipped with TCG-1B Time Code Generators with a stability of 3 parts in 107 over a range of 0-50??C. In 2 y of operation beginning July, 1982 a total of 603 near-source 3-component accelerograms were gathered from 243 earthquakes of magnitude ML = 1.2-5.3. Most of these accelerograms have recorded the initial P-wave. The configuration of the experimental array and a representative set of near-source strong-motion accelerograms are presented in this paper. The set of accelerograms exhibited were obtained during the ML = 5.3 Lulong earthquake of October 19, 1982, when digital event recorders were triggered. The epicentral distances ranged from 4 to 41 km and the corresponding range of peak horizontal accelerations was 0.232g to 0.009g. A preliminary analysis of the data indicates that compared to motions in the western United States, the peak acceleration attenuates much more rapidly in the Tangshan area. The scaling of peak acceleration with magnitude, however, is similar in the two regions. Data at more distant sites are needed to confirm the more rapid attenuation. ?? 1985.
Peng, K.; Xie, L.; Li, S.; Boore, D. M.; Iwan, W. D.; Teng, T. L.
Translational motion of two interacting bubbles in a strong acoustic field.
Using the Lagrangian formalism, equations of radial and translational motions of two coupled spherical gas bubbles have been derived up to terms of third order in the inverse distance between the bubbles. The equations of radial pulsations were then modified, for the purpose of allowing for effects of liquid compressibility, using Keller-Miksis' approach, and the equations of translation were added by viscous forces in the form of the Levich drag. This model was then used in a numerical investigation of the translational motion of two small, driven well below resonance, bubbles in strong acoustic fields with pressure amplitudes exceeding 1 bar. It has been found that, if the forcing is strong enough, the bubbles form a bound pair with a steady spacing rather than collide and coalesce, as classical Bjerknes theory predicts. Moreover, the viscous forces cause skewness in the system, which results in self-propulsion of the bubble pair. The latter travels as a unit along the center line in a direction that is determined by the ratio of the initial bubble radii. The results obtained are of immediate interest for understanding and modeling collective bubble phenomena in strong fields, such as acoustic cavitation streamers. PMID:11497693
Doinikov, A A
Wind speed and direction shears with associated vertical motion during strong surface winds
NASA Technical Reports Server (NTRS)
Strong surface winds recorded at the NASA 150-Meter Ground Winds Tower facility at Kennedy Space Center, Florida, are analyzed to present occurrences representative of wind shear and vertical motion known to be hazardous to the ascent and descent of conventional aircraft and the Space Shuttle. Graphical (percentage frequency distributions) and mathematical (maximum, mean, standard deviation) descriptions of wind speed and direction shears and associated updrafts and downdrafts are included as functions of six vertical layers and one horizontal distance for twenty 5-second intervals of parameters sampled simultaneously at the rate of ten per second during a period of high surface winds.
Alexander, M. B.; Camp, D. W.
Strong ground motions of the 2009 L'Aquila earthquake: modeling and scenario simulations
NASA Astrophysics Data System (ADS)
On April 6, 2009 a Mw 6.3 earthquake struck the L'Aquila city, one of the largest urban centers in the Abruzzo region (Central Italy), causing a large number of casualties and damage in the town and surrounding villages. The earthquake has been recorded by several digital stations of the Italian Strong-Motion Network. The collected records represent a unique dataset in Italy in terms of number and quality of records, azimuthal coverage and presence of near-fault recordings. Soon after the earthquake the damage in the epicentral area was also assessed providing macroseismic intensity estimates, in MCS scale, for 314 localities (I ?5). Despite the moderate magnitude of the L'Aquila earthquake, the strong-motion and macroseismic data in the vicinity of the fault depict a large variability of the observed shaking and damage. In this study we present broadband (0.1 - 10 Hz) ground motion simulations of the 2009 L'Aquila earthquake to be used for engineering purposes in the region. We utilize Hybrid Integral-Composite (HIC, Gallovi? and Broke�ov�, 2007) approach based on a k-square kinematic rupture model, combining low-frequency coherent and high-frequency incoherent source radiation and providing omega-squared source spectral decay. We first model the recorded seismograms in order to calibrate source parameters and to assess the capabilities of the broadband simulation model. To this end, position and slip amount of the two main asperities, the largest asperity time delay and the rupture velocity distribution on the fault is constrained, based on the low-frequency slip inversion result. Synthetic Green's functions are calculated in a 1D-layered crustal model including 1D soil profiles to account for site-specific response (where available). The goodness-of-fit is evaluated in time (peak values and duration) and frequency domains (elastic and inelastic response spectra) and shows a remarkable agreement between observed and simulated data at most of the stations. The results show that not only the local site effects improve the modeling results, but also that the spatial broadband ground-motion variability is to large extent controlled by the rupture kinematics revealed by the low-frequency inversion. We simulate the ground motion at a grid of sites and compared the observed macroseismic intensity distribution with that obtained applying ground-motion to intensity conversion equations to the synthetic data. We find that the spectral ordinates at periods larger than 2s are well correlated with the macroseismic intensity pattern observed in the epicentral area. Finally, we compare the synthetic ground-motion parameters with estimates from several empirical ground motion prediction equations (GMPEs). The comparison highlights potential drawbacks in using GMPEs to validate simulated motions and/or when used for engineering purposes.
Gallovi?, F.; Ameri, G.; Pacor, F.
Simulation of strong ground motions caused by the 2004 off the Kii peninsula earthquakes
NASA Astrophysics Data System (ADS)
Strong ground motions caused by the Mj 7.4 2004 earthquake that occurred in the Nankai Trough to the southeast of the Kii Peninsula, Japan are simulated by a three-dimensional (3D) finite-difference method (FDM) using a fault-rupture model obtained by inversion of teleseismic seismograms and a 3D subsurface structure model for central Japan. Through simulations of the foreshock (Mj 7.1), the structural model is refined by comparison with observations, and the modified model is used to simulate the mainshock. The simulation provides a reasonable reproduction of the ground motions caused by the mainshock, including site amplification effects in the sedimentary basins of Osaka and Noubi. However, the current simulation model has limitations in producing the large and extended ground motion due to long-period Love waves in the Kanto Plain, as the model does not account for the sharp frequency selectivity for Love waves in the surficial structure of the Bouso Peninsula. It therefore appears necessary to develop a better model for longer-period waves.
Hayakawa, T.; Furumura, T.; Yamanaka, Y.
On the Effects of Non-planar Geometry for Blind Thrust Faults on Strong Ground Motion
NASA Astrophysics Data System (ADS)
We quantify the effects of complex fault geometry on low-frequency (<1 Hz) strong ground motion using numerical modeling of dynamic rupture. Our tests include the computation of synthetic seismograms for several simple rupture scenarios with planar and curved fault approximations of the 1994 Northridge earthquake. We use the boundary integral equation method (BIEM) to compute the dynamic rupture process, which includes the normal stress effects along the curved fault geometries. The wave propagation and computation of synthetic seismograms are modeled using a fourth-order finite-difference method (FDM). The near-field ground motion is significantly affected by the acceleration, deceleration and arrest of rupture due to the curvature of the faults, as well as the variation in directivity of the rupture. For example, a 6-km-long hanging-wall or footwall splay with a maximum offset of 1 km can change 1-Hz peak velocities by up to a factor of 2-3 near the fault. Our tests suggest that the differences in waveform are larger on the hanging wall compared to those on the footwall, although the differences in amplitude are larger in the forward rupture direction (footwall). The results imply that kinematic ground motion estimates may be biased by the omission of dynamic rupture effects and even relatively gentle variation in fault geometry, and even for long-period waves.
Aochi, Hideo; Olsen, Kim B.
More than 250 strong-motion accelerograph stations were triggered by the Whittier Narrows, California earthquake of 1 October 1987. Considering the number of multichannel structural stations in the area of strong shaking, this set of records is one of the more significant in history. Three networks, operated by the U. S. Geological Survey, the California Division of Mines and Geology, and the University of Southern California produced the majority of the records. The excellent performance of the instruments in these and the smaller arrays is attributable to the quality of the maintenance programs. Readiness for a magnitude 8 event is directly related to these maintenance programs. Prior to computer analysis of the analog film records, a number of important structural resonant modes can be identified, and frequencies and simple mode shapes have been scaled.
Brady, A. G.; Etheredge, E. C.; Porcella, R. L.
Modelling strong seismic ground motion: three-dimensional loading path versus wavefield polarization
NASA Astrophysics Data System (ADS)
Seismic waves due to strong earthquakes propagating in surficial soil layers may both reduce soil stiffness and increase the energy dissipation into the soil. To investigate seismic wave amplification in such cases, past studies have been devoted to one-directional shear wave propagation in a soil column (1D-propagation) considering one motion component only (1C-polarization). Three independent purely 1C computations may be performed ('1D-1C' approach) and directly superimposed in the case of weak motions (linear behaviour). This research aims at studying local site effects by considering seismic wave propagation in a 1-D soil profile accounting for the influence of the 3-D loading path and non-linear hysteretic behaviour of the soil. In the proposed '1D-3C' approach, the three components (3C-polarization) of the incident wave are simultaneously propagated into a horizontal multilayered soil. A 3-D non-linear constitutive relation for the soil is implemented in the framework of the Finite Element Method in the time domain. The complex rheology of soils is modelled by mean of a multisurface cyclic plasticity model of the Masing-Prandtl-Ishlinskii-Iwan type. The great advantage of this choice is that the only data needed to describe the model is the modulus reduction curve. A parametric study is carried out to characterize the changes in the seismic motion of the surficial layers due to both incident wavefield properties and soil non-linearities. The numerical simulations show a seismic response depending on several parameters such as polarization of seismic waves, material elastic and dynamic properties, as well as on the impedance contrast between layers and frequency content and oscillatory character of the input motion. The 3-D loading path due to the 3C-polarization leads to multi-axial stress interaction that reduces soil strength and increases non-linear effects. The non-linear behaviour of the soil may have beneficial or detrimental effects on the seismic response at the free surface, depending on the energy dissipation rate. Free surface time histories, stress-strain hysteresis loops and in-depth profiles of octahedral stress and strain are estimated for each soil column. The combination of three separate 1D-1C non-linear analyses is compared to the proposed 1D-3C approach, evidencing the influence of the 3C-polarization and the 3-D loading path on strong seismic motions.
Santisi d'Avila, Maria Paola; Lenti, Luca; Semblat, Jean-Fran�ois
Characterized Source Modeling of Surface and Subsurface Faulting for Strong Motion Prediction
NASA Astrophysics Data System (ADS)
In order to improve current approaches for near-source ground motion prediction, we construct a source characterization for surface and subsurface earthquakes based on the dynamic rupture simulation. We attempt to explain the paradox that ground motions caused by subsurface rupture seem to be larger than those of surface rupture at a period of 1 second (Somerville, 2003). Recent studies of kinematic source models show larger stress drop for subsurface asperities and smaller stress drop for surface asperities (e.g., Kagawa et al., 2004). Our dynamic rupture simulation shows that the fracture energy is gradually increasing from the subsurface- and surface-rupture earthquakes as a function of the stress intensity factor (e.g., Mai et al., 2005). Using the differences of stress drop, the scaling slope of the fracture energy Gc and stress intensity factors, we interpret that asperities of surface-rupture earthquakes require larger Dc than subsurface-rupture earthquakes for a given effective stress, which is defined as a peak-to-peak stress in the time domain. We construct Kostrov-like slip-velocity functions as functions of effective stress and slip-weakening distance for asperities of surface and subsurface faulting. The surface rupture earthquakes have lower maximum slip-velocity and its peak time is larger due to the smaller effective stress and larger fracture energy. The subsurface rupture earthquakes have larger maximum slip-velocity and its peak time is shorter due to the larger effective stress and smaller fracture energy. We performed strong ground motion simulation using the characterized source model which consists of asperities and background area. The physics-based slip-velocity time functions for the models are examined in comparison with the observed records and simulated motions for the 1992 Landers earthquake (Mw 7.2), a large surface faulting event, and the 1997 Kagoshima earthquake (Mw 6.0), an event that occurred on a previously unknown structure (undefined-subsurface faulting). Near-source ground motion simulations show the applicability of the proposed slip-velocity functions explaining the ground motion differences between the surface and subsurface faulting at a period of 1 second.
Irikura, K.; Miyake, H.; Dalguer, L. A.; Matsushima, S.; Dan, K.; Sato, T.; Kagawa, T.; Mai, P. M.; Somerville, P. G.; Pitarka, A.; Song, S. G.; Beroza, G. C.
Site effects by generalized inversion technique using strong motion recordings of the 2008 Wenchuan earthquake
NASA Astrophysics Data System (ADS)
The generalized inversion of S-wave amplitude spectra from the free-field strong motion recordings of the China National Strong Motion Observation Network System (NSMONS) are used to evaluate the site effects in the Wenchuan area. In this regard, a total of 602 recordings from 96 aftershocks of the Wenchuan earthquake with magnitudes of M3.7- M6.5 were selected as a dataset. These recordings were obtained from 28 stations at a hypocenter distance ranging from 30 km to 150 km. The inversion results have been verified as reliable by comparing the site response at station 62WUD using the Generalized Inversion Technique (GIT) and the Standard Spectral Ratio method (SSR). For all 28 stations, the site predominant frequency F p and the average site amplification in different frequency bands of 1.0-5.0 Hz, 5.0-10.0 Hz and 1.0-10.0 Hz have been calculated based on the inversion results. Compared with the results from the horizontal-to-vertical spectral ratio (HVSR) method, it shows that the HVSR method can reasonably estimate the site predominant frequency but underestimates the site amplification. The linear fitting between the average site amplification for each frequency band and the V s20 (the average uppermost-20 m shear wave velocity) shows good correlation. A distance measurement called the asperity distance D Aspt is proposed to reasonably characterize the source-to-site distance for large earthquakes. Finally, the inversed site response is used to identify the soil nonlinearity in the main shock and aftershocks of Wenchuan earthquake. In ten of the 28 stations analyzed in the main shock, the soil behaved nonlinearly, where the ground motion level is apparently beyond a threshold of PGA > 300 cm/s2 or PGV > 20 cm/s, and only one station coded 51SFB has evidence of soil nonlinear behavior in the aftershocks.
Ren, Yefei; Wen, Ruizhi; Yamanaka, Hiroaki; Kashima, Toshihide
Surface Waves in Strong-Motion Records and their Importance for Engineering Applications
NASA Astrophysics Data System (ADS)
Strong motion records are composed by body as well as surface waves, however traditionally surface waves are considered of less engineering importance. Yet, surface waves generated within the sedimentary basin as a consequence of the interaction of incoming body waves with the heterogeneous basin structure could be a concern both in the near and the far-fields. The basin recorded ground-motion is distinct from the rocky site record. Typically, it has longer duration with long-period surface waves arriving at the later part of the seismogram. In order to properly explain the observation of surface waves in the basin records, we used a simple plane wave model propagating in a layered half-space medium. We considered basins with and without irregular boundary and seismic sources located both outside and beneath the basin. The multiple reflections and refractions within the basin due to the irregular basin structure is the primary cause for generating large-amplitude surface waves. Furthermore it appears that the source located outside the basin is more efficient in generating surface waves compared to the source beneath the basin. This feature is also supported by the observations during the earthquakes. In this communication, we used records from an aftershock of 1999 Chi-Chi earthquake to demonstrate the significance of surface waves in the strong motion records and we also explained a simplified yet powerful band-pass filtering approach to isolate the surface waves form the body waves. Later, we carried out a nonlinear dynamic analysis of steel framed structures ranging from 3 to 20 stories for both a basin record and the rocky site record. We noted that the long period surface waves have a significant contribution in the structural response especially for long-period structures (above 10 stories) and ignoring the surface waves in the structural design for structures located in the basin would heavily undermine the seismic risk.
Jetson Ronald, A.; Lai, C. G.; Papageoriou, A. S.
Preliminary analysis of strong-motion recordings from the 28 September 2004 Parkfield, California earthquake
The Parkfield 2004 earthquake yielded the most extensive set of strong-motion data in the near-source region of a magnitude 6 earthquake yet obtained. The recordings of acceleration and volumetric strain provide an unprecedented document of the near-source seismic radiation for a moderate earthquake. The spatial density of the measurements alon g the fault zone and in the linear arrays perpendicular to the fault is expected to provide an exceptional opportunity to develop improved models of the rupture process. The closely spaced measurements should help infer the temporal and spatial distribution of the rupture process at much higher resolution than previously possible. Preliminary analyses of the peak a cceleration data presented herein shows that the motions vary significantly along the rupture zone, from 0.13 g to more than 2.5 g, with a map of the values showing that the larger values are concentrated in three areas. Particle motions at the near-fault stations are consistent with bilateral rupture. Fault-normal pulses similar to those observed in recent strike-slip earthquakes are apparent at several of the stations. The attenuation of peak ground acceleration with distance is more rapid than that indicated by some standard relationships but adequately fits others. Evidence for directivity in the peak acceleration data is not strong. Several stations very near, or over, the rupturing fault recorded relatively low accelerations. These recordings may provide a quantitative basis to understand observations of low near-fault shaking damage that has been reported in other large strike-slip earthquak.
Shakal, A.; Graizer, V.; Huang, M.; Borcherdt, R.; Haddadi, H.; Lin, K. -W.; Stephens, C.; Roffers, P.
Earthquake Monitoring and Early Warning Systems in Taiwan (Invited)
NASA Astrophysics Data System (ADS)
The Taiwan region is characterized by a high shortening rate and a strong seismic activity. The Central Weather Bureau (CWB) is responsible for the earthquake monitoring in Taiwan. The CWB seismic network consists of 71 real-time short-period seismic stations in Taiwan region for routinely earthquake monitoring and has recorded about 18,000 events each year in a roughly 400 km x 550 km region. There are 53 real-time broadband stations install for seismological research purposes and reporting moment tensor solution in Taiwan. With the implementation of a real-time strong-motion network by the CWB, earthquake rapid reporting and early warning systems have been developed in Taiwan. The network consists of 110 stations. For rapid reporting system, when a potentially felt earthquake occurs around the Taiwan area, the location, magnitude and shake map of seismic intensities can be automatically reported within about 40 to 60 sec. For large earthquakes, the shaking map and losses can be estimated within 2 min after the earthquake occurrence. For earthquake early warning system, earthquake information could be determined at about 15 to 20 sec after a large earthquake occurrence. Therefore, this system can provide early warning before the arrival of S-wave for metropolitan areas located 70 km away from the epicenter. Recently, onsite earthquake early warning device is developed using MEMS sensor. It focuses on that to offer early warning for areas close to the epicenter.
Wu, Y.
Regional Characterization of the Crust in Metropolitan Areas for Prediction of Strong Ground Motion
NASA Astrophysics Data System (ADS)
Introduction: After the 1995 Kobe earthquake, the Japanese government increased its focus and funding of earthquake hazards evaluation, studies of man-made structures integrity, and emergency response planning in the major urban centers. A new agency, the Ministry of Education, Science, Sports and Culture (MEXT) has started a five-year program titled as Special Project for Earthquake Disaster Mitigation in Urban Areas (abbreviated to Dai-dai-toku in Japanese) since 2002. The project includes four programs: I. Regional characterization of the crust in metropolitan areas for prediction of strong ground motion. II. Significant improvement of seismic performance of structure. III. Advanced disaster management system. IV. Investigation of earthquake disaster mitigation research results. We will present the results from the first program conducted in 2002 and 2003. Regional Characterization of the Crust in Metropolitan Areas for Prediction of Strong Ground Motion: A long-term goal is to produce map of reliable estimations of strong ground motion. This requires accurate determination of ground motion response, which includes a source process, an effect of propagation path, and near surface response. The new five-year project was aimed to characterize the "source" and "propagation path" in the Kanto (Tokyo) region and Kinki (Osaka) region. The 1923 Kanto Earthquake is one of the important targets to be addressed in the project. The proximity of the Pacific and Philippine Sea subducting plates requires study of the relationship between earthquakes and regional tectonics. This project focuses on identification and geometry of: 1) Source faults, 2) Subducting plates and mega-thrust faults, 3) Crustal structure, 4) Seismogenic zone, 5) Sedimentary basins, 6) 3D velocity properties We have conducted a series of seismic reflection and refraction experiment in the Kanto region. In 2002 we have completed to deploy seismic profiling lines in the Boso peninsula (112 km) and the Sagami bay area (75 km) to image the subducting Philippine Sea plate. On the Boso line we drilled a hole at a depth of 2000 m with core sampling and logging including VSP. A high sensitivity down hole seismometer will bee installed at the hole. In 2003, a 71-km-long reflection/refraction line covered the Tokyo bay area to characterize the source area of the 1923 Kanto quake. The southern part of the line ran through the Miura peninsula, which was covered by a 20 x 15 km array consisting of 51 3-component continuously recording seismographs to identify the asperities suggested by strong motion studies. We also cover the eastern boundary of the Kanto Mountains in this fall. Reconstruction of source fault and velocity models allow for more realistic 3D seimic wave simulations. All of this information will be synthesized and provided to communities involved in probabilistic hazards analysis, risk assessment and societal response.
Hirata, N.; Sato, H.; Koketsu, K.; Umeda, Y.; Iwata, T.; Kasahara, K.
NetQuakes - A new approach to urban strong-motion seismology
NASA Astrophysics Data System (ADS)
There is a recognized need for more densely sampled strong ground motion recordings in urban areas to provide more accurate ShakeMaps for post-earthquake disaster assessment and to provide data for structural engineers to improve design standards. Ideally, the San Francisco Bay area would have a strong ground motion recorder every 1-2 km to adequately sample the region�s varied geology and built environment. This would require the addition of thousands of instruments to the existing network. There are several fiscal and logistical constraints that prevent us from doing this with traditional strong motion instrumentation and telemetry. In addition to the initial expense of instruments and their installation, there are the continuing costs of telemetry and maintenance. To address these issues, the USGS implemented the NetQuakes project to deploy small, relatively inexpensive seismographs for installation in 1-2 story homes and businesses that utilize the host�s existing Internet connection. The recorder has 18 bit resolution with �3g internal tri-axial MEMS accelerometers. Data is continuously recorded at 200 sps into a 1-2 week ringbuffer. When triggered, a miniSEED file is sent to USGS servers via the Internet. Data can also be recovered from the ringbuffer by a remote request through the servers. Following a power failure, the instrument can run for 36 hours using its internal battery. All client-server interactions are initiated by the instrument, so it safely resides behind a host�s firewall. Instrument and battery replacement can be performed by hosts to reduce maintenance costs. A connection to the host�s LAN, and thence to the public Internet, can be made using WiFi to minimize cabling. Although timing via a cable to an external GPS antenna is possible, it is simpler to use the Network Time Protocol (NTP) to synchronize the internal clock. NTP achieves timing accuracy generally better than a sample interval. Since February, 2009, we have installed more than 60 NetQuakes instruments in the San Francisco Bay Area and have successfully integrated their data into the near real time data stream of the Northern California Seismic System.
Luetgert, J. H.; Evans, J. R.; Hamilton, J.; Hutt, C. R.; Jensen, E. G.; Oppenheimer, D. H.
Calibration of strong motion models for Central America region and its use in seismic hazard assessment
NASA Astrophysics Data System (ADS)
We present the results of a study aimed at choosing the more suitable strong-motion models for seismic hazard analysis in the Central America (CA) Region. After a careful revision of the state of the art, different models developed for subduction and volcanic crustal zones, in tectonic environment similar to those of CA, were selected. These models were calibrated with accelerograms recorded in Costa Rica, Nicaragua and El Salvador. The peak ground acceleration PGA and Spectral Acceleration SA (T) derived from the records were compared with the ones predicted by the models in similar conditions of magnitude, distance and soil. The type of magnitude (Ms, Mb, MW), distance (Rhyp, Rrup, etc) and ground motion parameter (maximum horizontal component, geometrical mean, etc ) was taken into account in the comparison with the real data. As results of the analysis, the models which present a best fit with the local data were identified. These models have been applied for carrying out seismic hazard analysis in the region, in the frame of the RESIS II project financed by the Norwegian Foreign Department and also by the Spanish project SISMOCAES. The methodology followed is based on the direct comparison between PGA and SA 5 % damped response values extracted from actual records with the corresponding acceleration values predicted by the selected ground-motion models for similar magnitude, distance and soil conditions. Residuals between observed and predicted values for PGA, and SA (1sec) are calculated and plotted as a function of distance and magnitude, analyzing their deviation from the mean value. Besides and most important, a statistical analysis of the normalized residuals was carry out using the criteria proposed by Scherbaum et al. (2004), which consists in categorizing ground motion models based in a likelihood parameter that reflects the goodness-of-fit of the median values as well as the shape of the underlying distribution of ground motion residuals. Considering the results of the both analysis the conclusions can be drawn in the following paragraphs. Analyses of residuals show that in some cases the best adjustments of PGA and SA values do not always favor the same equation. Consequently, the following equations that present reasonable adjustments for both parameters are finally selected: Schmidt (2010) and Zhao et al (2006) for shallow crustal sources; Schmidt (2010), Zhao et al (2006), Youngs et al. (1997) and Lin & Lee (2008) for subduction interface and Schmidt (2010), Youngs et al (1997), Zhao et al (2006) and Garcia et al (2005) for inslab subduction sources. Finally, to improve the development of proper models of attenuation of the region, it is recommended to the governmental and private institutions, to support the implementation of permanent strong ground motion networks in all Central America countries, especially in Guatemala, Honduras, Nicaragua and Panama, including free field stations. In case of Costa Rica and El Salvador to strengthen the networks that already they operate.
Climent, A.; Benito, M. B.; Piedra, R.; Lindholm, C.; Gaspar-Escribano, J.
On the Effects of Non-Planar Fault Geometry on Strong Ground Motion
NASA Astrophysics Data System (ADS)
We quantify the effects of complex fault geometry on low-frequency (<1 Hz) strong ground motion using numerical modeling of dynamic rupture. Our tests include the computation of synthetic seismograms for several simple rupture scenarios with planar and curved fault approximations of the 1994 Northridge and the 1992 Landers earthquakes. We use the boundary integral equation method (BIEM) to compute the dynamic rupture process, which includes the normal stress effects along the curved fault geometries. The wave propagation and computation of synthetic seismograms are modeled using a fourth-order finite-difference method (FDM). The near-field ground motion is significantly affected by the acceleration, deceleration and arrest of rupture due to fault bending, as well as the the variation in directivity of the rupture. We compare 1-Hz near-fault peak velocities for 40o-dipping, thrust faults buried 5 km with dimensions 24 km by 16 km. Compared to that for a planar fault, such as most approximations of the Northridge earthquake, a 6-km-long hanging-wall or footwall splay with a maximum offset of 1 km can change peak velocities by up to a factor of 2-3 above the fault. This change is caused in part by a variation in directivity, in part by differences in the rupture dynamics for the scenarios. In particular, the curved faults cause a gradual arrest of rupture, while the planar fault rupture stops abruptly with a resulting increase in moment. Our tests suggest that the differences in waveform are larger on the hanging wall compared to those on the footwall. The results imply that kinematic ground motion estimates and slip inversion may be significantly biased by the omission of dynamic rupture effects and of relatively gentle variation in fault geometry, even for long-period waves.
Olsen, K. B.; Aochi, H.
City of Bing�l in May 2003: Assessment of strong ground motion records
NASA Astrophysics Data System (ADS)
The main shock of Bing�l earthquake ( M W = 6.4) recorded by six accelerometers in the area occurred at 03:27 local time on May 1, 2003. The largest acceleration value of north-south component was recorded as 545.5 cm/s2 at the nearest station which it is 12 km away from the epicenter of earthquake. Especially, 0.15 s short period was observed when high spectral acceleration value occurred. An acceleration value greater than 50 gal was recorded at the BNG (Bing�l) station and structural damage occurred within 6.5 s was very important for the near source and strong ground motion seismology. The recorded peak acceleration values were greater than the estimated empirical acceleration values. However, the structural damage was not as high and widespread as expected. This occurrence was explained by considering the factors of earthquake source, frequency content, effective duration, effective acceleration value, local soil conditions, rupture direction and attenuation.
�eken, U.; Beyhan, G.; Selim, H. H.
Relationship between strong-motion array parameters and the accuracy of source inversion and physical waves
We develop general rules for a strong-motion array layout on the basis of our method of applying a prediction analysis to a source inversion scheme. A systematic analysis is done to obtain a relationship between fault-array parameters and the accuracy of a source inversion. Our study of the effects of various physical waves indicates that surface waves at distant stations contribute significantly to the inversion accuracy for the inclined fault plane, whereas only far-field body waves at both small and large distances contribute to the inversion accuracy for the vertical fault, which produces more phase interference. These observations imply the adequacy of the half-space approximation used throughout our present study and suggest rules for actual array designs. -from Authors
Iida, M.; Miyatake, T.; Shimazaki, K.
Strong Motion Networks - Rapid Response and Early Warning Applications in Istanbul
NASA Astrophysics Data System (ADS)
In recent years several strong motion networks have been established in Istanbul with a preparation purpose for future probable earthquake. This study addresses the introduction of current seismic networks and presentation of some recent results recorded in these networks. Istanbul Earthquake Early Warning System Istanbul Earthquake Early Warning System has ten strong motion stations which were installed as close as possible to Marmara Sea main fault zone. Continuous on-line data from these stations via digital radio modem provide early warning for potentially disastrous earthquakes. Considering the complexity of fault rupture and the short fault distances involved, a simple and robust Early Warning algorithm, based on the exceedance of specified threshold time domain amplitude levels is implemented. The current algorithm compares the band-pass filtered accelerations and the cumulative absolute velocity (CAV) with specified threshold levels. Istanbul Earthquake Rapid Response System Istanbul Earthquake Rapid Response System has one hundred 18 bit-resolution strong motion accelerometers which were placed in quasi-free field locations (basement of small buildings) in the populated areas of the city, within an area of approximately 50x30km, to constitute a network that will enable early damage assessment and rapid response information after a damaging earthquake. Early response information is achieved through fast acquisition and analysis of processed data obtained from the network. The stations are routinely interrogated on regular basis by the main data center. After triggered by an earthquake, each station processes the streaming strong motion data to yield the spectral accelerations at specific periods and sends these parameters in the form of SMS messages at every 20s directly to the main data center through a designated GSM network and through a microwave system. A shake map and damage distribution map (using aggregate building inventories and fragility curves) will then be automatically generated using the algorithm developed for this purpose. Loss assessment studies are complemented by a large citywide digital database on the topography, geology, soil conditions, building, infrastructure and lifeline inventory. The shake and damage maps will be conveyed to the governor's and mayor's offices, fire, police and army headquarters within 3 minutes using radio modem and GPRS communication. Self Organizing Seismic Early Warning Information Network (SOSEWIN) in Atakoy District SOSEWIN sensors were developed by GFZ and Humbold University as part of SAFER project and EDIM project, and with cooperation of KOERI, the sensors were installed in Atakoy district of Istanbul city with Early Warning purpose. The main features of the SOSEWIN system are each sensing unit is comprised of low-cost components, undertakes its own seismological data processing, analysis and archiving, and its self-organizing capability with wireless mesh network communication. Seismic Network in Important Structures Some of the critical structures located in Istanbul city such as Fatih Sultan Mehmet Suspension Bridge which is connecting Asian and European sides of the city, Hagia Sophia Museum and Suleymaniye Mosque which are historical structures with an age of over 1000 years and 450 years respectively, and Isbank Tower which is one of the tallest structures in the city with a height of 181.2m are monitorized to observe their seismic behavior.
Zulfikar, C.; Alcik, H.; Ozel, O.; Erdik, M.
Attenuation Tomography Based on Strong Motion Data: Case Study of Central Honshu Region, Japan
NASA Astrophysics Data System (ADS)
Three-dimensional frequency dependent S-wave quality factor (Q?(f)) value for the central Honshu region of Japan has been determined in this paper using an algorithm based on inversion of strong motion data. The method of inversion for determination of three-dimensional attenuation coefficients is proposed by H ashida and S himazaki (J Phys Earth. 32, 299-316, 1984) and has been used and modified by J oshi (Curr Sci. 90, 581-585, 2006; Nat Hazards. 43, 129-146, 2007) and J oshi et al. (J. Seismol. 14, 247-272, 2010). Twenty-one earthquakes digitally recorded on strong motion stations of Kik-net network have been used in this work. The magnitude of these earthquake ranges from 3.1 to 4.2 and depth ranging from 5 to 20 km, respectively. The borehole data having high signal to noise ratio and minimum site effect is used in the present work. The attenuation structure is determined by dividing the entire area into twenty-five three-dimensional blocks of uniform thickness having different frequency-dependent shear wave quality factor. Shear wave quality factor values have been determined at frequencies of 2.5, 7.0 and 10 Hz from record in a rectangular grid defined by 35.4�N to 36.4�N and 137.2�E to 138.2�E. The obtained attenuation structure is compared with the available geological features in the region and comparison shows that the obtained structure is capable of resolving important tectonic features present in the area. The proposed attenuation structure is compared with the probabilistic seismic hazard map of the region and shows that it bears some remarkable similarity in the patterns seen in seismic hazard map.
Kumar, Parveen; Joshi, A.; Verma, O. P.
Simulation of strong ground motion for moderate earthquakes: comparison between two high frequency approaches
NASA Astrophysics Data System (ADS)
We used two different strong ground motion simulation techniques to generate shaking scenarios for the 1997 Colfiorito earthquake (Mw=6.0). This earthquake has been studied in the framework of a Italian research project (supported by Gruppo Nazionale per la Difesa dai Terremoti - INGV, 2002-2003). The project concerns the design of ground shaking scenarios based on the identification of the position, geometry and rupture mechanism of seismogenetic faults and on the characterization of the crustal structure. Both techniques use the high frequency solution (ray theory) to compute the Green functions in a flat-layered velocity model. While one method (ASymptotic Method, ASM) solves numerically the representation integral, the other one (Deterministic-Stochastic Method, DSM) generalizes the point-source stochastic method using a deterministic acceleration envelope for an extended fault. Only the direct S wave field is computed because, in the near source range, it can be considered dominant in amplitude with respect to the P wave field and secondary phases. We computed synthetic time histories at 64 nodes of a grid area (60km x 60km) up to fmax=5 Hz. First of all, we compared the methods for two source models obtained, for the Colfioririto earthquake, by the inversion of geodetic and accelerometric data. Both techniques give similar distribution of PGA and integral ground motion parameters. In particular, peak values are not symmetrically distributed around the fault, but show the largest amplitude values north to the Colfiorito fault, in the directive direction. The reliability of the proposed rupture scenario has been checked for 6 accelerometric stations located at epicentral distances ranging from 5 to 30 Km that recorded the mainshock. We then generated shaking scenarios varying several parameters, such as the nucleation position, the slip distribution and the rupture velocity. Fault geometry, source mechanism and propagation medium are fixed. The results of the simulations have been grouped in three families, on the base of the position of the nucleation point (on the left side, in the middle and on the right side of the fault) to emphasise directivity effects associated to the rupture propagation along an extended fault. For each family of rupture scenarios, a statistical analysis was performed to evaluate the variability of strong ground motion parameters.
Emolo, A.; Pacor, F.; Cultrera, G.; Franceschina, G.; Zollo, A.; Cocco, M.
Shallow velocity structure and Poisson's ratio at the Tarzana, California, strong-motion accelerometer site
The 17 January 1994, Northridge, California, earthquake produced strong ground shaking at the Cedar Hills Nursery (referred to here as the Tarzana site) within the city of Tarzana, California, approximately 6 km from the epicenter of the mainshock. Although the Tarzana site is on a hill and is a rock site, accelerations of approximately 1.78 g horizontally and 1.2 g vertically at the Tarzana site are among the highest ever instrumentally recorded for an earthquake. To investigate possible site effects at the Tarzana site, we used explosive-source seismic refraction data to determine the shallow (<70 m) P- and S-wave velocity structure. Our seismic velocity models for the Tarzana site indicate that the local velocity structure may have contributed significantly to the observed shaking. P-wave velocities range from 0.9 to 1.65 km/sec, and S-wave velocities range from 0.20 and 0.6 km/sec for the upper 70 m. We also found evidence for a local S-wave low-velocity zone (LVZ) beneath the top of the hill. The LVZ underlies a CDMG strong-motion recording site at depths between 25 and 60 m below ground surface (BGS). Our velocity model is consistent with the near-surface (<30 m) P- and S-wave velocities and Poisson's ratios measured in a nearby (<30 m) borehole. High Poisson's ratios (0.477 to 0.494) and S-wave attenuation within the LVZ suggest that the LVZ may be composed of highly saturated shales of the Modelo Formation. Because the lateral dimensions of the LVZ approximately correspond to the areas of strongest shaking, we suggest that the highly saturated zone may have contributed to localized strong shaking. Rock sites are generally considered to be ideal locations for site response in urban areas; however, localized, highly saturated rock sites may be a hazard in urban areas that requires further investigation.
Catchings, R. D.; Lee, W. H. K.
Cooperative Particle Motions and Dynamical Behaviors of Free Dislocations in Strongly Coupled Quasi-2D Dusty Plasmas
We report the optical study of microscopic particle motions and the dynamical behavior of free dislocations (FDs) in the strongly coupled quasi-two-dimensional dusty plasmas with SiO{sub 2} fine particle suspensions. The continuous excitation and relaxation of rotational cooperative particle motions with varying scales and lifetimes are observed, which distort the lattice and induce the FD processes such as generation, dissociation, propagation, recombination, and annihilation under the conservation of Burgers vector. {copyright} {ital 1996 The American Physical Society.}
Chiang, C.; I, L. [Department of Physics, National Central University, Chungli, Taiwan 32054, Republic of (China)] [Department of Physics, National Central University, Chungli, Taiwan 32054, Republic of (China)
Long-Period Strong Ground Motions Having Fired Large Oil Storage Tanks During the 2003 Tokachi-Oki, Japan, Earthquake
The 2003 Tokachi-oki, Japan, earthquake (Mw8.0; Japan Meteorological Agency, 2003) generated large-amplitude long-period (5 to 8 sec) strong ground motions in the Yufutsu plain, Hokkaido, Japan that is about 200 km away from the epicenter. Those motions excited big sloshing in many large oil storage tanks located on the plain and the sloshing caused two tank fires and several floating
K. Hatayama
Seismic Hazard Mapping and Microzonation in the Sikkim Himalaya through GIS Integration of Site Effects and Strong Ground Motion Attributes
The seismic ground motion hazard is mapped in the Sikkim Himalaya with local and regional site conditions incorporated through geographic information system. A strong motion network in Sikkim comprising of 9 digital accelerographs recorded more than 100 events during 1998�2002, of which 41 events are selected with signal-to-noise ratio =3 for the estimation of site response (SR), peak ground acceleration
Sankar Kumar Nath
Source Rupture Process of the 2007 Noto Hanto Earthquake, Japan, Obtained from Strong Ground Motion and GPS Data
NASA Astrophysics Data System (ADS)
The 2007 Noto Hanto earthquake (MJMA 6.9) occurred near the west coast of the Noto peninsula, central Japan, on March 25, 2007. This is an inland crustal earthquake having oblique slip source mechanism. The strong ground motions from this event brought severe damages on wooden houses in and around near-source region (e.g., Wajima city and Anamizu town). Near-source strong motion records have great potential to investigate detailed source rupture process in space and time. However, strong ground motions are generally affected by amplifications due to the subsurface structure under the station. It is quite important for obtaining a reliable source model to use appropriate velocity structure models. We have employed an approach in which each strong motion station has its identical velocity structure model. Here, one-dimensional velocity structure model for each strong motion station is constructed after an optimization procedure using the aftershock's waveform data. Firstly, a reference velocity structure model is assumed by referring to the refraction survey using controlled sources by Aoki et al. (1972) and microtremor array measurements by Kanno et al. (2003). This reference velocity structure model consists of three sedimentary layers on the seismic bedrock. Then, the thickness of each sedimentary layer for each station is estimated to fit the observed waveforms of the aftershock by using the Genetic Algorithm. Twelve strong motion stations of K-NET (Kinoshita, 1997) and KiK-net (Aoi et al., 2000) are employed in this study. We succeeded to get a reasonable velocity structure model for each station to give a good fit of the main S-wave part in the observation. The kinematic source rupture process of the 2007 Noto Hanto earthquake is estimated by the linear waveform inversion using multiple time windows (Hartzell and Heaton, 1983). The spatiotemporal smoothing constraints to stabilize the solution are introduced following Sekiguchi et al. (2000). The velocity waveform data in 0.05-1 Hz at 12 strong motion stations are used. The static GPS-measured displacement data at 18 GEONET stations (Miyazaki et al., 1997) are also included in the data set. Static displacement at each station is calculated from the daily coordinate solutions released from GEONET. By including GPS data, we can get a broadband source model in this analysis. The obtained source model shows that large slip is observed in shallow portion of the fault plane near the hypocenter and the spatial slip distribution seems rather simple. This model reproduces both of the strong motion and GPS data fairly well. But, we might need to adjust the geometry of the fault plane to get better fitting of the GPS-measured displacement data. The difference between the source model from strong motion and GPS data and that from strong motion only is not significant. We could get a robust source model using only strong motion data with well-calibrated Green's functions for strong motion data. Finally, in order to evaluate effectiveness of our approach, we will compare the result obtained by the station- dependent velocity structure models with the one obtained from a uniform velocity structure model.
Asano, K.; Iwata, T.
Shallow shear wave velocity and Q structures at the El Centro strong motion accelerograph array
NASA Astrophysics Data System (ADS)
At three sites in the U.S. Geological Survey El Centro Strong Motion Accelerograph Array (EO5, EO6 and EO7), we have used the dispersive and attenuative properties of artificially generated Rayleigh waves to infer the depth dependence of shear wave velocity (?) and quality factor (Q) and a site dependent equivalent elastic source spectrum. This approach provides an inexpensive means for determining two important quantities (? and Q) required to estimate the response of sites to earthquakes. We find that the shear velocities and the gradients in shear velocities down to depths of 100 meters at station EO6 (in the wedge between the Imperial and Brawley faults) are nearly twice those at either station EO5 and EO7 (east and west, respectively, of the wedge). Also, the seismogram character, surface wave dispersion and shear wave velocity structure at stations EO5 and EO7 are similar to each other while they are different from EO6. These results show significant structural differences between the wedge beneath EO6 and surrounding areas. The anomalously high accelerations recorded at EO6 during the 1979 Imperial Valley earthquake may be related to these differences.
Barker, Terrance G.; Stevens, Jeffry L.
An evaluation of the strong ground motion recorded during the May 1, 2003 Bingo??l Turkey, earthquake
An important record of ground motion from a M6.4 earthquake occurring on May 1, 2003, at epicentral and fault distances of about 12 and 9km, respectively, was obtained at a station near the city of Bingo??l, Turkey. The maximum peak ground values of 0.55 g and 36 cm/s are among the largest ground-motion amplitudes recorded in Turkey. From simulations and comparisons with ground motions from other earthquakes of comparable magnitude, we conclude that the ground motion over a range of frequencies is unusually high. Site response may be responsible for the elevated ground motion, as suggested from analysis of numerous aftershock recordings from the same station. The mainshock motions have some interesting seismological features, including ramps between the P-and S-wave that are probably due to near- and intermediate-field elastic motions and strong polarisation oriented at about 39 degrees to the fault (and therefore not in the fault-normal direction). Simulations of motions from an extended rupture explain these features. The N10E component shows a high-amplitude spectral acceleration at a period of 0.15 seconds resulting in a site specific design spectrum that significantly overestimates the actual strength and displacement demands of the record. The pulse signal in the N10E component affects the inelastic spectral displacement and increases the inelastic displacement demand with respect to elastic demand for very long periods. ?? Imperial College Press.
Akkar, S.; Boore, D. M.; Gulkan, P.
Lotung large-scale seismic test strong motion records. Volume 1, General description: Final report
The Electric Power Research Institute (EPRI), in cooperation with the Taiwan Power Company (TPC), constructed two models (1/4 scale and 1/12 scale) of a nuclear plant concrete containment structure at a seismically active site in Lotung, Taiwan. Extensive instrumentation was deployed to record both structural and ground responses during earthquakes. The experiment, generally referred to as the Lotung Large-Scale Seismic Test (LSST), was used to gather data for soil-structure interaction (SSI) analysis method evaluation and validation as well as for site ground response investigation. A number of earthquakes having local magnitudes ranging from 4.5 to 7.0 have been recorded at the LSST site since the completion of the test facility in September 1985. This report documents the earthquake data, both raw and processed, collected from the LSST experiment. Volume 1 of the report provides general information on site location, instrument types and layout, data acquisition and processing, and data file organization. The recorded data are described chronologically in subsequent volumes of the report.
Not Available
Three Dimensional Simulations of Strong Motions for Great Earthquakes on the Cascadia Subduction Zone
NASA Astrophysics Data System (ADS)
Using a finite-fault rupture model, we ran a finite difference code to simulate a variety of Mw 8 and larger events on the Cascadia subduction zone using a 3D regional velocity model and two different 3D velocity models for the Seattle basin. Our results reveal the magnitude and duration of shaking that should be expected in the built environment for a megathrust event with a rupture length less than the entire length of the subduction zone. In the next step we will consider events that rupture the entire length of the subduction zone, similar in scope to the 1700 event, and compare our results to those considered for the national seismic hazard maps. In order to make predictions on the strength and duration of shaking in Cascadia due to a large megathrust event, we developed a kinematic fault rupture model based on a k-2 decay in final slip spectrum that has a scale-dependent rise time. This produces a ?-2 decay in the radiated displacement spectrum above the corner frequency, which is then modified by rupture directivity. In order to produce a k-2 decay in the final slip spectrum, we modeled the final slip as the sum of asperities with various wave numbers produced by calculating normal modes for a membrane, then shifting the phase of the standing waves to randomize the pattern. In this way, slip naturally decays towards the edges of the rupture without having to use a taper, we can produce a final slip model with any spectrum we choose, and each wave number can be assigned a unique rise time. The slip on each individual asperity initiates in time according to its closest distance to the hypocenter and the rupture velocity. The Cascadia subduction zone off the coast of northwestern United States and southwestern Canada is capable of producing megathrust earthquakes with magnitudes up to Mw 9.0 for margin-wide events and magnitudes greater than Mw 8.0 if only part of the subduction zone ruptures. The average recurrence interval for margin-wide megathrust earthquakes on the Cascadia subduction zone is about 500 years and the last margin-wide event occurred in 1700. The estimate of the recurrence interval for events that rupture only part of the subduction zone is more controversial, but the recurrence time is thought to be somewhere around 300 years. If a large event were to occur today, the cities of Portland, Oregon, Seattle, Washington, and Vancouver, British Columbia and other inhabited areas in the forearc basin and on the coast would be subjected to strong and long duration shaking and coastal areas would likely be subjected to a tsunami. Observations from the Maule, Chile and Tohoku-Oki, Japan earthquakes will be used to guide the specification of rupture time histories for the Cascadia 3D simulations. We are particularly interested in producing realistic ground motions at periods of 2 to 6 s that affect high-rise buildings. The amplitude and duration of these motions are strongly affected by the rise time of slip on the fault, the coherence of rupture propagation, and the presence of deep sedimentary basins such as the Seattle and Tacoma basins.
Delorey, A. A.; Frankel, A. D.; Stephenson, W. J.; Liu, P.
Observations and stochastic modelling of strong ground motions for the 2011 October 23 Mw 7.1 Van, Turkey, earthquake
NASA Astrophysics Data System (ADS)
The 2011 October 23 Van earthquake occurred at 13:41 local time in Eastern Turkey with an epicentre at 43.36oE, 38.76oN (Kandilli Observatory Earthquake Research Institute (KOERI)), 16 km north-northeast of the city of Van, killing around 604 people and leaving thousands homeless. This work presents an overview of the main features of the seismic ground shaking during the Van earthquake. We analyse the ground motion characteristics of the mainshock in terms of peak ground acceleration (PGA), peak ground velocity (PGV) and spectral accelerations (SA, 5 per cent of critical damping). In order to understand the characteristics of the ground motions induced by the mainshock, we also study the site response of the strong motion stations that recorded the seismic sequence. The lack of seismic recordings in this area imposes major constraints on the computation of reliable seismic hazard estimates for sites in this part of the country. Towards this aim, we have used a stochastic method to generate high frequency ground motion synthetics for the Mw 7.1 Van 2011 earthquake. The source mechanism of the Van event and regional wave propagation parameters are constrained from the available and previous studies. The selected model parameters are then validated against recordings. We also computed the residuals for the ground motion parameters in terms of PGA and PGV at each station and the model parameter bias by averaging the residuals over all the stations. The attenuation of the simulated ground motion parameters is compared with recent global and regional ground motion prediction equations. Finally, since it has been debated whether the earthquake of November 9 was an aftershock of the October 23 earthquake, we examine whether static variation of Coulomb stress could contribute to the observed aftershock triggering during the 2011 Van Lake sequence. Comparison with empirical ground motion prediction illustrated that the observed PGA data decay faster than the global empirical ground motion equations, both at moderate and larger distance; this feature is captured by the AC10 model that is derived from Turkish earthquake database. Faster attenuation of ground motion due to the high attenuation of seismic waves in the Eastern Anatolian plateau is in agreement with our stochastic simulations of strong ground motions of the 2011 October 23 Van earthquake. This highlights the importance of retrieving specific regional seismic parameters for the ground motion predictive equations. The stress redistribution computation indicates that the October sequence had an active role in promoting the November aftershocks, being the Coulomb stress variation positive in the entire region of interest. Furthermore, the Van events enhanced the stress level on the Caldiran fault.
Akinci, Aybige; Antonioli, Andrea
Modelling of Strong Ground Motions from 1991 Uttarkashi, India, Earthquake Using a Hybrid Technique
NASA Astrophysics Data System (ADS)
We present a simple and efficient hybrid technique for simulating earthquake strong ground motion. This procedure is the combination of the techniques of envelope function (M idorikawa et al. Tectonophysics 218:287-295, 1993) and composite source model (Z eng et al. Geophys Res Lett 21:725-728, 1994). The first step of the technique is based on the construction of the envelope function of the large earthquake by superposition of envelope functions for smaller earthquakes. The smaller earthquakes (sub-events) of varying sizes are distributed randomly, instead of uniform distribution of same size sub-events, on the fault plane. The accelerogram of large event is then obtained by combining the envelope function with a band-limited white noise. The low-cut frequency of the band-limited white noise is chosen to correspond to the corner frequency for the target earthquake magnitude and the high-cut to the Boore's f max or a desired frequency for the simulation. Below the low-cut frequency, the fall-off slope is 2 in accordance with the ?2 earthquake source model. The technique requires the parameters such as fault area, orientation of the fault, hypocenter, size of the sub-events, stress drop, rupture velocity, duration, source-site distance and attenuation parameter. The fidelity of the technique has been demonstrated by successful modeling of the 1991 Uttarkashi, Himalaya earthquake (Ms 7). The acceptable locations of the sub-events on the fault plane have been determined using a genetic algorithm. The main characteristics of the simulated accelerograms, comprised of the duration of strong ground shaking, peak ground acceleration and Fourier and response spectra, are, in general, in good agreement with those observed at most of the sites. At some of the sites the simulated accelerograms differ from observed ones by a factor of 2-3. The local site geology and topography may cause such a difference, as these effects have not been considered in the present technique. The advantage of the technique lies in the fact that detailed parameters such as velocity-Q structures and empirical Green's functions are not required or the records of the actual time history from the past earthquakes are not available. This method may find its application in preparing a wide range of scenarios based on simulation. This provides information that is complementary to the information available in probabilistic hazard maps.
Kumar, Dinesh; Teotia, S. S.; Sriram, V.
Rupture process of the 2009 L'Aquila, Italy, earthquake inferred from inversions of teleseismic and strong motion datasets
NASA Astrophysics Data System (ADS)
The L'Aquila, Central Italy earthquake, occurred on April 6, 2009 at 01:32:40 UTC time. This Mw 6.3 (Global CMT) event caused large damages to the city of L'Aquila and surrounding villages of the Abruzzi region. A detailed study of the source process of this event is essential in understanding the observed macrosesmic effects and the relation between the causative fault and the aftershock activity. The use of the seismological datasets recorded at different distance range is expected to give supplementary information on the rupture process offering a more stable and detailed image of the source area, while each of the teleseismic and strong motion data carries information on different period ranges of the process at the source. In this study we developed a rupture model for the L'Aquila event by analyzing the teleseismic waveform data of IRIS-DMC and near-field strong motion records from the Italian Strong Motion Network (RAN). We also examined what details of the rupture history can be deduced from the teleseismic data alone, the strong motion data alone, and the combined teleseismic and strong motion data sets. At first, we estimated the general pattern of the source rupture area and determined the hypocentral depth, by performing the moment tensor analysis as well as the source inversion of broadband teleseismic records using the methods developed by Kikuchi and Kanamori (1982, 1991), Kikuchi et al. (2003) and Yoshida et al. (1996). Based on the aftershock study (Chiarabba et al., 2009) we assumed that the rupture occurred on the SW dipping fault plane with the dimensions of 25 km in length by 15 km in width. We also assumed strike = 148 deg. and dip = 44 deg., based on the residuals of the point source analysis and the aftershock distribution. The optimal depth that maximizes the waveform fit was found to be 6 km. The total seismic moment corresponds to Mo = 3.10 x 10**18 Nm. The inverted slip model shows one main asperity located in the upper shallow part of the fault close to the hypocenter, and a rupture extension towards the southeast. We further performed a waveform inversion of near-field strong motion data from ITACA database using the method of Yoshida et al. (1996) and fault parameters from the teleseismic waveform inversion. We used three component velocity records from the stations located within the distance of 55 km from the epicenter. The velocity structure for each of the stations is approximated by a 1D model adjusted by the forward modeling of the aftershocks records available from the ITACA database. The slip distribution of our best model shows a major asperity located about 18 km SE from the hypocenter. The total seismic moment corresponds to Mo = 3.5610 x 10**18 Nm and the optimal depth is found to be 8 km. We also determined the average rupture velocity that minimizes the residuals between observed and synthetic waveforms to be 1.9 km/s. The resulted source model, location of the main asperity, in generally agrees well with the studies by other authors (Cirella et al., 2009, Atzori et al., 2009). However, the slip distributions obtained from the inversion of the teleseismic and the strong motion datasets are largely different. We further investigated the possible explanation of this difference by performing the forward modeling of the teleseismic data using the source model from the strong motion inversion and the joint inversion of the teleseismic and the strong motion datasets. The results of these analysis as well as the details on the origin of the differences in the teleseismic and strong motion models will be presented in the meeting.
Poiata, Natalia; Koketsu, Kazuki; Vuan, Alessandro; Miyake, Hiroe
Long-Period Strong Ground Motions Having Fired Large Oil Storage Tanks During the 2003 Tokachi-Oki, Japan, Earthquake
NASA Astrophysics Data System (ADS)
The 2003 Tokachi-oki, Japan, earthquake (Mw8.0; Japan Meteorological Agency, 2003) generated large-amplitude long-period (5 to 8 sec) strong ground motions in the Yufutsu plain, Hokkaido, Japan that is about 200 km away from the epicenter. Those motions excited big sloshing in many large oil storage tanks located on the plain and the sloshing caused two tank fires and several floating roofs to sink. Japanese nation-wide strong-motion observation networks have provided us with the first data set consisting of densely sampled strong ground motions that are rich in long-period components. This data set clearly showed that the large long-period motions were not observed before the waves entering the plain, i.e. the Yufutsu plain grew the long-period ground motions (Koketsu et al., 2005). The high density of spatial sampling can also show the spatial distribution of strength of long-period motions in the plain and their propagation there. We show by some contour maps of velocity responses that the strongest long-period shaking in the Yufutsu plain was observed around the downtown area of the Tomakomai city where the damage to oil tanks was more severe than any other areas. The isochrone of peaks of envelopes suggests a possibility that the long-period wave trains were focusing into the downtown from different directions. In order to study the excitation and the propagation process of long-period motions in the Yufutsu plain, an attempt was made to explore its deep sediment-bedrock structure by means of long-period microtremor array observations (Kanno et al., 2005). Relying on their resultant S-wave velocity profiles, we try to reproduce the features of the long-period motions observed there during the 2003 Tokachi-oki earthquake by making numerical simulations of 2-D seismic wave-fields by means of the finite difference method. To date we have succeeded in reproducing qualitatively the observed phenomena that the amplitude of long-period motions in the downtown area of the Tomakomai city was larger than any other areas in the Yufutsu plain.
Hatayama, K.
Ground motion and rupture process of the 2004 Mid Niigata Prefecture earthquake obtained from strong motion data of K-NET and KiK-net
The 2004 Mid Niigata Prefecture earthquake (37.289�N, 138.870�E, 13.1 km, MJMA 6.8; JMA), also known as the 2004 Niigata Prefecture Chuetsu earthquake, was a thrust type earthquake that occurred on October 23, 2004 at 17:56 (JST). Strong ground motions of PGA 800-1700 cm\\/s2 and PGV 60-130 cm\\/s were observed at stations located immediately above the source region. We deduced the
R. Honda; S. Aoi; N. Morikawa; H. Sekiguchi; T. Kunugi; H. Fujiwara
Strong Motion Simulation of the Niigata-ken Chuetsu-oki Earthquake (2007), Japan
NASA Astrophysics Data System (ADS)
On July 16th, 2007, the Niigata-ken Chuetsu-oki Earthquake (M6.8) occurred off Niigata Prefecture in Japan, claiming 68 casualties and more than 4,000 injured. The heavily damaged areas were Kariwa Village and Kashiwazaki City of Niigata Prefecture, and a fire broke out in an electrical transformer at the Kashiwazaki-Kariwa Nuclear Power Plant (KKNPP). Regarding this earthquake, the several source models have been proposed. Based on the dimensions of the proposed source models, we simulate strong motion in the epicentral area including the KKNPP site by using the fourth order 3-D finite-difference method with staggered-discontinuous-grids, that is, GMS code (Aoi.S and H. Fujiwara, 1999). First, we try to modify the 3-D subsurface structure model of Niigata Prefecture, developed and provided by JNES (Japan Nuclear Energy Safety Organization). To calibrate this model, we simulate three aftershocks recordings at KKNPP, assuming point sources with the source mechanisms provided by F-net. The shapes of the main portion of the velocity waveform are well reproduced in general. However, regarding the time differences between P-wave and S-wave (i.e., S-P time), the results do not show good match between observed data and calculations. In order to correct the difference in S-P time, we set a horizontal boundary at the depth of 12.5km in the bedrock and assigned different velocity structures for the shallow and deep part of the bedrock. As a result, we can match S-P time of the shallow aftershock. Next, we simulate the main shock recordings using the modified subsurface structure described above. Since the observed data of the main shock shows three distinctive velocity pulses, the initial model that we adopt consists of a three asperities source model from the previous study of Kawabe and Kamae (2008). The following is our calculation procedure. First, the shapes of slip velocity time functions are assumed to be a simple triangle. Then, simulated time histories are convolved with the shapes of the assumed slip velocity time function for each asperity. Finally, time histories of each asperity are overlapped considering the time delay between ruptures. As a result, by multiplying the seismic moment of two asperities (Asperity 1 and 3) by 1.5 and searching appropriate shapes of the slip velocity functions for three asperities, we can reproduce the observation recordings at KKNPP. However, large amplitude of the third velocity pulse in EW component cannot be reproduced. By plotting the particle motions of velocity time histories, we confirm that the third pulse with large amplitude at station KK1 appears in a different direction from the predominant direction seen in the calculated velocities. We will include the other observed sites to our targets and modify the shape of slip velocity time functions. We will also investigate the cause of conspicuous velocity pulse dominantly in the EW component, scrutinizing either from the local subsurface structure or the source process complexity.
Nitta, Y.; Matsushima, S.; Kawase, H.
Family-based association testing strongly implicates DRD2 as a risk gene for schizophrenia in Han Chinese from Taiwan
The gene that codes for dopamine receptor D2 (DRD2 on chromosome 11q23) has long been a prime functional and positional candidate risk gene for schizophrenia. Collectively, prior case�control studies found a reliable effect of the Ser311Cys DRD2 polymorphism (rs1801028) on risk for schizophrenia, but few other polymorphisms in the gene had ever been evaluated and no adequately powered family-based association study has been performed to date. Our objective was to test 21 haplotype-tagging and all three known nonsynonymous single-nucleotide polymorphisms (SNPs) in DRD2 for association with schizophrenia in a family-based study of 2408 Han Chinese, including 1214 affected individuals from 616 families. We did not find a significant effect of rs1801028, but we did find significant evidence for association of schizophrenia with two multi-marker haplotypes spanning blocks of strong linkage disequilibrium (LD) and nine individual SNPs (Ps < 0.05). Importantly, two SNPs (rs1079727 and rs2283265) and both multi-marker haplotypes spanning entire LD blocks (including one that contained rs1801028) remained significant after correcting for multiple testing. These results further add to the body of data implicating DRD2 as a schizophrenia risk gene; however, a causal variant(s) in DRD2 remains to be elucidated by further fine mapping of the gene, with particular attention given to the area surrounding the third through fifth exons.
Glatt, SJ; Faraone, SV; Lasky-Su, JA; Kanazawa, T; Hwu, H-G; Tsuang, MT
Estimation of Strong Ground Motions for 2001 Bhuj ( M w 7.6), India Earthquake
NASA Astrophysics Data System (ADS)
The strong ground motions for the 2001 Bhuj ( M w 7.6) India earthquake have been estimated on hard rock and B/C boundary (NEHRP) levels using a recently modified version of stochastic finite fault modeling based on dynamic corner frequency (M otazedian and A tkinson in Bull Seismol Soc Am 95, 995-1010 2005). Incorporation of dynamic corner frequency removes the limitations of earlier stochastic methods. Simulations were carried out at 13 sites in Gujarat where structural response recorder (SRR) recordings are available. In addition, accelerograms were simulated at the B/C boundary at a large number of points distributed on a grid. The corresponding response spectra have also been estimated. The values of peak ground accelerations and spectral accelerations at three periods (0.4, 0.75 and 1.25 s) are presented in the form of contour maps. The maximum value of peak ground acceleration (PGA) in the center of meizoseismal zone is 550 cm/s2. The response spectral acceleration in same zone is 900 cm/s2 ( T = 0.4 s), 600 cm/s2 ( T = 0.75 s) and 300 cm/s2 ( T = 1.25 s). The innermost PGA contour is on the fault plane. A comparison of the PGA values obtained at 13 sites in this study with those obtained in earlier studies on the same sites, but employing different methods, show that the present PGA values are comparable at most of the sites. The rate of decay of PGA values is fast at short distances as compared to that at longer distances. The PGA values obtained here put some constraints on the expected values from a similar earthquake in the region. A synthetic intensity map has been prepared from the estimated values of PGA using an empirical relation. A comparison with the reported intensity map of the earthquake shows the synthetic MMI values, as expected, are lower by 1 unit compared to reported intensity map. The contour map of PGA along with the contour maps of spectral acceleration at various periods permit the assessment of damage potential to various categories of houses and other structures. Such information will be quite important in planning of mitigation and disaster management programs in the region.
Chopra, Sumer; Kumar, Dinesh; Rastogi, Bal Krishna
Ground Motion Simulation for a Large Active Fault System using Empirical Green's Function Method and the Strong Motion Prediction Recipe - a Case Study of the Noubi Fault Zone -
NASA Astrophysics Data System (ADS)
The 1995 Hyogo-ken Nambu Earthquake (1995) near Kobe, Japan, spurred research on strong motion prediction. To mitigate damage caused by large earthquakes, a highly precise method of predicting future strong motion waveforms is required. In this study, we applied empirical Green's function method to forward modeling in order to simulate strong ground motion in the Noubi Fault zone and examine issues related to strong motion prediction for large faults. Source models for the scenario earthquakes were constructed using the recipe of strong motion prediction (Irikura and Miyake, 2001; Irikura et al., 2003). To calculate the asperity area ratio of a large fault zone, the results of a scaling model, a scaling model with 22% asperity by area, and a cascade model were compared, and several rupture points and segmentation parameters were examined for certain cases. A small earthquake (Mw: 4.6) that occurred in northern Fukui Prefecture in 2004 were examined as empirical Green's function, and the source spectrum of this small event was found to agree with the omega-square scaling law. The Nukumi, Neodani, and Umehara segments of the 1891 Noubi Earthquake were targeted in the present study. The positions of the asperity area and rupture starting points were based on the horizontal displacement distributions reported by Matsuda (1974) and the fault branching pattern and rupture direction model proposed by Nakata and Goto (1998). Asymmetry in the damage maps for the Noubi Earthquake was then examined. We compared the maximum horizontal velocities for each case that had a different rupture starting point. In the case, rupture started at the center of the Nukumi Fault, while in another case, rupture started on the southeastern edge of the Umehara Fault; the scaling model showed an approximately 2.1-fold difference between these cases at observation point FKI005 of K-Net. This difference is considered to relate to the directivity effect associated with the direction of rupture propagation. Moreover, it was clarified that the horizontal velocities by assuming the cascade model was underestimated more than one standard deviation of empirical relation by Si and Midorikawa (1999). The scaling and cascade models showed an approximately 6.4-fold difference for the case, in which the rupture started along the southeastern edge of the Umehara Fault at observation point GIF020. This difference is significantly large in comparison with the effect of different rupture starting points, and shows that it is important to base scenario earthquake assumptions on active fault datasets before establishing the source characterization model. The distribution map of seismic intensity for the 1891 Noubi Earthquake also suggests that the synthetic waveforms in the southeastern Noubi Fault zone may be underestimated. Our results indicate that outer fault parameters (e.g., earthquake moment) related to the construction of scenario earthquakes influence strong motion prediction, rather than inner fault parameters such as the rupture starting point. Based on these methods, we will predict strong motion for approximately 140 to 150 km of the Itoigawa-Shizuoka Tectonic Line.
Kuriyama, M.; Kumamoto, T.; Fujita, M.
Extracting the Building Response with QCN-Taiwan Sensor Data: Application to the building of Science Education Center, National Taiwan Normal University
NASA Astrophysics Data System (ADS)
We have taken advantage of strong motion sensor data collected from the Taiwan Quake Catcher Network (QCN-Taiwan) in 2012 to extract the building response of the Science Education Center, National Taiwan Normal University. The QCN-Taiwan project is mainly aimed to construct a school seismic network with low-cost sensors for the purpose of earthquake science education in Taiwan. So far there are more than 60 volunteer QCN sites deployed island-wide in the campus of Taiwan. There were 10 MEMS sensors deployed in the basement and every story from 1 to 8 in the building. We analyze the acceleration data generated from 3 moderate to strong earthquakes (6.4?ML?5.2) to study the characteristic frequencies and responses of the building. Both deconvolution and H/V spectral ratio methods are used to characterize the building response. The dominant frequency in the NS direction is 1.7-1.9 Hz, which is slightly higher than recorded in the EW direction of 1.65-1.8 Hz. In addition, the amplification is much significant in levels higher than the 3rd floor in the frequency range of 1-3 Hz as shown in the H/V spectral ratio diagrams. We deconvolve all waveforms with both the motions in the ground and top floors to derive the building responses, respectively. Results show that the 1.6 Hz resonance is dominant in levels higher than the 4th floor for waveforms deconvolved with the basement data. On the other hand, both the up-going and down-going shear waves are clearly seen in the waveforms deconvoled with top floor data, which tells a shear velocity of ~190 m/s. We have proven that the strong motion data collected by the low-cost QCN MEMS sensors during large earthquakes is useful for extracting the building response.
Liang, W.; Lee, W.; Chen, K. H.; Yen, E. H.; Lawrence, J. F.; Lin, C.; Chang, C.
Estimation of slip scenarios of mega-thrust earthquakes and strong motion simulations for Central Andes, Peru
NASA Astrophysics Data System (ADS)
We have developed a methodology for the estimation of slip scenarios for megathrust earthquakes based on a model of interseismic coupling (ISC) distribution in subduction margins obtained from geodetic data, as well as information of recurrence of historical earthquakes. This geodetic slip model (GSM) delineates the long wavelength asperities within the megathrust. For the simulation of strong ground motion it becomes necessary to introduce short wavelength heterogeneities to the source slip to be able to efficiently simulate high frequency ground motions. To achieve this purpose we elaborate "broadband" source models constructed by combining the GSM with several short wavelength slip distributions obtained from a Von Karman PSD function with random phases. Our application of the method to Central Andes in Peru, show that this region has presently the potential of generating an earthquake with moment magnitude of 8.9, with a peak slip of 17 m and a source area of approximately 500 km along strike and 165 km along dip. For the strong motion simulations we constructed 12 broadband slip models, and consider 9 possible hypocenter locations for each model. We performed strong motion simulations for the whole central Andes region (Peru), spanning an area from the Nazca ridge (16^o S) to the Mendana fracture (9^o S). For this purpose we use the hybrid strong motion simulation method of Pulido et al. (2004), improved to handle a general slip distribution. Our simulated PGA and PGV distributions indicate that a region of at least 500 km along the coast of central Andes is subjected to a MMI intensity of approximately 8, for the slip model that yielded the largest ground motions among the 12 slip models considered, averaged for all assumed hypocenter locations. This result is in agreement with the macroseismic intensity distribution estimated for the great 1746 earthquake (M~9) in central Andes (Dorbath et al. 1990). Our results indicate that the simulated PGA and PGV for all scenario slips for central Andes, and for an average soil condition, exhibit similar amplitudes and attenuation characteristics with distance as the PGA and PGV values observed during the 2010 Maule (Mw 8.8), and 2011 Tohoku-oki (Mw 9.0) earthquakes. Our results clearly indicate that the simulated ground motions for scenarios with deep rupture nucleations (~40 km) are consistently smaller than the ground motions obtained for shallower rupture nucleations. We also performed strong ground motion simulations in metropolitan Lima by using the aforementioned slip scenarios, and incorporating site amplifications obtained from several microtremors array surveys conducted at representative geotechnical zones in this city. Our simulated PGA and PGV in Lima reach values of 1000 cm/s^2 and 80 cm/s. Our results show that the largest values of PGA (at Puente Piedra district, Northern Lima) are related with short period site effects, whereas the largest values of PGV are related with large site amplifications for periods from 1s to 1.5s (at Callao, Villa el Salvador and La Molina districts). Our results also indicate that the simulated PGA and PGV in central Lima (Parque de la Reserva) are in average 2~3 times larger than the values recorded by a strong motion instrument installed at this location, during the 1974 (Mw8.0) and 1966 (Mw8.0) earthquakes off-shore Lima.
Pulido, N.; Tavera, H.; Aguilar, Z.; Chlieh, M.; Calderon, D.; Sekiguchi, T.; Nakai, S.; Yamazaki, F.
Modeling of strong ground motion during the 1992 Cairo earthquake in the urban area northern Greater of Cairo, Egypt
NASA Astrophysics Data System (ADS)
The 1992 Cairo earthquake originated from Dahshour seismic zone at an epicentral distance of about 25 km southwest of Cairo. Regardless of its relatively moderate magnitude (Mb = 5.8), it caused extensive property damage besides injuries and loss of lives. The significant damage of this earthquake was probably associated with amplification of seismic waves due to local site effects. Liquefaction was observed at many sites near the epicenter. There are no records of strong ground motion at the damaged area during this earthquake. The main shock was recorded only by the local Kattamya station (KEG) constructed in limestone rock site at about 46-48 km east of Cairo. In the present work, the strong ground motion during 1992 Cairo earthquake was analyzed and the possible causes of damage and structural failure were discussed. The study area is located at the southern part of Cairo city, holding heavy population and many public structures and strategic buildings. The ground motion parameters in terms of peak ground acceleration (PGA), peak ground velocity (PGV), and pseudo-spectral acceleration (PSA) were estimated for each site in the study area and in the KEG site. The site-dependent spectral models together with the stochastic technique were applied for this purpose, using the Fourier amplitude spectrum (FAS) source scaling, attenuation model, and the site amplification functions. The peak ground acceleration of the studied area, comprising 89 sites in northern great of Cairo (Qalyoub city) was calculated. The calculated peak ground acceleration values indicate the sites of high values of peak ground acceleration which are also characterized by high ground motion amplification factors. The ground motion, which is presented in this study, is highly amplified by the soil layer covering the area. Otherwise, the surface layer must be totally removed before construction of the buildings to avoid its large amplification to the ground motion.
Omar, Khaled; Attia, Mohsen; Fergany, El Sayed; Hassoup, Awad; Elkhashab, Hussein
NSDL National Science Digital Library
This website, from the National Taiwan Normal University, provides a demonstration of Kepler's laws of planetary motion. The site offers a description of all three laws and a brief history of Johann Kepler and his discoveries. The applet can be adjusted to display several different variables of planetary motion to simulate each law effectively.
Hwang, Fu-Kwun
Ground-motion Attenuation Relation from Strong-motion Records of the 2001 Mw 7.7 Bhuj Earthquake Sequence (2001-2006), Gujarat, India
NASA Astrophysics Data System (ADS)
Predictive relations are developed for peak ground acceleration (PGA) from the engineering seismoscope (SRR) records of the 2001 Mw 7.7 Bhuj earthquake and 239 strong-motion records of 32 significant aftershocks of 3.1 ? Mw ? 5.6 at epicentral distances of 1 ? R ? 288 km. We have taken advantage of the recent increase in strong-motion data at close distances to derive new attenuation relation for peak horizontal acceleration in the Kachchh seismic zone, Gujarat. This new analysis uses the Joyner-Boore�s method for a magnitude-independent shape, based on geometrical spreading and anelastic attenuation, for the attenuation curve. The resulting attenuation equation is, eqalign{ ln ({Y}) = -7.9527 + 1.4043 {M}_{{W}} - ln left( {{r}_{{jb}}2 + 19.822} right)^{1/2} - 0.0682 {S} ?{for} 3.1 { < M}_{{W}} le 7.7quad quad {std}. {dev}. left(? right): � 0.8243, ?} where, Y is peak horizontal acceleration in g, Mw is moment magnitude, rjb is the closest distance to the surface projection of the fault rupture in kilometers, and S is a variable taking the values of 0 and 1 according to the local site geology. S is 0 for a rock site, and, S is 1 for a soil site. The relation differs from previous work in the improved reliability of input parameters and large numbers of strong-motion PGA data recorded at short distances (0-50 km) from the source. The relation is in demonstrable agreement with the recorded strong-ground motion data from earthquakes of Mw 3.5, 4.1, 4.5, 5.6, and 7.7. There are insufficient data from the Kachchh region to adequately judge the relation for the magnitude range 5.7 ? Mw ? 7.7. But, our ground-motion prediction model shows a reasonable correlation with the PGA data of the 29 March, 1999 Chamoli main shock (Mw 6.5), validating our ground-motion attenuation model for an Mw6.5 event. However, our ground-motion prediction shows no correlation with the PGA data of the 10 December, 1967 Koyna main shock (Mw 6.3). Our ground-motion predictions show more scatter in estimated residual for the distance range (0-30 km), which could be due to the amplification/noise at near stations situated in the Kachchh sedimentary basin. We also noticed smaller residuals for the distance range (30-300 km), which could be due to less amplification/noise at sites distant from the Kachchh basin. However, the observed less residuals for the longer distance range (100-300 km) are less reliable due to the lack of available PGA values in the same distance range.
Mandal, Prantik; Kumar, N.; Satyamurthy, C.; Raju, I. P.
Slip history of the 2003 San Simeon earthquake constrained by combining 1-Hz GPS, strong motion, and teleseismic data
The slip history of the 2003 San Simeon earthquake is constrained by combining strong motion and teleseismic data, along with GPS static offsets and 1-Hz GPS observations. Comparisons of a 1-Hz GPS time series and a co-located strong motion data are in very good agreement, demonstrating a new application of GPS. The inversion results for this event indicate that the rupture initiated at a depth of 8.5 km and propagated southeastwards with a speed ???3.0 km/sec, with rake vectors forming a fan structure around the hypocenter. We obtained a peak slip of 2.8 m and total seismic moment of 6.2 ?? 1018 Nm. We interpret the slip distribution as indicating that the hanging wall rotates relative to the footwall around the hypocenter, in a sense that appears consistent with the shape of the mapped fault trace. Copyright 2004 by the American Geophysical Union.
Ji, C.; Larson, K. M.; Tan, Y.; Hudnut, K. W.; Choi, K.
Equation of motion for relativistic compact binaries with the strong field point particle limit: Third post-Newtonian order
NASA Astrophysics Data System (ADS)
An equation of motion for relativistic compact binaries is derived through the third post-Newtonian (3PN) approximation of general relativity. The strong field point-particle limit and multipole expansion of the stars are used to solve iteratively the harmonically relaxed Einstein equations. We take into account the Lorentz contraction on the multipole moments defined in our previous works. We then derive a 3PN acceleration of the binary orbital motion of the two spherical compact stars based on a surface integral approach which is a direct consequence of local energy momentum conservation. Our resulting equation of motion admits a conserved energy (neglecting the 2.5PN radiation reaction effect), is Lorentz invariant, and is unambiguous: there exist no undetermined parameters reported in the previous works. We shall show that our 3PN equation of motion agrees physically with the Blanchet-Faye 3PN equation of motion if ?=-1987/3080, where ? is the parameter which is undetermined within their framework. This value of ? is consistent with the result of Damour, Jaranowski, and Sch�fer, who first completed a 3PN iteration of the ADM Hamiltonian in the ADMTT gauge using dimensional regularization.
Itoh, Yousuke
A Web-Based Borehole Strong-motion Data Dissemination Portal
Accelerometric and pore pressure data from instrumented boreholes in southern California are producing very interesting observations from a large data set that includes 100's of earthquake observations each month. While the majority of these are very small events, they provide the control data that represents the linear behavior of the site. In addition, the largest motions recorded to date, ~10%g,
J. H. Steidl; S. Seale; H. Ratzesberger; F. Civilini; N. Vaughan
Revelations from a single strong-motion record retreived during the 27 June 1998 Adana (Turkey) earthquake
During the 27 June 1998 Adana (Turkey) earthquake, only one strong-motion record was retrieved in the region where the most damage occurred. This single record from the station in Ceyhan, approximately 15 km from the epicenter of that earthquake, exhibits characteristics that are related to the dominant frequencies of the ground and structures. The purpose of this paper is to explain the causes of the damage as inferred from both field observations and the characteristics of a single strong-motion record retrieved from the immediate epicentral area. In the town of Ceyhan there was considerable but selective damage to a significant number of mid-rise (7-12 stories high) buildings. The strong-motion record exhibits dominant frequencies that are typically similar for the mid-rise building structures. This is further supported by spectral ratios derived using Nakamura's method [QR of RTRI, 30 (1989) 25] that facilitates computation of a spectral ratio from a single tri-axial record as the ratio of amplitude spectrum of horizontal component to that of the vertical component [R = H(f)/V(f)]. The correlation between the damage and the characteristics exhibited from the single strong-motion record is remarkable. Although deficient construction practices played a significant role in the extent of damage to the mid-rise buildings, it is clear that site resonance also contributed to the detrimental fate of most of the mid-rise buildings. Therefore, even a single record can be useful to explain the effect of site resonance on building response and performance. Such information can be very useful for developing zonation criteria in similar alluvial valleys. Published by Elsevier Science Ltd.
Celebi, M.
Source Process and Near-source Strong Ground Motion Generation of the 2004 Mid Niigata Prefecture (Chuetsu), Japan, Earthquake
NASA Astrophysics Data System (ADS)
The 2004 Mid Niigata Prefecture Earthquake occurred on October 23, 2004 in the central Japan with large strong ground motions in the near source region. We estimate a source rupture process of this event using strong motion records. Then we simulate strong ground motions in the source area using the obtained source model together with the three-dimensional underground structure model derived by Yamanaka et al. (2005). To obtain a source model we performed the kinematic linear waveform inversion using multiple time-windows by Sekiguchi et al. (2000). We assumed the hypocenter and the fault plane by event relocation research studies (Kato et al., 2005; Okada et al., 2005; Shibutani et al., 2005). We used the S-wave portion of velocity waveforms that were bandpass-filterd between 0.05
Iwata, T.; Asano, K.; Yamanaka, H.; Yamada, N.; Fukumoto, S.
Finite-Fault Modeling of Strong Ground Motions for the 1995, Mw 8, Colima-Jalisco, Mexico, Earthquake
NASA Astrophysics Data System (ADS)
The 9 October 1995 Colima-Jalisco subduction earthquake (Ms 7.4, Mw 8.0) occurred in the Middle American Trench, about 35 km southwest of Manzanillo, Mexico, producing considerable damage for buildings located near the epicentral area. Notable damage was also reported in the city of Guadalajara with an epicentral distance of about 240 km due to local site effects (Chavez, 1998). Here, three-component strong ground motion records were obtained for the mainshock as well as for the 6 October foreshock and 12 October aftershock at a station equipped with an SSA-2 (soil, 9 m depth) and two FDH23 Kinemetrics (rock, 35 m depth) accelerographs in the free field. In this study we present broadband synthetics for the strong motion records of the mainshock using a hybrid method combining long-period and high-frequency simulations. The long-period (< 1 Hz) wavefield was simulated using a 4th-order finite-difference method including a finite-fault description of the source with 4 asperities in a 2.5D model constrained by gravity data. The high-frequency (> 1 Hz) synthetics were generated with empirical Green functions including recordings of the fore- and aftershocks. Compared to the strong motion data our synthetics show a good fit for both the long-period waveforms and high-frequency spectra.
Chavez, M.; Olsen, K. B.
Strong ground motion simulation during the November 1759 Earthquake along Serghaya Fault in the metropolitan of Damascus, Syria
NASA Astrophysics Data System (ADS)
The seismic hazard potential for metropolitan of Damascus, Syria is mainly controlled by earthquakes along Serghaya Fault which is a branch of Dead Sea Fault System. In this study, strong ground motion due to the November 1759 Earthquake along the fault of Serghaya was estimated with a numerical simulation technique. In the simulation, the Kostrov-like slip-velocity function was used as an input to the discrete wave number method to simulate the strong ground motions in a broadband frequency range. In order to model the incoherent rupture propagation which can excite large high-frequency waves, random numbers are added to arrival time of circular rupture front. MMI intensities calculated from the synthetic ground motions are compared with the observed values by Ambraseys and Barazangi (J Geophys Res 94:4007-4013, 1989). The calculated intensities are in good agreement with the observed ones at the most sites that validate appropriateness of the proposed source model. The PGA and PGV in the eastern region of Damascus city are higher than those in the western region due to the effects of local site amplification. The simulated high-frequency (1.0-6.0 Hz) ground motions for the sites in the Damascus city are higher than the design requirements defined by the Syrian building code. Furthermore, the simulated high-frequency ground motions for sites in the focal region are bigger than the design requirements in the case of the near-fault factors and are not considered. That demonstrates the appropriateness of considering the near-fault factors for a site near the focal region as introduced by the new building code.
Zaineh, Hussam Eldein; Yamanaka, Hiroaki; Dhakal, Yadab Prasad; Dakkak, Rawaa; Daoud, Mohamad
Response of the Tarzana strong motion site during the 1994 Northridge earthquake
Exceptionally high ground motions (horizontal peak ground acceleration (PGA) of 1.82g) were recorded at the Tarzana Station during the main shock of the 1994 Northridge earthquake (moment magnitude 6.7 at an epicentral distance of 6km). At the time of the main shock, the instrument was located near the edge of a 21m-high ridge with side slopes ranging from 3H:1V to
Shahriar Vahdani; Scott Wikstrom
Surface-to-base amplification evaluated from KiK-net vertical array strong motion records
Site amplification defined as the peak value of spectrum ratio was investigated using surface and base accelerations recorded in a number of KiK-net down-hole arrays in Japan during three major earthquakes. An important task was to determine the spectral amplifications relative to outcropping motions with the aid of the down-hole array records. Based on soil data available for individual arrays,
Takaji Kokusho; Katsuharu Sato
Modeling nonlinear roll damping with a self-consistent, strongly nonlinear ship motion model
Appropriate modeling of roll damping is one of the key issues in accurately predicting ship roll motion. The difficulties\\u000a in modeling roll damping arise from the nonlinear nature of the phenomena. In this study, we report a new effort in modeling\\u000a the bilge keel roll damping effect based on the blocking mechanisms of an object in the potential flow. This
Ray-Qing Lin; Weijia Kuang
Calculation of broadband time histories of ground motion: Comparison of methods and validation using strong-ground motion from the 1994 Northridge earthquake
This article compares techniques for calculating broadband time histories of ground motion in the near field of a finite fault by comparing synthetics with the strong-motion data set for the 1994 Northridge earthquake. Based on this comparison, a preferred methodology is presented. Ground-motion-simulation techniques are divided into two general methods: kinematic- and composite-fault models. Green's functions of three types are evaluated: stochastic, empirical, and theoretical. A hybrid scheme is found to give the best fit to the Northridge data. Low frequencies ( 1 Hz) are calculated using a composite-fault model with a fractal subevent size distribution and stochastic, bandlimited, white-noise Green's functions. At frequencies below 1 Hz, theoretical elastic-wave-propagation synthetics introduce proper seismic-phase arrivals of body waves and surface waves. The 3D velocity structure more accurately reproduces record durations for the deep sedimentary basin structures found in the Los Angeles region. At frequencies above 1 Hz, scattering effects become important and wave propagation is more accurately represented by stochastic Green's functions. A fractal subevent size distribution for the composite fault model ensures an ??-2 spectral shape over the entire frequency band considered (0.1-20 Hz).
Hartzell, S.; Harmsen, S.; Frankel, A.; Larsen, S.
Ground Motions at a Network of Strong Motion Accelerometers on the Hanford Site, Southeastern Washington, From the 28 February 2001 Nisqually Earthquake
NASA Astrophysics Data System (ADS)
We have been operating five free-field strong motion accelerometers (SMA) at locations near the facilities on the Hanford Site since November 1998. The 28 February 2001 Nisqually earthquake was the first earthquake to be recorded by these instruments. The USGS and Caltech each operate one additional SMA/broadband seismometer site at Hanford (stations HAWA and LTH). Taken together, the elements of this network have an inter-station spacing of 8-12 km. The distance range of the instruments from the epicenter is 245-277 km. Peak ground accelerations ranged from 0.0016 to 0.0035 g (vertical), from 0.0017 to 0.0057 g (radial), and from 0.0022 to 0.0064 g (transverse). The lowest accelerations were observed at the bedrock site HAWA, but accelerations at another station on soil (H300A) were not significantly larger. The other stations on soil show significant amplification across the frequency spectrum and also within variable, narrow frequency ranges. For example, Fourier spectra from the station H100K, the furthest north of these stations, shows nearly a factor of 10 amplification of the transverse ground acceleration in the frequency range 0.5 to 1.0 Hz relative to the bedrock station. We are investigating the differences in soil geology beneath the network of SMA stations to understand these effects. The ground motions recorded from this earthquake are significantly lower than those predicted by intra-slab earthquake ground motion attenuation relationships that were used for Hanford's probabilistic seismic hazard assessment. Although these relationships include statistical variation in ground motion, they do not predict the range of amplification determined at the soil sites for this earthquake. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy under contract DE-AC06-76RL01830.
Rohay, A.; Reidel, S.; Hartshorn, D.; Valenta, M.
Ground motion and rupture process of the 2004 Mid Niigata Prefecture earthquake obtained from strong motion data of K-NET and KiK-net
NASA Astrophysics Data System (ADS)
The 2004 Mid Niigata Prefecture earthquake (37.289�N, 138.870�E, 13.1 km, MJMA 6.8; JMA), also known as the 2004 Niigata Prefecture Chuetsu earthquake, was a thrust type earthquake that occurred on October 23, 2004 at 17:56 (JST). Strong ground motions of PGA 800-1700 cm/s2 and PGV 60-130 cm/s were observed at stations located immediately above the source region. We deduced the rupture process of this earthquake with a multi-time-window linear waveform inversion procedure. We used near-fault strong ground motion data observed at nine K-NET and KiK-net stations within 50 km from the epicenter. In order to obtain appropriate Green's functions for the waveform inversion, we constructed two velocity structure models for stations on the hanging wall and one structure model for stations on the footwall. The estimated total slip distribution contains three asperities: (a) around the hypocenter, (b) in the upper-middle section of the fault plane, and (c) southwest of the hypocenter. The maximum slip is 3.8 m at the hypocenter and the total seismic moment is 12 � 1019 Nm, which corresponds to Mw =6.7. The moment rate functions in asperities (a) and (c) have a short rise time, while those in asperity (b) have a longer rise time.
Honda, R.; Aoi, S.; Morikawa, N.; Sekiguchi, H.; Kunugi, T.; Fujiwara, H.
Ground motion and rupture process of the 2003 Tokachi-oki earthquake obtained from strong motion data of K-NET and KiK-net
NASA Astrophysics Data System (ADS)
A great earthquake, named the 2003 Tokachi-oki earthquake, occurred in the southern Kuril subduction zone on 26th September 2003, 4:50 JST (41.7797�N, 144.0795�E, 42 km depth; Japan Meteorological Agency). Its ground motion was recoreded at 655 stations of the nationwide strong motion networks, K-NET and KiK-net. A maximum peak ground acceleration of 988 cm/s2 (gal) was observed at station HKD100 and amplitudes greater than 200 cm/s2 were observed over a wide area of eastern Hokkaido. We used a multi-line linear waveform inversion method to estimate the rupture process from the strong motion data of supplied by 15 stations. We assumed a fault plane model of 140 km � 160 km with strike and dip angles of our fault model are N246�E and 18�, respectively, placed on the estimated upper boundary of the subducting Pacific Plate. The estimated total slip distribution consisted of three major slip areas; (a) around the hypocenter, (b) the northwest part of the fault with the maximum slip of 5.9 m, and (c) the northeast edge of the fault plane. The major asperity (b) was composed of two large slip areas with different slip rate functions: the duration of moment release in the sourtheast part is longer than 15 sec, but in contrast most of the seismic moment of the northwest part was released in a short period of less than 10 sec. Our estimation of the total seismic moment was 2.9 � 1021 N�m which corresponded to Mw = 8.2.
Honda, R.; Aoi, S.; Morikawa, N.; Sekiguchi, H.; Kunugi, T.; Fujiwara, H.
Real-time coseismic displacements from tightly-integrated processing of high-rate GNSS and strong motion data
NASA Astrophysics Data System (ADS)
Precise point positioning (PPP), which can provide "absolute" coseismic displacements with respect to a global reference frame (defined by the satellite orbits and clocks) with a stand-alone GNSS receiver, is advantageous and being used more and more widely for high-rate GNSS seismology. Following the availability of real-time high-rate GNSS observations and precise satellite orbit and clock products, the interest in the real-time PPP technique has greatly increased to construct displacement waveforms and to invert for source parameters of earthquakes in real time. Furthermore, PPP ambiguity fixing approaches developed in recent years provide an important promise to overcome the accuracy limitation of the traditional PPP float solution and to achieve comparable accuracy with relative/network positioning. The main weaknesses of current GNSS measurements are the lower sampling rates (1~50Hz) and the larger high-frequency noise contribution compared to the seismic sensors. Strong motion sensors are able to sample at very high rates (e.g. 200Hz) and perform very well in the high-frequency range as it is much more sensitive to ground motions than GNSS receiver, especially in the vertical direction. However, the double integration is accompanied by unphysical drifts due to sensor rotation and tilt, hysteresis, and imprecision in the numerical integration process. GNSS and seismic instruments are mutually beneficial for geophysical applications because weaknesses of one observation technique are offset by strengths in the other. In order to take full use of the complementary of GNSS and strong motion sensors, we propose an approach of integrating the strong motion data into the real-time ambiguity-fixed PPP processing. A tightly-integrated filter is developed to estimate coseismic displacements from raw GNSS phase and pseudorange observations and raw strong motion data. The performance of the proposed tightly-integrated approach was demonstrated using the collocated high-rate GNSS and strong motion data collected during the 2010, Mw 7.2 El Mayor-Cucapah earthquake(Mw 7.2, 4 April, 2010) in Baja California, Mexico. Taking advantage of the greater precision of the accelerometer observations, small-amplitude P-wave arrivals can be detected in the integrated solution. That is not detectable in the GNSS-only approach because of the reduced sensitivity of GNSS especially in vertical component. On the other hand, the seismic-only solution does not show the permanent co-seismic offset correctly, but it can be obtained from the integrated solution exactly. Furthermore, the proposed tightly-integrated algorithm can significantly improve the ability of resolving integer-cycle phase ambiguities in real-time scenarios, which is required to derive displacements with highest accuracy. Based on the integrated results, we detected the P-wave arrival, located the epicenter and estimated the magnitude. The P-wave-based earthquake parameters such as epicenter and origin time can be issued before the arrival of the destructive S-wave. The reliable estimation of the earthquake magnitude is an important contribution for earthquake early warning especially in case of large magnitude earthquakes. Keywords: Real-time high-rate GNSS; strong motion sensor; tight integration; precise point positioning; PPP ambiguity fixing;
Li, Xingxing; Ge, Maorong; Zhang, Yong; Wang, Rongjiang; Klotz, J�rgen; Wickert, Jens; Schuh, Harald
Structure and dynamics of an imidazoline nitroxide side chain with strongly hindered internal motion in proteins
NASA Astrophysics Data System (ADS)
A disulfide-linked imidazoline nitroxide side chain (V1) has a similar and highly constrained internal motion at diverse topological sites in a protein, unlike that for the disulfide-linked pyrroline nitroxide side chain (R1) widely used in site directed spin labeling EPR. Crystal structures of V1 at two positions in a helix of T4 Lysozyme and quantum mechanical calculations suggest the source of the constraints as intra-side chain interactions of the disulfide sulfur atoms with both the protein backbone and the 3-nitrogen in the imidazoline ring. These interactions apparently limit the conformation of the side chain to one of only three possible rotamers, two of which are observed in the crystal structure. An inter-spin distance measurement in frozen solution using double electron-electron resonance (DEER) gives a value essentially identical to that determined from the crystal structure of the protein containing two copies of V1, indicating that lattice forces do not dictate the rotamers observed. Collectively, the results suggest the possibility of predetermining a unique rotamer of V1 in helical structures. In general, the reduced rotameric space of V1 compared to R1 should simplify interpretation of inter-spin distance information in terms of protein structure, while the highly constrained internal motion is expected to extend the dynamic range for characterizing large amplitude nanosecond backbone fluctuations.
Toledo Warshaviak, Dora; Khramtsov, Valery V.; Cascio, Duilio; Altenbach, Christian; Hubbell, Wayne L.
Evaluation model of landslide hazards induced by the 2008 Wenchuan earthquake using strong motion data
NASA Astrophysics Data System (ADS)
Landslides induced by the 2008 Wenchuan earthquake in the Longmenshan area were relatively well instrumented, which makes it possible to investigate the landslides using ground motion records. Firstly, this paper analyzes the data from Wenchuan earthquake on both regional and local site scale. The analyses show that the Newmark accumulative displacement calculated from the ground motion recorded in a particular geological hazard zone corresponds to the hazard intensity in that zone; the larger the displacement, the more serious the geologic hazard. The calculated result also shows that the displacement is related to the Arias intensity, which represents the total energy released during the earthquake at the observation site. Secondly, this paper constructs an evaluation model of Newmark displacement calculated with Arias intensities to estimate the subsequent slope failure resulting from the earthquake. The calculated results based on the model fit well with the distribution of actual landslides, suggesting that this method is useful for hazard evaluation. Therefore, this type of model can be used for estimating regional-scale distribution of earthquake-induced landslides and their associated hazards immediately after an earthquake.
Wang, Xiuying; Nie, Gaozhong; Ma, Mujun
Modeling Strong Ground Motion during the February 22 2011 M6.3 Christchurch, New Zealand, Earthquake
NASA Astrophysics Data System (ADS)
We present a simple, kinematic model of the rupture of the M6.3 February 22 2011 earthquake in the city of Christchurch, New Zealand, that provides insights into the factors influencing observed ground motions. The model is based on a rectangular 8 x 9 km fault dipping 75o, striking 64o and rupturing with a thrust mechanism. The fault is embedded in a velocity model consisting of one layer over a uniform half-space representing the stiffest soil deposit and the bedrock underneath, respectively (Brown, L.J.; Weeber, J.H. 1992). The free-surface of the soil layer is assumed to be flat, however, the bedrock interface (initially at 900 m depth) pinches out as a 3-D cosine shaped free-surface topography up to 250 m high, representing Bank's Peninsula. The base of the topography is elliptical, with principle axes of 9 km and 4.5 km. Numerical modeling of the rupture shows that the observed corresponding strong ground motion is mainly due to two factors: the coherent rupture of a section of the fault, of 25 km2 area, with 116o rake and 3.1 km/s rupture velocity, and the presence of the sediments immediately overlying the fault. The discretization of the whole fault into several subfaults each with prescribed values of slip in the range 0.4-3.0 m, and rise time, allows the parametric study of the ground motion using several rupture scenarios. The model with the coherent rupture described above best reproduces the high (1.2 g -1.8 g) accelerations observed at stations in the footwall of the fault. The incidence upon the topography appears to produce Rayleigh waves propagating away from it. This is in agreement with particle motion surface wave analysis of the measured seismograms that reveals the contribution of Rayleigh wave energy to the observed long-period ground motions. Furthermore, arrival times of the Rayleigh wave energy are consistent with predicted travel times from our basin velocity model. We reproduce prominent near-surface effects at many Christchurch strong motion stations through the addition of a shallow, thin (6m thick) layer with a high S-wave attenuation factor. The resulting seismograms exhibit about 40% less frequency content in the horizontal motion than in the vertical motion, as observed at stations located on water saturated soils. Given that no suitable rock reference station recordings were available with which to estimate site effects in the Christchurch metropolitan area, we used computed synthetic seismograms from our rupture model at the base of the soft soil column to calculate site transfer functions that describe the observed site effects at each of the strong ground motion stations.
Benites, R. A.; Fry, B.; Kaiser, A. E.
Three-dimensional attenuation (Qs) structure beneath the Kanto district, Japan, as inferred from strong motion records
NASA Astrophysics Data System (ADS)
The three-dimensional (3D) S-wave attenuation (Qs) structure beneath the Kanto plain, where the Pacific and Philippine Sea plates subduct, was estimated using strong-motion records of the K-NET and KiK-net. In addition to several low-Qs zones corresponding to the volcanic front, a large NW-SE trending low-Qs zone is estimated under the non-volcanic Kanto area at depths of 20-60 km. This zone corresponds to a previously identified low-velocity (both Vp and Vs) zone with a high Poisson's ratio at 40-km depth; it further indicates a wedge immediately above the subducting Philippine Sea plate. Predicted seismic ground motions using the estimated 3D attenuation structure is very similar to the actually recorded by recent earthquake on July 2005 (M = 6).
Nakamura, Ryoichi; Satake, Kenji; Toda, Shinji; Uetake, Tomiichi; Kamiya, Shin'ichiro
Displaced rocks, strong motion, and the mechanics of shallow faulting associated with the 1999 Hector Mine, California, earthquake
The paucity of strong-motion stations near the 1999 Hector Mine earthquake makes it impossible to make instrumental studies of key questions about near-fault strong-motion patterns associated with this event. However, observations of displaced rocks allow a qualitative investigation of these problems. By observing the slope of the desert surface and the frictional coefficient between these rocks and the desert surface, we estimate the minimum horizontal acceleration needed to displace the rocks. Combining this information with observations of how many rocks were displaced in different areas near the fault, we infer the level of shaking. Given current empirical shaking attenuation relationships, the number of rocks that moved is slightly lower than expected; this implies that slightly lower than expected shaking occurred during the Hector Mine earthquake. Perhaps more importantly, stretches of the fault with 4 m of total displacement at the surface displaced few nearby rocks on 15?? slopes, suggesting that the horizontal accelerations were below 0.2g within meters of the fault scarp. This low level of shaking suggests that the shallow parts of this rupture did not produce strong accelerations. Finally, we did not observe an increased incidence of displaced rocks along the fault zone itself. This suggests that, despite observations of fault-zone-trapped waves generated by aftershocks of the Hector Mine earthquake, such waves were not an important factor in controlling peak ground acceleration during the mainshock.
Michael, A. J.; Ross, S. L.; Stenner, H. D.
Experimental investigation of strong ground motion due to thrust fault earthquakes
NASA Astrophysics Data System (ADS)
Thrust fault earthquakes are studied in a laboratory earthquake setup previously used to investigate analog strike-slip seismic events. Dynamic mode II ruptures are generated along preexisting faults in an analog material, Homalite H-100, and their interaction with the free surface is studied for both sub-Rayleigh and supershear rupture speeds. High-speed digital photography and laser velocimeter diagnostics are used synergistically to identify and study the ground velocity signatures caused by the various features of the generated ruptures. The obtained surface-normal motions of both sub-Rayleigh and supershear ruptures show substantial asymmetry between the hanging and footwall, with the hanging wall experiencing much larger velocity amplitudes. The main features of the surface velocity traces at various stations can be explained by the calculated arrivals of various waves and fronts�Mach cones, Pand S waves, and sub-Rayleigh features. In both the sub-Rayleigh and supershear cases, the arrival of the rupture tip generates a prominent Rayleigh wave traveling along the simulated Earth's surface. Supershear events feature larger amplitudes of ground shaking profiles. All signatures in the surface motion records attenuate and broaden with increasing distance from the fault trace. The signatures corresponding to the arrival of the Mach fronts attenuate with distance at a slower rate than those from sub-Rayleigh ruptures. The arrival of the updip supershear rupture at the free surface creates a downdip propagating slip feature with its own Mach cone. These additional Mach fronts further amplify ground shaking on the hanging and footwalls.
Gabuchian, Vahe; Rosakis, Ares J.; Lapusta, Nadia; Oglesby, David D.
Effect of radiation reaction on particle motion and production in IZEST-strong fields
NASA Astrophysics Data System (ADS)
We discuss radiation physics in fields approaching the Schwinger field. Among the leading effects in such strong fields are: (1) lepton production; (2) radiation effects from highly accelerated electrons; and (3) radiation back-reaction. Once applied to multi-TeV electrons, the intense electromagnetic fields could produce radiating muons.
Sokolov, I. V.; Mourou, G. A.; Naumova, N. M.
Strong correlation of atomic thermal motion in the first coordination shell of a Cu-Zr metallic glass
We demonstrate a strong correlation of atomic thermal motions in the first coordination shell of Cu{sub 50}Zr{sub 50} metallic glass using molecular dynamics simulations, which explains directly the small thermal expansion coefficient calculated by the first maxima of pair correlation functions. The vibrational anisotropy in the glass is found to be even higher than in crystalline copper. The parallel-perpendicular anisotropy gradually decreases upon heating. The anisotropy in Zr-Zr is the strongest bonds among all the interatomic bonds, which is also very stable near the glass transition at 700 K. Structurally, the anisotropy can be correlated to Cu-centered (0 2 8 1) clusters.
Zhang, Y.; Mattern, N. [IFW Dresden, Institut fuer Komplexe Materialien, Helmholtzstrasse 20, D-01069 Dresden (Germany)] [IFW Dresden, Institut fuer Komplexe Materialien, Helmholtzstrasse 20, D-01069 Dresden (Germany); Eckert, J. [IFW Dresden, Institut fuer Komplexe Materialien, Helmholtzstrasse 20, D-01069 Dresden (Germany) [IFW Dresden, Institut fuer Komplexe Materialien, Helmholtzstrasse 20, D-01069 Dresden (Germany); Institut fuer Werkstoffwissenschaft, Technische Universitaet Dresden, D-01062 Dresden (Germany)
Strong correlation of atomic thermal motion in the first coordination shell of a Cu-Zr metallic glass
NASA Astrophysics Data System (ADS)
We demonstrate a strong correlation of atomic thermal motions in the first coordination shell of Cu50Zr50 metallic glass using molecular dynamics simulations, which explains directly the small thermal expansion coefficient calculated by the first maxima of pair correlation functions. The vibrational anisotropy in the glass is found to be even higher than in crystalline copper. The parallel-perpendicular anisotropy gradually decreases upon heating. The anisotropy in Zr-Zr is the strongest bonds among all the interatomic bonds, which is also very stable near the glass transition at 700 K. Structurally, the anisotropy can be correlated to Cu-centered (0 2 8 1) clusters.
Zhang, Y.; Mattern, N.; Eckert, J.
Strong motion characteristics of the 2011 Tohoku-Oki earthquake observed by K-NET and KiK-net
NASA Astrophysics Data System (ADS)
The Tohoku-Oki earthquake was the largest earthquake occurred in and around Japan since the recorded history. This magnitude 9.0 megathrust earthquake initiated approximately 100 km off-shore Miyagi prefecture and the rupture extended 400 - 500 km along the subducting Pacific plate. Due to the large ground motions and tsunami associated by this event, more than twenty thousands people were killed or missing and more than 220 thousands houses and buildings were totally or partially destroyed. The Tohoku-Oki earthquake was the first M9-class earthquake that is closely recorded by a dense seismograph network. In this paper, we summarize the characteristics of the strong motions and the source process revealed by those data. The ground motions were recorded at more than 1200 K-NET and KiK-net stations. The peak ground accelerations (PGA) exceeded 1g at 20 sites and the largest PGA, 2933 gals, was observed at the K-NET Tsukidate station (MYG004). We estimated the precise spatial distribution of seismic intensity from the observed data considering the near-surface amplification, and found that roughly twenty million people were exposed to a shaking larger than JMA seismic intensity 5+ (>MMI 7). Huge numbers of large aftershocks and triggered earthquakes including M7-class crustal and intraslab earthquakes have been recorded. Those earthquakes occurred not only in the source area but also several hundreds kilometers away. Some of them were located much nearer to the populated urban areas than the main shock and human fatalities as well as severe building damages were caused by large ground shakings. The observed waveforms from the main shock are very complex; depending on the region, accelerograms show one to three conspicuous and long-duration phases as well as several phases with smaller amplitudes and shorter durations. A paste-up of accelerograms in Iwate, Miyagi and Fukushima prefectures ordered by latitude from north displays an initial strong seismic phase first observed at Miyagi stations and then propagating towards the north and south. A subsequent phase uniformly delayed by approximately 40 s is also clearly observed in the paste-up. In the southern region, Ibaraki and Chiba prefectures, only one distinct phase is observed. Fault rupture process inverted by a multi-time window analysis using the strong-motion waveforms is characterized by one large slip area with maximum slip of 48 m which extends from the area near the hypocenter toward the shallow part of the fault plane, far off the coast of Iwate, Miyagi and Fukushima prefectures (Suzuki et al., 2011, AGU fall meeting). Though the distribution of the total slip is simple, the feature of the rupture progression is very complicated. The duration and the timing of the slip have a large spatial variety within the fault. The fault slip near the coast off Miyagi prefecture, which is small compared to the peak fault slip, had a large contribution to the observed strong motions in Miyagi and Iwate prefectures. The complicated relationship between the rupture model derived using long period strong motions and the features of the observed acceleration waveforms suggests a frequency dependency of the seismic wave radiation and source process.
Aoi, S.; Kunugi, T.; Suzuki, W.; Morikawa, N.; Nakamura, H.; Pulido Hernandez, N. E.; Fujiwara, H.
Unbound motion of massive particles in the Schwarzschild metric: Analytical description in case of strong deflection
NASA Astrophysics Data System (ADS)
Deflection angles of massive test particles moving along an unbound trajectory in the Schwarzschild metric are considered for the case of large deflection. We analytically consider the strong deflection limit, which is opposite to the commonly applied small deflection approximation and corresponds to the situation when a massive particle moves from infinity, makes several revolutions around a central object, and goes to infinity. For this purpose we rewrite an integral expression for the deflection angle as an explicit function of the parameters determining the trajectory and expand it. Remarkably, in the limiting case of strong deflection, we succeed in deriving for the first time the analytical formulas for deflection angles as explicit functions of parameters at infinity. In particular, we show that in this case the deflection angle can be calculated as an explicit function of the impact parameter and velocity at infinity beyond the usual assumption of small deflection.
Tsupko, Oleg Yu.
3D simulation of near-fault strong ground motion: comparison between surface rupture fault and buried fault
NASA Astrophysics Data System (ADS)
In this paper, near-fault strong ground motions caused by a surface rupture fault (SRF) and a buried fault (BF) are numerically simulated and compared by using a time-space-decoupled, explicit finite element method combined with a multi-transmitting formula (MTF) of an artificial boundary. Prior to the comparison, verification of the explicit element method and the MTF is conducted. The comparison results show that the final dislocation of the SRF is larger than the BF for the same stress drop on the fault plane. The maximum final dislocation occurs on the fault upper line for the SRF; however, for the BF, the maximum final dislocation is located on the fault central part. Meanwhile, the PGA, PGV and PGD of long period ground motions (?1 Hz) generated by the SRF are much higher than those of the BF in the near-fault region. The peak value of the velocity pulse generated by the SRF is also higher than the BF. Furthermore, it is found that in a very narrow region along the fault trace, ground motions caused by the SRF are much higher than by the BF. These results may explain why SRFs almost always cause heavy damage in near-fault regions compared to buried faults.
Liu, Qifang; Yuan, Yifan; Jin, Xing
Strong seismic wave scattering beneath Kanto region derived from dense K-NET/KiK-net strong motion network and numerical simulation
NASA Astrophysics Data System (ADS)
Observed seismograms, which consist of the high-frequency body waves through the low-velocity (LV) region at depth of 20-40 km beneath northwestern Chiba in Kanto, show strong peak delay and spindle shape of S waves. By analyzing dense seismic records from K-NET/KiK-net, such spindle-shape S waves are clearly observed in the frequency range of 1-8 Hz. In order to investigate a specific heterogeneous structure to generate such observations, we conduct 3-D finite-difference method (FDM) simulation using realistic heterogeneous models and compare the simulation results with dense strong motion array observations. Our 3-D simulation model is covering the zone 150 km by 64 km in horizontal directions and 75 km in vertical direction, which has been discretized with uniform grid size 0.05 km. We assume a layered background velocity structure, which includes basin structure, crust, mantle and subducting oceanic plate, base on the model proposed by Koketsu et al. (2008). In order to introduce the effect of seismic wave scattering, we assume a stochastic random velocity fluctuation in each layer. Random velocity fluctuations are characterized by exponential-type auto-correlation function (ACF) with correlation distance a = 3 km and rms value of fluctuation e = 0.05 in the upper crust, a = 3 km and e = 0.07 in the lower crust, a = 10 km and e = 0.02 in the mantle. In the subducting oceanic plate, we assume an anisotropic random velocity fluctuation characterized by exponential-type ACF with aH = 10 km in horizontal direction, aZ = 0.5 km in vertical direction and e = 0.02 (e.g., Furumura and Kennett, 2005). In addition, we assume a LV zone at northeastern part of Chiba with depth of 20-40 km (e.g., Matsubara et al., 2004). In the LV zone, random velocity fluctuation characterized by Gaussian-type ACF with a = 1 km and e = 0.07 is superposed on exponential-type ACF with a = 3 km and e = 0.07, in order to modulate the S-wave propagation in the dominant frequency range of spindle-shape S waves. Such large-scale FDM simulations are conducted on the Earth Simulator at JAMSTEC. It is found that the FDM simulation of the model without strong velocity fluctuation cannot explain the characteristics of observed S waves. By introducing strong velocity fluctuation in the LV zone, strong peak delay and spindle-shape S waves observed at central and southern part of Chiba are simulated successfully. In addition, the strong amplitude decrease of S waves in the LV zone due to strong seismic scattering is good corresponding to results based on the tomographic study of Q in Kanto (e.g., Nakamura et al., 2006). Simulation results demonstrated that strong velocity fluctuation in the LV zone plays important role in the peak delay and waveform shape. The LV zone beneath northeastern Chiba is considered as a result of dehydration from oceanic crust of subducted Philippine Sea plate (e.g., Matsubara et al., 2005). Therefore strong small-scale velocity fluctuation in the LV zone may be related with dehydrated water.
Takemura, S.; Yoshimoto, K.
Executive Summary of Vision and Options for the Future of the US National Strong-Motion Program
These reports are presented in response to a charge of the Earthquake Hazards Reduction Program (EHRP) Program Council of the U.S. Geological Survey to 'define the future of the USGS National Strong-Motion Program (NSMP)' (Appendix A). The council requested that a 'Vision Paper' and an 'Options Document' be prepared. Each of these reports is a separate document. The 'Executive Summary' of both reports is presented here under separate cover. The content of the reports and the executive summary is organized to the extent possible according to the main charges of the EHRP Program Council. Detailed evaluation of charges and questions posed by the Council with the benefit of modern GIS tools and the recent deliberations of three national workshops have yielded substantial new insight regarding the status of strong-motion measurement in the US. These reports are intended as an objective evaluation of the nation's need and capability to record the next major earthquake at locations of most significance for public safety.
Committee for the Future of the US National Strong-Motion Program
High Frequency Cut-off Characteristics of Strong Ground Motion Records at Hard Sites, Subduction and Intra-Slab Earthquakes
NASA Astrophysics Data System (ADS)
A study on high frequency cut-off characteristics of strong ground motion is presented for subduction and intra- slab earthquakes in Japan. In the latest decade, observed records at hard sites are published by NIED, National Research Institute for Earth Science and Disaster Prevention, and JCOLD, Japan Commission on Large Dams. Especially, KiK-net and K-NET maintained by NIED have been providing high quality data to study high-frequency characteristics. Kagawa et al.(2003) studied the characteristics for crustal earthquakes. We apply the same methodology to the recently observed Japanese records due to subduction and intra-slab earthquakes. We assume a Butterworth type high-cut filter with limit frequency (fmax) and its power factor. These two parameters were derived from Fourier spectrum of observed records fitting the theoretical filter shape. After analyzing the result from view points of site, path, or source effects, an averaged filter model is proposed with its standard deviation. Kagawa et al.(2003) derived average as 8.3 Hz with power factor of 1.92. It is used for strong ground motion simulation. We will propose parameters for the high-cut filters of subduction and intra-slab earthquakes and compare them with the results by Kagawa et al.(2003). REFERENCES: Kagawa et al. (2003), 27JEES (in Japanese with English Abstract).
Kagawa, T.; Tsurugi, M.; Irikura, K.
A Web-Based Borehole Strong-motion Data Dissemination Portal
NASA Astrophysics Data System (ADS)
Accelerometric and pore pressure data from instrumented boreholes in southern California are producing very interesting observations from a large data set that includes 100�s of earthquake observations each month. While the majority of these are very small events, they provide the control data that represents the linear behavior of the site. In addition, the largest motions recorded to date, ~10%g, are getting to the regime where nonlinear soil behavior effects become important. In order to make these data more accessible to the seismology and earthquake engineering research community, software development of a web-based data dissemination portal has taken place under the George E. Brown Jr., Network for Earthquake Engineering (NEES) program. This development includes processing and analysis tools, and web-based data dissemination available through the NEES@UCSB website [http://nees.ucsb.edu]. Of interest to the research community are the tools developed to provide search, waveform viewing, and download capabilities for access to data acquired through the various borehole-monitoring programs at UC Santa Barbara. Researchers interested in obtaining data recorded at the various field sites can use the map-based search tool to select a particular station and instrument(s). The user is then provided another map-based interface that allows the user to select events with choice of magnitude, distance, and time period. Once the user has selected an event of interest, the ability to view the data is provided, along with some waveform parameters like peak velocity and acceleration. The records can then be downloaded in a number of common formats, including MSEED, SAC, and an ASCII text-based real-time data viewer (RDV) format. The last format allows the data to be viewed in the NEES RDV tool, a platform independent JAVA program developed to display both real-time streaming data, or playback data that has been downloaded through the web-based event search tool.
Steidl, J. H.; Seale, S.; Ratzesberger, H.; Civilini, F.; Vaughan, N.
Utilization of strong motion data for damage assessment of reinforced concrete bridges
NASA Astrophysics Data System (ADS)
This study investigates the performance of a vibration-based technique for damage assessment of reinforced concrete bridges from non-stationary and incomplete acceleration response measurements during high amplitude earthquakes. The proposed damage assessment technique is targeted to be used in the aftermath of a major earthquake event to rapidly and remotely assess the functionality status of the bridge and identify potential hazards to the public safety. As the first step of the procedure, time-frequency representation of the response of the bridge is achieved by applying stochastic subspace system identification technique to successive and overlapping windows of the response measurements. The timefrequency representation is then used to identify the longest ending segment of the response with relatively stable modal properties. Post-earthquake experimental modal properties of the bridge are subsequently extracted from the identified stable portion of the response. These properties are used to estimate the amount of degradation in stiffness of the structural elements through an optimization-based finite element model updating technique. The Genetic Algorithm optimization technique is used to update the stiffness properties of the structural elements by minimizing the error between analytical and experimental modal properties of the bridge. The proposed damage assessment procedure is applied to experimental data from a large-scale shake table test during which a quarter-scale model of a reinforced concrete bridge was subjected to a series of earthquake and low-amplitude white noise base excitations. The meaningful agreement between the stiffness correction factors identified from both types of motions at the same damage state of the bridge demonstrates that the proposed procedure can effectively be applied for post-earthquake damage assessment of the bridges from nonlinear responses during high amplitude earthquakes.
Baghaei, Reza; Feng, Maria Q.
Complexity of the Mw 6.3 2009 L'Aquila (central Italy) earthquake: 2. Broadband strong motion modeling
NASA Astrophysics Data System (ADS)
Near-fault strong-ground motions (0.1-10 Hz) recorded during the Mw 6.3 2009 L'Aquila earthquake exhibit great spatial variability. Modeling the observed seismograms allows linking distinct features of the observed wavefield to particular source and propagation effects and provides insights on strong motion complexity from this moderate magnitude event. We utilize a hybrid integral-composite approach based on a k-square kinematic rupture model, combining low-frequency coherent and high-frequency incoherent source radiation and providing omega-squared source spectral decay. Several source model features, proven to be stable by means of an uncertainty analysis in the preceding low-frequency (<0.2 Hz) multiple finite-extent source inversion (Paper 1), were constrained. Synthetic Green's functions are calculated in a 1D-layered crustal model including 1D soil profiles to account for site-specific response (where available). The results show that although the local site effects improve the modeling, the spatial broadband ground-motion variability is to large extent controlled by the rupture kinematics. The modeling thus confirms and further constraints the source model features, including the position and slip amount of the two main asperities, the largest asperity time delay and the rupture velocity distribution on the fault. Furthermore, we demonstrate that the crossover frequency dividing the coherent and incoherent wavefield, often considered independent on the station position, has to be variable in order to adequately reproduce both near and far station recordings. This suggests that the incoherency of the radiated wavefield is controlled by the wave-propagation phenomena and/or the initial updip rupture propagation was very smooth (coherent) up to relatively high frequencies (>2 Hz).
Ameri, G.; Gallovi?, F.; Pacor, F.
Effects of fault dip and slip rake angles on near-source ground motions: Why rupture directivity was minimal in the 1999 Chi-Chi, Taiwan, earthquake
We study how the fault dip and slip rake angles affect near-source ground velocities and displacements as faulting transitions from strike-slip motion on a vertical fault to thrust motion on a shallow-dipping fault. Ground motions are computed for five fault geometries with different combinations of fault dip and rake angles and common values for the fault area and the average slip. The nature of the shear-wave directivity is the key factor in determining the size and distribution of the peak velocities and displacements. Strong shear-wave directivity requires that (1) the observer is located in the direction of rupture propagation and (2) the rupture propagates parallel to the direction of the fault slip vector. We show that predominantly along-strike rupture of a thrust fault (geometry similar in the Chi-Chi earthquake) minimizes the area subjected to large-amplitude velocity pulses associated with rupture directivity, because the rupture propagates perpendicular to the slip vector; that is, the rupture propagates in the direction of a node in the shear-wave radiation pattern. In our simulations with a shallow hypocenter, the maximum peak-to-peak horizontal velocities exceed 1.5 m/sec over an area of only 200 km2 for the 30??-dipping fault (geometry similar to the Chi-Chi earthquake), whereas for the 60??- and 75??-dipping faults this velocity is exceeded over an area of 2700 km2 . These simulations indicate that the area subjected to large-amplitude long-period ground motions would be larger for events of the same size as Chi-Chi that have different styles of faulting or a deeper hypocenter.
Aagaard, B. T.; Hall, J. F.; Heaton, T. H.
Kinematic inversion of strong motion data using a Gaussian parameterization of the slip: application to the Iwate-Miyagi earthquake.
NASA Astrophysics Data System (ADS)
We present a non linear technique to invert strong motion records with the aim of obtaining the final slip and the rupture velocity distributions on the fault plane. Kinematic inversion of strong motion data is an ill-conditioned inverse problem, with several solutions available also in the case of noise-free synthetic data (Blind test on earthquake source inversion,http://www.seismo.ethz.ch/staff/martin/BlindTest.html).On the other hand, complete dynamic inversion still looks impracticable, because of an unclear understanding of the physical mechanisms controlling the energy balance at the rupture tip and a strong correlation between the initial stress field and the parameters of the constitutive law. Hence a strong effort is demanded to increase the robustness of the inversion, looking at the details of the slip and rupture velocity parameterization, at the global exploration techniques, at the efficiency of the cost-function in selecting solutions, at the synthesis process in retrieving the stable features of the rupture. In this study, the forward problem, i.e. the ground motion simulation, is solved evaluating the representation integral in the frequency domain by allowing possible rake variation along the fault plane. The Green's tractions on the fault are computed using the discrete wave-number integration technique that provides the full wave-field in a 1D layered propagation medium. The representation integral is computed through a finite elements technique on a Delaunay triangulation of the fault plane. The rupture velocity is finally defined on a coarser regular grid and rupture times are computed by integration of the eikonal equation. For the inversion, the slip distribution is parameterized by 2D overlapping Gaussian functions, which can easily relate the spectrum of the possible solutions with the minimum resolvable wavelength, related to source-station distribution and data processing. The inverse problem is solved by a two-step procedure aimed at separating the computation of the rupture velocity from the evaluation of the slip distribution, the latter being a linear problem, when the rupture velocity is fixed. The non-linear step is solved by optimization of an L2 misfit function between synthetic and real seismograms, and solution is searched by the use of the Neighbourhood Algorithm. The conjugate gradient method is used to solve the linear step instead. The developed methodology has been applied to the M7.2, Iwate Nairiku Miyagi, Japan, earthquake that was recorded by the K-net and Kik-net accelerometric networks.
Lucca, Ernestina; Festa, Gaetano; Emolo, Antonio
An initial model of seismic microzonation of Sikkim Himalaya through thematic mapping and GIS integration of geological and strong motion features
Seismic microzonation and hazard mapping was undertaken in the Sikkim Himalaya with local site conditions and strong ground motion attributes incorporated into a geographic information system. A strong motion network in Sikkim consisting of 9 digital accelerographs recorded more than 100 events during 1998�2002, of which 72 events are selected with signal-to-noise ratios ?3 for the estimation of site response
Sankar Kumar Nath
Source Process of the 2003 Bam, Iran, Earthquake inferred from Joint Inversion of Teleseismic and Strong Motion Data
NASA Astrophysics Data System (ADS)
We attempt to determine precise fault geometry and source process of the December 26, 2003 Bam earthquake from southeast Iran, and answer the question why a moderate event (Mw 6.5) resulted in such a large disaster. Previous studies showed that the earthquake was caused by a subsurface rupture on previously unknown strike-slip fault. A remarkable record obtained at the strong-motion station inside the city of Bam and 5 km from the epicenter shows the PGA value of 988 gal in the UD component and two pulses with a dominant frequency of 1 Hz in the horizontal components. It was inferred that the large PGA value recorded at Bam station and the proportion of damage provoked by this event might be explained by the combination of the forward rupture directivity effect towards the city of Bam and a large speed of the rupture front over the fault (Bouchon et al., 2005). Although, there have been proposed several fault models of this event from geodetic data (Talebian et al., 2004; Wang et al., 2004; Fielding et al., 2005) and aftershock analysis (Nakamura et al., 2005), they are varying significantly in there location and some of them propose existence of the fault branching towards the north, beneath the city of Bam. We inverted teleseismic and strong motion data to determine the precise fault configuration and rupture process of the 2003 Bam earthquake. It is expected that the combination of this two different datasets will offer a more stable image of the source area, while each of the teleseismic and strong motion data carries information on different period ranges of the process at the source. To infer the general rupture process, we first analyzed teleseismic dataset. We applied the moment tensor analysis as well as the source inversion method developed by Kikuchi and Kanamori (1982, 1991) and Kikuchi et al. (2003) to 23 P- and 17 SH- far-field displacement waveforms from IRIS-DMC database. The hypocenter location was assumed to be at 29.050N, 58.365E and the initial fault dimensions to be 25 km in length by 20 km in width, as determined from the aftershock distribution (Suzuki et al., 2005). The result of the teleseimsic source inversions shows the slip distribution that confirms a single asperity, as suggested by Yamanaka (2003), with the rupture propagated S-N direction along almost vertical strike-slip fault with the following fault parameters: strike 176�, dip 88�, rake 166�. The hypocentral depth of the best model is estimated to be 8 km. In the next step, using the finite fault parameters resulted from the teleseismic waveform inversion, we applied the inversion method of Yoshida et al. (1996) to strong motion records of BHRC stations from Iran. We used three components of velocity records at BAM, ABR and MOH stations to infer the precise epicenter location and rupture velocity. According to our analysis, a single fault model characterized by the appropriate location of the hypocenter, on the fault plane derived from aftershock distribution by Nakamura et al. (2005), can explain both the directivity and double pulses for three components at Bam station. We used both the ABIC criteria and fitting of observed and synthetic waveforms as the objective judgment of the best model selection. We also determined the rupture velocity that minimizes the residuals between observed and synthetic waveforms to be 2.9 km/s. This agrees with the result of the Rayleigh-like speed of the rupture pointed out by Bouchon et al. (2005). Finally, we performed the joined inversion of the teleseismic and strong motion datasets to obtain a stable source model for the 2003 Bam event. The inversion methods and datasets are the same as in the single dataset analysis. We used the finite fault parameters as determined from the teleseismic waveform inversion and the epicenter location and rupture velocity resulted from strong motion waveform inversion. Our joint inversion result shows that both teleseismic and strong motion datasets can be satisfactory explained by a single fault model with the single asperity located slightly above the hypocente
Poiata, N.; Miyake, H.; Koketsu, K.; Hikima, K.
Preliminary summary of the U.S. Geological Survey strong-motion records from the October 15, 1979 Imperial Valley earthquake
This report summarizes the data from near-in strong-motion accelerograph stations operated by the U.S. Geological Survey in the Imperial Valley of California at the time of the October 15, 1979 Imperial Valley earthquake. The purpose of this report is to alert others as to the nature of the strong-motion data that is available from this event. In order to provide the information in a timely manner, the report has been limited to a summary of the data. A similar preliminary report of strong-motion data collected by the Office of Strong-Motion Studies of the California Division of Mines and Geology has already been issued. A more complete report of all of the strong ground motion data is contemplated. This will require the cooperation of all of the agencies in both the U.S. and Mexico that operate strong-motion instruments in the region. A report on the processing of the data from near-in stations is in preparation. The moderate-size (magnitude 6.4) October 15, 1979 Imperial Valley earthquake was instrumentally located on the Imperial fault approximately 25 km southeast of El Centro, California. This location is approximately the same as that of the 1940 Imperial Valley earthquake.
Porcella, R. L.; Matthiesen, R. B.
An estimation of sediment thickness using Sp converted phases in Kaoping, Taiwan
NASA Astrophysics Data System (ADS)
The Kaoping area is a triangle alluvial plain, located in the southwestern Taiwan. Accelerograms recorded from 1991 to 2010 by the Taiwan Strong Motion Instrumentation Program (TSMIP) stations are used to study the thickness variations of the Quaternary alluviums beneath Kaoping area by examining the Sp converted phase. Travel-time difference of S and Sp phases is used to estimate the sediment thickness. With highly seismicity activities and dense strong motion array, this technique has been used in Lan-Yang Plain and Chia-Nan Plain. In this study we focus on Kaoping region in order to discuss the underground structures in the study region. The major targets are to determine the location of Chaochou fault and Sp phase is converted from which formation boundary. Results show that the thickness become thicker toward the west in Kaohsiung area, and the thickness become thinner toward east. Details will be presented in this study.
Chuang, M.; Wu, Y.; Wei, J.; Chang, C.
ERIC Educational Resources Information Center
This issue of Exploratorium Magazine focuses on the topic of motion. Contents include: (1) "First Word" (Zach Tobias); (2) "Cosmic Collisions" (Robert Irion); (3) "The Mobile Cell" (Karen E. Kalumuck); (4) "The Paths of Paths" (Steven Vogel); (5) "Fragments" (Pearl Tesler); (6) "Moving Pictures" (Amy Snyder); (7) "Plants on the Go" (Katharine�
Brand, Judith, Ed.
We report results of foam-rubber modeling of the effect of a shallow weak layer on ground motion from strike-slip ruptures. Computer modeling of strong ground motion from strike-slip earthquakes has involved somewhat arbitrary assumptions about the nature of slip along the shallow part of the fault (e.g., fixing the slip to be zero along the upper 2 kilometers of the fault plane) in order to match certain strong motion accelerograms. Most modeling studies of earthquake strong ground motion have used what is termed kinematic dislocation modeling. In kinematic modeling the time function for slip on the fault is prescribed, and the response of the layered medium is calculated. Unfortunately, there is no guarantee that the model and the prescribed slip are physically reasonable unless the true nature of the medium and its motions are known ahead of time. There is good reason to believe that in many cases faults are weak along the upper few kilometers of the fault zone and may not be able to maintain high levels of shear strain required for high dynamic energy release during earthquakes. Physical models of faulting, as distinct from numerical or mathematical models, are guaranteed to obey static and dynamic mechanical laws. Foam-rubber modeling studies have been reported in a number of publications. The object of this paper is to present results of physical modeling using a shallow weak layer, in order to verify the physical basis for assuming a long rise time and a reduced high frequency pulse for the slip on the shallow part of faults. It appears a 2-kilometer deep, weak zone along strike-slip faults could indeed reduce the high frequency energy radiated from shallow slip, and that this effect can best be represented by superimposing a small amplitude, short rise-time pulse at the onset of a much longer rise-time slip. A weak zone was modeled by inserting weak plastic layers of a few inches in thickness into the foam rubber model. For the 15 cm weak zone the average pulse is reduced by a factor of 0.46. The factor for the 20 cm case reduction is 0.11. For the 30 cm case it is 0.045. From these results we can see that, the thicker the weak layer, the more difficult it is for a short rise-time acceleration pulse to push its way through the weak layer to the surface. This is thus an approximate justification for reducing the high frequency radiation from shallower parts of strike-slip faults if it is known that the shallow part of the fault is weak or has not stored up shear stress.
Fault location and source process of the 2003 Boumerdes, Algeria, earthquake inferred from geodetic and strong motion data.
NASA Astrophysics Data System (ADS)
The Boumerdes earthquake occurred on a fault which precise location, offshore the algerian coast, was unknown. Geodetic data consist of GPS measurements, levelling points and coastal uplifts. They are first used to determine the absolute position of the fault. We performed a series of inversions assuming different positions and chose the model giving the smallest misfit. According to this analysis, the fault emerge at about 15 km offshore. Accelerograms are then used to infer the space-time history of rupture on the fault plane using a two-step inversion in the spectral domain. The observed strong motion records are in good agreement with the synthetics for the fault location inferred from geodetic data. The fault plane ruptured for about 16 seconds. The slip distribution on the fault indicates one asperity north-west of the hypocenter with a maximum slip amplitude larger than 2.5 m. Another asperity with slightly smaller slip amplitude is located south-east of the hypocenter. The rupture seems to stop its propagation westward when it encounters the Thenia fault, a structure almost perpendicular to the main fault. We computed the spatial distribution of ground motion predicted by this fault model and compared it with the observed damages.
Semmane, F.; Campillo, M.; Cotton, F.
Comments on baseline correction of digital strong-motion data: Examples from the 1999 Hector Mine, California, earthquake
Residual displacements for large earthquakes can sometimes be determined from recordings on modern digital instruments, but baseline offsets of unknown origin make it difficult in many cases to do so. To recover the residual displacement, we suggest tailoring a correction scheme by studying the character of the velocity obtained by integration of zeroth-order-corrected acceleration and then seeing if the residual displacements are stable when the various parameters in the particular correction scheme are varied. For many seismological and engineering purposes, however, the residual displacement are of lesser importance than ground motions at periods less than about 20 sec. These ground motions are often recoverable with simple baseline correction and low-cut filtering. In this largely empirical study, we illustrate the consequences of various correction schemes, drawing primarily from digital recordings of the 1999 Hector Mine, California, earthquake. We show that with simple processing the displacement waveforms for this event are very similar for stations separated by as much as 20 km. We also show that a strong pulse on the transverse component was radiated from the Hector Mine earthquake and propagated with little distortion to distances exceeding 170 km; this pulse leads to large response spectral amplitudes around 10 sec.
Boore, D. M.; Stephens, C. D.; Joyner, W. B.
Seismically induced rock slope failures resulting from topographic amplification of strong ground motions: The case of Pacoima Canyon, California
The 1994 Northridge earthquake (Mw = 6.7) triggered extensive rock slope failures in Pacoima Canyon, immediately north of Los Angeles, California. Pacoima Canyon is a narrow and steep canyon incised in gneissic and granitic rocks. Peak accelerations of nearly 1.6 g were recorded at a ridge that forms the left abutment of Pacoima Dam; peak accelerations at the bottom of the canyon were less than 0.5 g, suggesting the occurrence of topographic amplification. Topographic effects have been previously suggested to explain similarly high ground motions at the site during the 1971 (Mw = 6.7) San Fernando earthquake. Furthermore, high landslide concentrations observed in the area have been attributed to unusually strong ground motions rather than higher susceptibility to sliding compared with nearby zones. We conducted field investigations and slope stability back-analyses to confirm the impact of topographic amplification on the triggering of landslides during the 1994 earthquake. Our results suggest that the observed extensive rock sliding and falling would have not been possible under unamplified seismic conditions, which would have generated a significantly lower number of areas affected by landslides. In contrast, modelling slope stability using amplified ground shaking predicts slope failure distributions matching what occurred in 1994. This observation confirms a significant role for topographic amplification on the triggering of landslides at the site, and emphasises the need to select carefully the inputs for seismic slope stability analyses. ?? 2005 Elsevier B.V. All rights reserved.
Sepulveda, S. A.; Murphy, W.; Jibson, R. W.; Petley, D. N.
Fault location and source process of the Boumerdes, Algeria, earthquake inferred from geodetic and strong motion data
NASA Astrophysics Data System (ADS)
The Boumerdes earthquake occurred on a fault whose precise location, offshore the Algerian coast, was unknown. Geodetic data are used to determine the absolute position of the fault. The fault might emerge at about 15 km offshore. Accelerograms are used to infer the space-time history of the rupture using a two-step inversion in the spectral domain. The observed strong motion records agree with the synthetics for the fault location inferred from geodetic data. The fault plane ruptured for about 18 seconds. The slip distribution on the fault indicates one asperity northwest of the hypocenter with maximum slip amplitude about 3 m. This asperity is probably responsible for most of the damage. Another asperity with slightly smaller slip amplitude is located southeast of the hypocenter. The rupture stops its westward propagation close to the Thenia fault, a structure almost perpendicular to the main fault.
Semmane, Fethi; Campillo, Michel; Cotton, Fabrice
A method for the separation of source and site effects and the apparent Q structure from strong motion data
NASA Astrophysics Data System (ADS)
A new/modified technique for the separation of source, path and site effects from strong motion records is proposed. To do this we made two extensions of the method developed in [Iwata and Irikura, 1988]. (1) We allow the Q-value to be variable with depth and subregion in a block model of the medium with constant Q in each block. Path lengths within blocks are calculated using ray approximation. (2) To estimate the absolute site effect at reference station (and source effects respectively) we can use the H/V spectral ratio method for the S-wave group to determine the spectral correction at the reference station. Our new method was applied to a set of KNET data in the Tohoku area of Japan. Preliminary results of Q structure inversion show that Q has minor variations with depth, and slightly decreases in the deepest layer. Source effects clearly show the existence of fmax phenomena (fmax=13Hz).
Petukhin, Anatoly; Irikura, Kojiro
The design and performance of a low-cost strong-motion sensor using the ICS-3028 micromachined accelerometer
The severity of earthquake ground shaking varies tremendously over very short distances (Figures 1a-c). Within a distance of as little as 1 km from the nearest station, one knows little more than what can be obtained from an attenuation relation, given only distance from the fault rupture and the geology of the site. For example, if some station measures 0.5 g peak ground acceleration (PGA), then at a distance of 1 km from that site, under otherwise identical conditions, the shaking has one chance in three of being under 0.36 g or over 0.70 g, based on the curve shown in Figures la, c. Similarly, pseudovelocity (PSV) response spectra have a 5% chance of differing by 2? at 1 km distance (Figure 1 b). This variance can be the difference between moderate and severe damage. Hence, there are critical needs, both in emergency response and in mitigation (prediction of shaking strength, building codes, structural engineering), to sample ground shaking densely enough to identify individual neighborhoods suffering localized, strong shaking. These needs imply a spatially dense network of strong-motion seismographs, probably numbering thousands of sites in an urban region the size of the San Francisco Bay Area, California (Figure 1 c). It has not been economically feasible to field that many instruments, since existing ones cost many thousands of dollars apiece. For example, there are currently just a few dozen digital free-field instruments in the Bay Area. This paper is one step toward a solution to this conundrum. I demonstrate that a recently developed class of accelerometers, those constructed from silicon by 'micromachining' (a process similar to integrated circuit fabrication), is now capable of resolving ground motion with the necessary accuracy while greatly lowering both acquisition and maintenance costs.
Evans, J. R.
Consistency of GPS and strong-motion records: case study of the Mw9.0 Tohoku-Oki 2011 earthquake
NASA Astrophysics Data System (ADS)
High-rate GPS data are today commonly used to supplement seismic data for the Earth surface motions focusing on earthquake characterisation and rupture modelling. Processing of GPS records using Precise Point Positioning (PPP) can provide real-time information of seismic wave propagation, tsunami early-warning and seismic rupture. Most studies have shown differences between the GPS and seismic systems at very long periods (e.g. >100sec) and static displacements. The aim of this study is the assessment of the consistency of GPS and strong-motion records by comparing their respective displacement waveforms for several frequency bands. For this purpose, the records of the GPS (GEONET) and the strong-motion (KiK-net and K-NET) networks corresponding to the Mw9.0 Tohoku 2011 earthquake were analysed. The comparison of the displacement waveforms of collocated (distance<100m) GPS and strong-motion sites show that the consistency between the two datasets depends on the frequency of the excitation. Differences are mainly due to the GPS noise at relatively short-periods (<3-4 s) and the saturation of the strong-motion sensors for relatively long-periods (40-80 s). Furthermore the agreement between the GPS and strong-motion records also depends on the direction of the excitation signal and the distance from the epicentre. In conclusion, velocities and displacements recovered from GPS and strong-motion records are consistent for long-periods (3-100 s), proving that GPS networks can contribute to the real-time estimation of the long-period ground motion map of an earthquake.
Psimoulis, Panos; Houli�, Nicolas; Michel, Clotaire; Meindl, Michael; Rothacher, Markus
The successes and failures of a key transportation link: accessibility effects of Taiwan�s high-speed rail
Taiwan does not only have a high population density; its population exhibits a strong preference for high-density downtown\\u000a living. Rich Taiwanese thus live downtown, not in the suburbs. In addition, the expected negative relationship between accessibility\\u000a and the spaciousness of housing is weak or non-existent in Taiwan�s metropolitan areas. Taiwan should therefore be highly\\u000a suited to rail transportation investments. In
David Emanuel Andersson; Oliver F. Shyr; Angel Lee
Source parameters of the 2013 Lushan, Sichuan, Ms7.0 earthquake and estimation of the near-fault strong ground motion
NASA Astrophysics Data System (ADS)
Abstract: The April 20, 2013 Ms 7.0 earthquake in Lushan city, Sichuan province of China occurred as the result of east-west oriented reverse-type motion on a north-south striking fault. The source location suggests the event occurred on the Southern part of Longmenshan fault at a depth of 13km. The Lushan earthquake caused a great of loss of property and 196 deaths. The maximum intensity is up to VIII to IX at Boxing and Lushan city, which are located in the meizoseismal area. In this study, we analyzed the dynamic source process and calculated source spectral parameters, estimated the strong ground motion in the near-fault field based on the Brune's circle model at first. A dynamical composite source model (DCSM) has been developed further to simulate the near-fault strong ground motion with associated fault rupture properties at Boxing and Lushan city, respectively. The results indicate that the frictional undershoot behavior in the dynamic source process of Lushan earthquake, which is actually different from the overshoot activity of the Wenchuan earthquake. Based on the simulated results of the near-fault strong ground motion, described the intensity distribution of the Lushan earthquake field. The simulated intensity indicated that, the maximum intensity value is IX, and region with and above VII almost 16,000km2, which is consistence with observation intensity published online by China Earthquake Administration (CEA) on April 25. Moreover, the numerical modeling developed in this study has great application in the strong ground motion prediction and intensity estimation for the earthquake rescue purpose. In fact, the estimation methods based on the empirical relationship and numerical modeling developed in this study has great application in the strong ground motion prediction for the earthquake source process understand purpose. Keywords: Lushan, Ms7.0 earthquake; near-fault strong ground motion; DCSM; simulated intensity
Meng, L.; Zhou, L.; Liu, J.
H/V ratio in Athens and the strong motion at the Ano Liosia site during the 1999 Athens earthquake
NASA Astrophysics Data System (ADS)
The damaging 1999 Athens earthquake of Mw=5.9 occurred at about 20km from the city center. The intensity distribution in the capital, ranging from V to IX, was quite irregular due to combination of the source, path and site effects. The 30-stations temporary network of the University of Patras, installed in the area of Attica for 50 days, recorded a significant part of the aftershock sequence. The aftershocks not only delineated the mainshock fault plane, but they also provided important site classification. The Horizontal-to-Vertical spectral ratio method was applied, and the most significant amplification (H/V exceeding 4 in the frequency range 1-4Hz) was found at the Ano Liosia site, belonging to the most heavily damaged zones with intensity IX. The site is situated in a shallow basin, whose surface extent is about 4x4 km, and the maximum depth is of about 150 m. Based on geological and geophysical data (Vp, Vs, Q) measured at the site, the numerical modeling of the seismic site response was carried out. The finite-differences technique was used for a 2D modeling, and significant edge effects were revealed, e.g. the amplification by a factor of 3, with respect to the outcropping bedrock. The 1D effects of the sediment layering, modeled by the matrix technique, would produce much weaker amplification, and simpler time history of the response. No recording of the mainshock is available from Ano Liosia. Nevertheless, based on the finite-extent source model validated by the existing strong motion records in Athens, we assume that the bedrock motion in Ano Liosia had its PGA ranging from 0.2 to 0.3 g, resulting from the relatively small epicentral distance (~ 10 km) and the forward source directivity (Serpetsidaki et al., session SM10). When combined with the above discussed site effect, the PGA values in Ano Liosia might locally exceed 0.6g.
Serpetsidaki, A.; Tselentis, G.-A.; Zahradnik, J.
Determination of site amplification in the Los Angeles urban area from inversion of strong-motion records
The amplification of strong ground motion at sites in the greater Los Angeles, California, region is determined using the generalized-inverse method of Andrews (1986). Site-amplification estimates are determined at 281 strong-motion sites that provided horizontal-component accelerograms from the 1971 San Fernando, 1987 Whittier Narrows, 1991 Sierra Madre, or 1994 Northridge mainshocks. The estimates are determined relative to the spectral level recorded at a single reference site. In a second inversion, a source-site interaction term is added to Andrews's (1986) model to quantify the effect selected mainshock records have on site-amplification estimates. The source-site interaction term is applied to the San Fernando Valley sites' records of the Northridge earthquake and to three Los Angeles basin sites' records of the Whittier Narrows mainshock. Site-amplification spectra are averaged within two frequency bands: the intermediate-frequency band (IFB) from 0.5 to 1.5 Hz and the high-frequency band (HFB) from 2 to 6 Hz. Results are displayed on maps of surficial geology. Average spectral levels are correlated with average shear-wave velocity in the uppermost 30 m, a geotechnical parameter used by the National Earthquake Hazards Reduction Program (NEHRP) to characterize site amplification. Statistically significant correlation is found in both frequency bands. Average spectral amplification levels for NEHRP class B, C, and D sites in the LA urban area are determined. These averages display an expected increase in spectral amplification with category, with a more pronounced variation in the IFB than in the HFB. Considerable overlap in the one-standard-deviation range of the C and D site levels is found in both IFB and HFB, suggesting that site-specific spectral amplification is influenced by more than just near-surface shear-wave velocity. Average site-amplification levels are compared with those obtained from Northridge aftershock records at 28 collocated sites and are found to be in reasonably good agreement in both frequency bands. Some interesting outliers, that is, sites for which the mainshock- and aftershock-determined amplifications differ significantly, are identified as sites that experienced ground failure during the Northridge mainshock.
Harmsen, S. C.
Rupture Process of the March 2011 Tohoku-Oki Earthquake from Back-Projection of Local Strong-Motion Records
NASA Astrophysics Data System (ADS)
The Mw 9.0 megathrust earthquake off northeastern Honshu, Japan, in March 2011 had an unexpected size for a region which experienced only few events with magnitude larger than 8.0 in the past millennium. The event originated at crustal depths along a segment of the Pacific slab of the Japanese subduction zone. Large slip deficit and strong interplate coupling have been previously detected there by inland deformation measurements. The pattern of seismicity occurrence and the mechanical coupling between the different sectors of the Japan slab suggest that its morphology and segmentation may be strongly influenced by the presence of landward oceanic fracture zones. The aim of this study is to image the locations of strongly radiating sources and the rupture development during the faulting process. We used strong-motion records from the dense Japanese accelerometer arrays, integrated twice to obtain ground displacement, and filtered in different frequency bands between 0.04 Hz and 2.0 Hz. We applied a move-out and stacking technique to back-project the S-wave displacement amplitudes onto the subducting plate boundary, including the proper correction for geometrical spreading and source radiation pattern. Thus, the resulting images are consistently mapped into the slip distribution during the rupture development. Image resolution and sensitivity to processing parameters is assessed by synthetic tests. Our results show that the great Tohoku earthquake started as a smaller size rupture, slowly propagating upward along the slab segment and triggering the break of a larger size asperity at shallower depths near the trench. In that region also the largest slip has been observed in various studies. For a large amount of its duration, the rupture remained confined in a 100-150 km wide slab stripe, delimited by two Northwest-Southeast trending oceanic fractures. After about a minute, the rupture propagated at relatively high speed toward Southwest, parallel to the trench. The occurrence of large slip amplitudes at shallow depths likely favored the rupture to propagate across contiguous slab segments and contributed to build up a giant size earthquake. The lateral variations in the slab surface geometry may act as geometrical and/or mechanical barriers finally controlling the earthquake rupture nucleation, evolution and arrest.
Maercklin, N.; Festa, G.; Colombelli, S.; Zollo, A.
Combining Broadband, Strong Motion, and other geophysical data in real time data acquisition and processing at the Swiss Seismological Service SED
NASA Astrophysics Data System (ADS)
The Swiss Seismological Service (SED) operates one of the densest seismic broadband networks in Europe with 27 STS2 stations transmitting 24 bit 120sps data in real time. In addition the SED operates a network of 77 strong-motion recorders (65 free-field, 12 on hard rock co-located with broadband sensors). At 16 of the free-field sites and the 12 hard-rock sites Episensor accelerometers and 24 bit digitizers are installed and data is also transmitted in real time, while the other stations are equipped with 1990-era Geosig strong motion sensors, 16 bit A/D converters, and dial-up telephone links. Over the next 10years it is planned to replace those older strong motion stations with Episensors, 24 bit digitizers, and real-time data links, and to install an additional 51 free-field stations of that type. Past experience has shown that the strong motion data is very useful for refining the hypocentral parameters especially for smaller earthquakes, so in future all new strong motion channels will be integrated into the real-time processing.According to the SED open data policy all this data will be freely available e.g. through ORFEUS. Furthermore, new regional experiments in Switzerland (in particular COGEAR, "Coupled seismogenic Geohazards in Alpine Regions") will provide additional data from dense temporary deployments of strong motion stations and real-time GPS, but also from other geophysical methods like geochemical and magnetotelluric measurements with significantly different data types and sampling rates. Apart from the challenges of integrated acquisition and quasi-real-time processing of all that data the provision of efficient access to data streams and station metadata requires new concepts of web-based data visualisation and retrieval implementations (e.g. webmap services).
Clinton, J.; Haslinger, F.; F�h, D.; Zweifel, P.; Schnabel, O.; Giardini, D.
A teleseismic study of the 2002 Denali fault, Alaska, earthquake and implications for rapid strong-motion estimation
Slip histories for the 2002 M7.9 Denali fault, Alaska, earthquake are derived rapidly from global teleseismic waveform data. In phases, three models improve matching waveform data and recovery of rupture details. In the first model (Phase I), analogous to an automated solution, a simple fault plane is fixed based on the preliminary Harvard Centroid Moment Tensor mechanism and the epicenter provided by the Preliminary Determination of Epicenters. This model is then updated (Phase II) by implementing a more realistic fault geometry inferred from Digital Elevation Model topography and further (Phase III) by using the calibrated P-wave and SH-wave arrival times derived from modeling of the nearby 2002 M6.7 Nenana Mountain earthquake. These models are used to predict the peak ground velocity and the shaking intensity field in the fault vicinity. The procedure to estimate local strong motion could be automated and used for global real-time earthquake shaking and damage assessment. ?? 2004, Earthquake Engineering Research Institute.
Ji, C.; Helmberger, D. V.; Wald, D. J.
Robust features of the source process for the 2004 Parkfield, California, earthquake from strong-motion seismograms
NASA Astrophysics Data System (ADS)
We explore a recently developed procedure for kinematic inversion based on an elliptical subfault approximation. In this method, the slip is modelled by a small set of elliptical patches, each ellipse having a Gaussian distribution of slip. We invert near-field strong ground motion for the 2004 September 28 Mw 6.0 Parkfield, California, earthquake. The data set consists of 10 digital three-component 18-s long displacement seismograms. The best model gives a moment of 1.21 � 1018 N m, with slip on two distinct ellipses, one with a high-slip amplitude of 0.91 m located 20 km northwest of the hypocentre. The average rupture speed of the rupture process is �2.7 km s-1. We find no slip in the top 5 km. At this depth, a lineation of small aftershocks marks the transition from creeping above to locked below, in the interseismic period. The high-slip patch coincides spatially with the hypocentre of the 1966 Mw6.0 Parkfield, California, earthquake. The larger earthquakes prior to the 2004 Parkfield earthquake and the aftershocks of the 2004 earthquake (Mw > 3) also lie around this high-slip patch, where our model images a sharp slip gradient. This observation suggests the presence of a permanent asperity that breaks during large earthquakes, and has important implications for the slip deficit observed on the Parkfield segment, which is necessary for reliable seismic hazard assessment.
Twardzik, C.; Madariaga, R.; Das, S.; Cust�dio, S.
Calibration of Subsurface Amplification Factors Using Surface/Borehole Strong-motion Records from the KiK-net
NASA Astrophysics Data System (ADS)
The Real-time Earthquake Information System (REIS, Horiuchi et al., 2005) detects earthquakes and determines event parameters using the Hi-net (High-sensitivity seismograph network Japan) data in Japan. The system also predicts the arrival time and seismic intensity at a given site before ground motions arrive. Here, the seismic intensity is estimated based on the intensity magnitude which is derived from data of the Hi-net. As the Hi-net stations are located in the boreholes, intensity estimation on the ground surface is evaluated using a constant for subsurface amplification. But the estimated intensities based on the conventionally used amplification constants are not always in agreement with those observed at specific sites on the ground surface. The KiK-net (KIBAN Kyoshin network Japan) consists of strong motion instruments. Each station has two sets of accelerometers, one set is installed on the ground surface and the other one is co-located with a Hi-net station in the borehole. We use data recorded at the KiK-net stations to calibrate subsurface site amplification factors between the borehole and the ground surface. We selected data recorded for over 200 events during the period of 1997 to 2006 in Hiroshima prefecture and calculated the ratios of peak velocity amplitudes on the ground surface ( Asurf) to those in the borehole ( Abor). The subsurface amplification varies from station to station showing dependency on the propagation distance as well as on the incident direction of seismic waves. Results suggest that the site amplification factors shall be described as a function of distance and incident direction, and are not constants. Thus, we derived empirical amplification formulas between Asurf and the peak velocity amplitudes on the engineering bedrock ( Abed) as a function of distance in place of the conventionally used amplification constants. Here, the engineering bedrock is defined as the depth where the S- wave velocity is 600 m/s. The estimated intensities show substantial improvement in the accuracy at most stations as compared with those calculated using conventional constants. When the amplification dependence on the incident direction was accounted for, the estimated intensities somewhat improved. This calibration will help an earthquake early warning system such as REIS provide more accurate intensity estimates.
Hayashida, T.; Tajima, F.
Application of a net-based baseline correction scheme to strong-motion records of the 2011 Mw 9.0 Tohoku earthquake
NASA Astrophysics Data System (ADS)
The description of static displacements associated with earthquakes is traditionally achieved using GPS, EDM or InSAR data. In addition, displacement histories can be derived from strong-motion records, allowing an improvement of geodetic networks at a high sampling rate and a better physical understanding of earthquake processes. Strong-motion records require a correction procedure appropriate for baseline shifts that may be caused by rotational motion, tilting and other instrumental effects. Common methods use an empirical bilinear correction on the velocity seismograms integrated from the strong-motion records. In this study, we overcome the weaknesses of an empirically based bilinear baseline correction scheme by using a net-based criterion to select the timing parameters. This idea is based on the physical principle that low-frequency seismic waveforms at neighbouring stations are coherent if the interstation distance is much smaller than the distance to the seismic source. For a dense strong-motion network, it is plausible to select the timing parameters so that the correlation coefficient between the velocity seismograms of two neighbouring stations is maximized after the baseline correction. We applied this new concept to the KiK-Net and K-Net strong-motion data available for the 2011 Mw 9.0 Tohoku earthquake. We compared the derived coseismic static displacement with high-quality GPS data, and with the results obtained using empirical methods. The results show that the proposed net-based approach is feasible and more robust than the individual empirical approaches. The outliers caused by unknown problems in the measurement system can be easily detected and quantified.
Tu, Rui; Wang, Rongjiang; Zhang, Yong; Walter, Thomas R.
Joint inversion of strong motion, teleseismic, geodetic, and tsunami datasets for the rupture process of the 2011 Tohoku earthquake
NASA Astrophysics Data System (ADS)
The 2011 Tohoku earthquake of magnitude 9.0 occurred at 5:46 a.m. on March 11, 2011 (UTC), on the megathrust where the Pacific Plate is subducting below Japan. This earthquake was observed by dense networks of strong motion, teleseismic, geodetic, and tsunami sensors; hence, four types of abundant datasets were produced. Various source models were inferred using one of these datasets [e.g., Ide et al., 2011; Simons et al., 2011; Yoshida et al., 2011; Ozawa et al., 2011; Fujii et al., 2011]. However, these models have somewhat different features from each other because of the limitations peculiar to each dataset. In this study, in order to overcome the differences in each case, a quadruple joint inversion of these datasets was carried out to obtain a final solution. The fault model with a strike of 200� having dimensions of 480 � 180 km2 was used. This model was divided into 96 subfaults of 30 � 30 km2. The dips of these subfaults were set to 20�, 12�, and 5� in every two rows from the relatively deep part. Firstly, we performed a separate inversion of each single dataset using the method of Yoshida et al. [1996] with the revisions of Hikima and Koketsu [2005], and examined the resolution of each single dataset by means of a checkerboard test. For the inversion of the strong motion dataset, Green's functions were calculated using the method of Kohketsu [1985]. We selected 20 K-NET and KiK-net stations. For the inversion of the teleseismic dataset, Green's functions were calculated using the method of Kikuchi and Kanamori [1991]. We selected 45 GSN stations. For the inversion of the geodetic dataset, Green's functions were calculated using the method of Zhu and Rivera [2002]. We used 343 GEONET stations and the seafloor data observed by Sato et al. [2011]. For the inversion of the tsunami dataset, Green's functions were calculated using the method of Fujii and Satake [2007]. We selected the 33 stations. These separate inversion results revealed different source models owing to the limited resolution of each single dataset. In order to overcome differences in these results, we performed a quadruple joint inversion of all datasets. In the obtained source model, the maximum coseismic slip is about 35 m and the total seismic moment was calculated to be 4.2 � 1022 Nm, which yields Mw = 9.0. This result revealed that the main rupture was located around the hypocenter. This rupture propagated not only in the strike direction but also in the dip direction and included both the deep area called the Miyagi-oki region and the compact shallow area near the Japan Trench. This compact shallow area is located within the tsunamigenic slip zone of Koketsu et al. [2011], but our result indicates the rupture there to be a usual fault slip.
Yokota, Y.; Koketsu, K.; Fujii, Y.; Satake, K.; Sakai, S.; Shinohara, M.; Kanazawa, T.
The July 12, 1993, Hokkaido-Nansei-Oki, Japan, earthquake: Coseismic slip pattern from strong-motion and teleseismic recordings
We employ a finite fault inversion scheme to infer the distribution of coseismic slip for the July 12, 1993, Hokkaido-Nansei-Oki earthquake using strong ground motions recorded by the Japan Meteorological Agency within 400 km of the epicenter and vertical P waveforms recorded by the Global Digital Seismograph Network at teleseismic distances. The assumed fault geometry is based on the location of the aftershock zone and comprises two fault segments with different orientations: a northern segment striking at N20??E with a 30?? dip to the west and a southern segment with a N20??W strike. For the southern segment we use both westerly and easterly dip directions to test thrust orientations previously proposed for this portion of the fault. The variance reduction is greater using a shallow west dipping segment, suggesting that the direction of dip did not change as the rupture propagated south from the hypocenter. This indicates that the earthquake resulted from the shallow underthrusting of Hokkaido beneath the Sea of Japan. Static vertical movements predicted by the corresponding distribution of fault slip are consistent with the general pattern of surface deformation observed following the earthquake. Fault rupture in the northern segment accounts for about 60% of the total P wave seismic moment of 3.4 ?? 1020 N m and includes a large circular slip zone (4-m peak) near the earthquake hypocenter at depths between 10 and 25 km. Slip in the southern segment is also predominantly shallower than 25 km, but the maximum coseismic displacements (2.0-2.5 m) are observed at a depth of about 5 km. This significant shallow slip in the southern portion of the rupture zone may have been responsible for the large tsunami that devastated the small offshore island of Okushiri. Localized shallow faulting near the island, however, may require a steep westerly dip to reconcile the measured values of ground subsidence.
Mendoza, C.; Fukuyama, E.
High-frequency source imaging of the 2011 October 23 Van (Eastern Turkey) earthquake by backprojection of strong motion waveforms
NASA Astrophysics Data System (ADS)
We backproject strong motion waveforms to image the rupture process of the 2011 October 23 Van (Mw 7.1) earthquake. We show that the followed backprojection approach is applicable for studying earthquake sources with a complex and uncertain fault geometry. It is especially suitable for cases where the implementation of conventional source inversion methods is difficult due to incomplete data coverage from local networks. Normalized high frequency (HF, 2-8 Hz) S-waveform envelopes from recordings on local Turkish and Iranian stations are used to scan a pre-defined 3-D source volume over time. The envelopes are forced to focus at the hypocentre by applying the appropriate station corrections, estimated from waveform cross-correlation. We image two distinct sources of HF radiation during the earthquake rupture at depths between 10 and 12 km. The first one, a few seconds after the rupture initiation, is located near the hypocentre. The second, at least 13 km southwestwards, follows 3.5 s later. While a continuous rupture propagation is not clearly imaged, the average rupture speed is 3.5 km s-1. Synthetic tests show that both HF sources could be resolved adequately from this station distribution. Both sources of HF are located at the edge of large slip patches, imaged by seismic and geodetic inversions. The existence of a complex fault geometry, like a pair of en-echelon reverse faults, explains the radiation of HF energy. The first source is attributed to a stopping phase of the eastern subfault or a possible change on a single fault geometry. The second HF source is produced from the abrupt cease of rupture at the shallow part of the upper crust.
Evangelidis, C. P.; Kao, H.
Survey of strong motion earthquake effects on thermal power plants in California with emphasis on piping systems. Volume 1, Main report
Since 1982, there has been a major effort expended to evaluate the susceptibility of nuclear Power plant equipment to failure and significant damage during seismic events. This was done by making use of data on the performance of electrical and mechanical equipment in conventional power plants and other similar industrial facilities during strong motion earthquakes. This report is intended as
Analysis of landslide damage caused by the 2008 Wenchuan earthquake using strong motion data: A case study in the Beichuan county town
NASA Astrophysics Data System (ADS)
The county town of Beichuan county, China, experienced catastrophic destruction due to landslides induce by the 2008 Wenchuan earthquake. In consideration of the special location of the county town, this paper selected the landslides induced in the town as representative of large-scale near-rupture landslides, and quantitatively analyzed why the landslide damage was so destructive in the town by using strong motion data obtained from the Wenchuan earthquake in the Longmenshan area. Three methods were employed to estimate the landslide damage using strong motion data. (1) Peak ground accelerations (PGAs) on the hanging wall were used to evaluate the PGAs on the landslide sites in the town. The evaluated average PGAs were all greater than 1 g, indicating that the ground motion intensity was very strong during the earthquake. (2) Acceleration time histories, from another station with similar geological conditions to the town, were used to evaluate the critical acceleration changing range, and the estimated values showed the geological conditions were very susceptible to earthquakes. (3) Acceleration time histories, from two stations on the hanging and foot walls of the rupture, and near the town, were used to calculate the Newmark displacements, and all the evaluated displacements indicated that landslides were very likely. The results show that the slopes, susceptible to earthquakes in the Beichuan county town, were easily triggered under such strong ground-motion intensity and developed into large-scale catastrophic events.
Wang, Xiuying; Nie, Gaozhong; Wang, Song
Lessons from the 2003 Tokachi-oki, Japan, earthquake for prediction of long-period strong ground motions and sloshing damage to oil storage tanks
NASA Astrophysics Data System (ADS)
The 2003 Tokachi-oki earthquake ( M w 8.0) in northern Japan generated large-amplitude long-period (4 8 s) ground motions in the Yufutsu sedimentary basin, causing severe damage to seven large oil storage tanks with floating roof structures because of severe sloshing of oil. The 30,000 40,000-m3 tanks having suffered the severe damage such as fires and sinking of floating roofs experienced the sloshing with large amplitudes exceeding 3 m in which the fundamental mode was predominant. The second mode of sloshing was also excited in the 110,000-m3 tanks in which their floating roofs sank into oil, indicating that the higher modes of sloshing as well as the fundamental mode should be considered in damage prediction. The strong ground motion recordings demonstrated the earthquake dependency of predominant periods and the substantial spatial variation of the long-period shaking observed within the Yufutsu basin, meaning the necessity of source- and site-specific prediction of long-period strong ground motions. The two-dimensional numerical modeling suggested the importance of detailed structures of soft near-surface sediments as well as deep basin structure for accurate prediction of long-period strong ground motions in deep sedimentary basins.
Hatayama, Ken
The Seismic Strong Motion Array Project (SSMAP) and the September 5, 2012 Mw=7.6 Nicoya, Costa Rica Earthquake
NASA Astrophysics Data System (ADS)
Seismic gaps along the subduction zones are locations where large earthquakes have not occurred in a long time. The Cocos plate is subducting beneath the Caribbean plate in Costa Rica, and the Nicoya Peninsula, located in northwestern Costa Rica, has been identified as a seismic gap. The previous major earthquakes in Nicoya occurred on 1853, 1900 and 1950, which indicates about a 50-year recurrence interval for the characteristic earthquake cycle. Since 2006, the seismic strong motion array project (SSMAP) for the Nicoya Peninsula in northwestern Costa Rica has been composed of 10 sites with Geotech A900/A800 accelerographs (three-component) and GPS timing. Our digital accelerographs array has been deployed as part of our ongoing research on large earthquakes, including the potential Nicoya event, in conjunction with the Earthquake and Volcano Observatory (OVSICORI) at the Universidad Nacional in Costa Rica. From 2006 to 2012, 28 events were relocated using the SSMAP and OVSICORI data with moderate magnitudes (4 < Mw< 6.5), and were mainly located in Nicoya Peninsula region. On September 5, 2012, a Mw=7.6 earthquake occurred in the seismic gap and appears to be the expected event based on the 50 years recurrence interval, but was instead 62 years later. The main shock focal mechanism was thrust faulting, propagating downdip, of the Cocos plate in the Middle America trench with strike N54W and dip 20 degrees NE. The mainshock and 15 early aftershocks were relocated by using SSMAP, OVSICORI, and UCSC networks. The final location of the mainshock is 9.671 N and 85.878 W with a depth of 18 km. The maximum accelerations from two A900 stations perpendicular to the trench, Fortuna (distance 112km) and Pedernal (distance 128 km) are: 13.8% and 8.9 % g, respectively. In addition, the October 10 (MW 5.3) and 24(Mw 6.6) aftershocks recorded at Tamarindo (distances 40 km and 70 km, respectively) showed accelerations of 2.4% and 8.2% g; respectively. The mainshock acceleration data from SSMAP, University of Costa Rica, and National Electricity Institute networks were analyzed for a new attenuation relationship: Acceleration = -203 ln(R) + 1110 with M=7.6 and R = hypocentral distance.
Simila, Gerald; Mohammadebrahim, Ehsan; McNally, Karen; Quintero, Ronnie; Segura, Juan
Some Key Features of the Strong-Motion Data from the M 6.0 Parkfield, California, Earthquake of 28 September 2004
The 2004 Parkfield, California, earthquake was recorded by an extensive set of strong-motion instruments well positioned to record details of the motion in the near-fault region, where there has previously been very little recorded data. The strong-motion measurements obtained are highly varied, with significant variations occurring over only a few kilometers. The peak accelerations in the near fault region range from 0.13g to over 1.8g (one of the highest acceleration recorded to date, exceeding the capacity of the recording instrument The largest accelerations occurred near the northwest end of the inferred rupture zone. These motions are consistent with directivity for a fault rupturing from the hypocenter near Gold Hill toward the northwest. However, accelerations up to 0.8g were also observed in the opposite direction, at the south end of the Cholame Valley near Highway 41, consistent with bilateral rupture, with rupture southeast of the hypocenter. Several stations near and over the rupturing fault recorded relatively weak motions, consistent with seemingly paradoxical observations of low shaking damage near strike-slip faults. This event had more ground-motion observations within 10 km of the fault than many other earthquakes combined. At moderate distances peak horizontal ground acceleration (PGA) values dropped off more rapidly with distance than standard relationships. At close-in distance the wide variation of PGA suggests a distance-dependent sigma may be important to consider. The near-fault ground-motion variation is greater than that assumed in ShakeMap interpolations, based on the existing set of observed data. Higher density of stations near faults may be the only means in the near future to reduce uncertainty in the interpolations. Outside of the near-fault zone the variance is closer to that assumed. This set of data provides the first case where near-fault radiation has been observed at an adequate number of stations around the fault to allow detailed study of the fault-normal and fault-parallel motion and the near-field S-wave radiation. The fault-normal motions are significant, but they are not large at the central part of the fault, away from the ends. The fault-normal and fault-parallel motions drop off quite rapidly with distance from the fault. Analysis of directivity indicates increased values of peak velocity in the rupture direction. No such dependence is observed in the peak acceleration, except for stations close to the strike of the fault near and beyond the ends of the faulting.
Shakal, A.; Haddadi, H.; Graizer, V.; Lin, K.; Huang, M.
Evaluation of Relative Site Amplification Factors by Combining Average Spectral Ratios of Strong Ground Motions Simultaneously Observed at Adjacent Two Sites
NASA Astrophysics Data System (ADS)
A new method to evaluate relative site amplification factors (RSF) of strong motion sites scattered in a wide area without assumption of attenuation functions is proposed. In this method RSF between adjacent two sites is evaluated by average spectral ratio of strong ground motions simultaneously observed at those two sites. RSF of distant sites are estimated by least squares method, combining RSF of adjacent sites in the network consists of adjacent site pairs in the area. This method is applied to K-NET and KiK-net sites in the Pacific coast side of Tohoku district. Evaluated RSF between adjacent sites are interpreted by theoretical amplification factors based on one dimensional wave theory. Relations of the evaluated RSF with geological condition, and with those estimated by spectral inversion analysis are discussed.
Ikeura, Tomonori; Kato, Kenichi
Application of bounding spectra to seismic design of piping based on the performance of above ground piping in power plants subjected to strong motion earthquakes
This report extends the potential application of Bounding Spectra evaluation procedures, developed as part of the A-46 Unresolved Safety Issue applicable to seismic verification of in-situ electrical and mechanical equipment, to in-situ safety related piping in nuclear power plants. The report presents a summary of earthquake experience data which define the behavior of typical U.S. power plant piping subject to strong motion earthquakes. The report defines those piping system caveats which would assure the seismic adequacy of the piping systems which meet those caveats and whose seismic demand are within the bounding spectra input. Based on the observed behavior of piping in strong motion earthquakes, the report describes the capabilities of the piping system to carry seismic loads as a function of the type of connection (i.e. threaded versus welded). This report also discusses in some detail the basic causes and mechanisms for earthquake damages and failures to power plant piping systems.
Stevenson, J.D. [Stevenson and Associates, Cleveland, OH (United States)
Preliminary determination of the interdependence among strong-motion amplitude, earthquake magnitude and hypocentral distance for the Himalayan region
NASA Astrophysics Data System (ADS)
Since the installation of three limited-aperture strong-motion networks in the Himalayan region in 1986, six earthquakes with Mw=5.2-7.2 have been recorded up to 1991. The data set of horizontal peak accelerations and velocities consists of 182-component data for the hypocentral distance range 10-400km. This data set is limited in volume and coverage and, worst of all, it is highly inhomogeneous. Thus, we could not determine regional trends for amplitudes by means of the traditional approach of empirical multiple regression. Instead, we perform the reduction of the observations to a fixed distance and magnitude using independently defined distance and magnitude trends. To determine an appropriate magnitude-dependent distance attenuation law, we use the spectral energy propagation/random function approach of Gusev (1983) and adjust its parameters based on the residual variance. In doing so we confirm the known, rather gradual mode of decay of amplitudes with distance in the Himalayas; this seems to be caused by the combination of high Qs and crustal waveguide effects for high frequencies. The data are then reduced with respect to magnitude. The trend of peak acceleration versus magnitude cannot be determined from observations, and we assume that it coincides with that of abundant Japanese data. For the resulting set of reduced log10 (peak acceleration) data, the residual variance is 0.372, much above commonly found values. However, dividing the data into two geographical groups, western with two events and eastern with four events, reduces the residual variance to a more usual level of 0.272 (a station/site component of 0.222 and an event component of 0.162). This kind of data description is considered acceptable. A similar analysis is performed with velocity data, and again we have to split the data into two subregional groups. With our theoretically grounded attenuation laws we attempt a tentative extrapolation of our results to small distances and large magnitudes. Our minimum estimates of peak acceleration for the epicentral zone of Mw=7.5-8.5 events is Apeak=0.25-0.4g for the western Himalayas, and as large as Apeak=1-1.6g for the eastern Himalayas. Similarly, the expected minimum epicentral values of Vpeak for Mw=8 are 35cms-1 for the western and 112cms-1 for the eastern Himalayas. To understand whether our results reflect the properties of the subregions and not of a small data set, we check them against macroseismic intensity data for the same subregion. The presence of unusually high levels of epicentral amplitudes for the eastern subregion agrees well with the macroseismic evidence such as the epicentral intensity levels of X-XII for the Great Assam earthquake of 1897. Therefore, our results represent systematic regional effects, and they may be considered as a basis for future regionalized seismic hazard assessment in the Himalayan region. We see the location of earthquake sources/faults at a considerable depth within the relatively drier and higher-strength shield crust as the main cause of the observed enhanced amplitudes for the eastern Himalayas events. Western Himalayas sources are shallower and occupy the tectonically highly fractured upper part of the crust, of accretionary origin. The low attenuation common to both subregions is due to the presence of cold, low-scattering and high-Q shield crust.
Parvez, Imtiyaz A.; Gusev, Alexander A.; Panza, Giuliano F.; Petukhin, Anatoly G.
Study of seismic response at Stations 6 and 7, El Centro Strong Motion Array, Imperial Valley, California
NASA Astrophysics Data System (ADS)
The process of assembling the shear-strength profiles is described. The profiles were derived from available data based on cone penetration and laboratory tests. A parametric study was conducted in which a number of earthquake motions as well as the strength profiles and their variations were considered as input to nonlinear seismic response computations.
Chen, A. T.
Rupture history of the 2009 L'Aquila (Italy) earthquake from non-linear joint inversion of strong motion and GPS data
We image the rupture history of the 2009 L'Aquila (central Italy) earthquake using a nonlinear joint inversion of strong motion and GPS data. This earthquake ruptured a normal fault striking along the Apennines axis and dipping to the SW. The inferred slip distribution is heterogeneous and characterized by a small, shallow slip patch located up-dip from the hypocenter (9.5 km
A. Cirella; A. Piatanesi; M. Cocco; E. Tinti; L. Scognamiglio; A. Michelini; A. Lomax; E. Boschi
Rupture process of the 2005 West Off Fukuoka Prefecture earthquake obtained from strong motion data of K-NET and KiK-net
We have investigated the rupture process of the 2005 West Off Fukuoka Prefecture earthquake by the multi-time- window linear waveform inversion method using the strong ground motion data recorded at 11 K-NET and KiK-net stations. From the waveforms of the P-wave portion, it is indicated that the energy release in the first few seconds was markedly lower than the subsequent
Haruko Sekiguchi; Shin Aoi; Ryou Honda; Nobuyuki Morikawa; Takashi Kunugi; Hiroyuki Fujiwara
Application of Earthquake Early Warning System and Real-time Strong-motion Monitoring System to Earthquake Disaster Mitigation of a High-Rise Building in Tokyo, Japan
We apply Earthquake Early Warning System (EEWS) and Real-time Strong-motion Monitoring System (RSMS) to reduce earthquake-related damage of the 29-story building of Kogakuin University in the downtown Tokyo, Shinjuku, Japan. EEWS, which is operated by National Research Institute for Earth Science and Disaster Prevention, is the system to provide earthquake information, such as the location and magnitude of an earthquake,
Tomohiro Kubo; Yoshiaki Hisada; Shigeki Horiuchi; Shunroku Yamamoto
Comparing Action Gestures and Classifier Verbs of Motion: Evidence from Australian Sign Language, Taiwan Sign Language, and Nonsigners' Gestures without Speech
ERIC Educational Resources Information Center
Recent research into signed languages indicates that signs may share some properties with gesture, especially in the use of space in classifier constructions. A prediction of this proposal is that there will be similarities in the representation of motion events by sign-naive gesturers and by native signers of unrelated signed languages. This�
Schembri, Adam; Jones, Caroline; Burnham, Denis
Basement Imaging Using Sp Converted Phases in Chia-Nan, Taiwan
NASA Astrophysics Data System (ADS)
The Chia-Nan Plain is a long and narrow alluvial plain, located in the west of Central Mountain Range and the east of Taiwan Strait. We used accelerograms recorded from 1992 to 2010 March by the Taiwan Strong Motion Instrumentation Program (TSMIP) stations to study the thickness variations of the Quaternary alluviums beneath the Chia-Nan Plain, the biggest alluvial plain in Taiwan, by examining a Sp converted phase. The thicknesses are estimated by the travel-time difference of S and Sp waves. This technique of using P-S converted phases had a quite success in the previous study of Lan-Yang Plain. By the high seismic activity and dense of TSMIP stations in this study area, we used this technique to depict the variations of Quaternary sediments thicknesses in Chia-Nan Plain. In general, the thicknesses become thicker toward west. Finally, this approach helps us to discuss the shape of Peikang Basement High in the north of Chia-Nan Plain, which plays an important role in the tectonic changing of Taiwan western foothills.
Wei, J.; Wu, Y.; Chuang, M.; Chang, C.
Field survey around strong motion stations and its implications on the seismic intensity in the Lushan earthquake on April 20, 2013
NASA Astrophysics Data System (ADS)
The M s7.0 Lushan earthquake on April 20, 2013 is another destructive event in China since the M s8.0 Wenchuan earthquake in 2008 and M s7.1 Yushu earthquake in 2010. A large number of strong motion recordings were accumulated by the National Strong Motion Observation Network System of China. The maximum peak ground acceleration (PGA) at Station 51BXD in Baoxing Country is recorded as -1,005.3 cm/s2, which is even larger than the maximum one in the Wenchuan earthquake. A field survey around three typical strong motion stations confirms that the earthquake damage is consistent with the issued map of macroseismic intensity. For the oscillation period 0.3-1.0 s which is the common natural period range of the Chinese civil building, a comparison shows that the observed response spectrums are considerably smaller than the designed values in the Chinese code and this could be one of the reasons that the macroseismic intensity is lower than what we expected despite the high amplitude of PGAs. The Housner spectral intensities from 16 stations are also basically correlated with their macroseismic intensities, and the empirical distribution of spectral intensities from Lushan and Wenchuan Earthquakes under the Chinese scale is almost identical with those under the European scale.
Ren, Yefei; Ji, Kun; Wen, Ruizhi; Huang, Xutao
Earthquake Monitoring and Early Warning Systems in Taiwan (Invited)
The Taiwan region is characterized by a high shortening rate and a strong seismic activity. The Central Weather Bureau (CWB) is responsible for the earthquake monitoring in Taiwan. The CWB seismic network consists of 71 real-time short-period seismic stations in Taiwan region for routinely earthquake monitoring and has recorded about 18,000 events each year in a roughly 400 km x
Y. Wu
Integration of the Shallow Subsurface-Structure Model for Strong Ground Motion Prediction in the Tokyo Metropolitan Area
SUMMARY: A shallow subsurface-structure model improves the accuracy and applicable frequency-range of broadband ground-motion prediction. We have integrated a 3D velocity model of the shallow subsurface structure beneath the Tokyo metropolitan area by compiling about 78,500 borehole data. The model provides the depth of Vs = 500 m\\/s which is compatible with the upper surface of the Shimosa layer, and
Hiroe MIYAKE; Kazuki KOKETSU; Takashi FURUMURA; Yoshiaki INAGAKI; Tetsu MASUDA; Saburoh MIDORIKAWA
Distributed system for strong motion data retrieval and archiving : metadata, databases and data exchange within the NA5 framework
NASA Astrophysics Data System (ADS)
The goal of the NERIES NA5 activity (http://www.neries-eu.org, Improving Accelerometric Data Access) is the development of common access to equally formatted event based accelerometric data and to the corresponding sheet of strong motion parameters. The core of the NA5 is made of 5 European institutes and the final protocol should permit other European institutes to integrate the NA5 portal. More precisely, the aim of the NA5 distributed data system is (1) to make available the data in a in specific format for the engineering community (i.e., ASCII) and in standard format for the seismological community (i.e. full SEED, SAC) and (2) to retrieve data at an unique portal on seismological and - accelerometric criteria, using relations between seismic sources and recordings and using specific parameters for the engineering community, i.e. site conditions and parameter thresholds (e.g., PGA, Ia, Duration, Sa(T), Sv(T)�). Parametric data as well as the procedures to compute them have been defined, implemented and make avalaible for all the NA5 partners. The final product will be a system based on a distributed '3 tiers' architecture, the three main nodes of which are : (1) the primary data servers of NA5 data providers, who make available waveforms (in ascii format) and the associated parameters and events-records tables, via ftp or http protocols (2) the NA5 portal, which supports metadata databases (events and stations metadata) and the associated user interfaces and webservices (3) the NA5 dataserver, the main function of which is the evaluation of the end-users requests, involving data retrieval, data conversion (sac, ascii and miniseed) and metadata formatting (sac, ascii and seed headers). Both NA5 portal and NA5 dataserver are presently under development, the former at EMSC, the latter at LGIT. Our presentation will point out the main features and resources of the NA5 dataserver : - a database of the instrument response files for the accelerometric channels (coefficient, poles and zeros) called PZ database has been set up, as well as some database maintenance tools. The PZ database is hierarchically structured into three directories : sensor, ana_filter and digitizer. - user requests are materialized by a specific xml structure generated at the portal and pushed to the dataserver via QWID/EIDS (Earthquake Information Distribution System). A NA5 xml request contains all the information (metadata) needed for its evaluation : requested data files matching the user search criteria are described by their URL, their network, site of installation and acquisition channel, the events and hypocentral informations they are linked to, as well as values of the parametric data. - the NA5 server notifies a xml parser, which checks and compiles the structure and store the information into an internal permanent relational metadata database. This database and the PZ directory are linked together by the way of a dedicated table, which contains directories and files names. Thus, the NA5 dataserver database will progressively be filled up by values carried on by NA5 requests. - once a request has been loaded into the database, the NA5 archiver process will then fork into four different sub-processes, each of them calling the internal database to get value(s) for its parameters : (a) get the ascii native waveforms files by downloading their URL if needed, i-e if the data are not already stored in the local cache, convert them into sac binary and miniseed (if needed, ie if miniseed files have not already been generated for this native waveforms files). (b) build the linked seed dataless, if the PZ files for these channels are available. (c) build the headers files (such headers will contain some more specific information about event, site condition and soil classification, max accelaration, aso. ) (d) pack the parametric data before archiving and compressing the result. The archiver process will end by filling up and re-writing the xml request file with updated information (archive URL for download, waveforms found and packed, size, etc.),
Pequegnat, C.; Gueguen, P.; Jacquot, R.
Strong motion simulation by the composite source modeling: A case study of 1679 M8.0 Sanhe-Pinggu earthquake
NASA Astrophysics Data System (ADS)
In this study, a composite source model has been used to calculate the realistic strong ground motions in Beijing area, caused by 1679 M S8.0 earthquake in Sanhe-Pinggu. The results could provide us the useful physical parameters for the future seismic hazard analysis in this area. Considering the regional geological/geophysical background, we simulated the scenario earthquake with an associated ground motions in the area ranging from 39.3�N to 41.1�N in latitude and from 115.35�E to 117.55�E in longitude. Some of the key factors which could influence the characteristics of strong ground motion have been discussed, and the resultant peak ground acceleration (PGA) distribution and the peak ground velocity (PGV) distribution around Beijing area also have been made as well. A comparison of the simulated result with the results derived from the attenuation relation has been made, and a sufficient discussion about the advantages and disadvantages of composite source model also has been given in this study. The numerical results, such as the PGA, PGV, peak ground displacement (PGD), and the three-component time-histories developed for Beijing area, have a potential application in earthquake engineering field and building code design, especially for the evaluation of critical constructions, government decision making and the seismic hazard assessment by financial/insurance companies.
Liu, Bo-Yan; Shi, Bao-Ping; Zhang, Jian
English speakers attend more strongly than Spanish speakers to manner of motion when classifying novel objects and events.
Three experiments provide evidence that the conceptualization of moving objects and events is influenced by one's native language, consistent with linguistic relativity theory. Monolingual English speakers and bilingual Spanish/English speakers tested in an English-speaking context performed better than monolingual Spanish speakers and bilingual Spanish/English speakers tested in a Spanish-speaking context at sorting novel, animated objects and events into categories on the basis of manner of motion, an attribute that is prominently marked in English but not in Spanish. In contrast, English and Spanish speakers performed similarly at classifying on the basis of path, an attribute that is prominently marked in both languages. Similar results were obtained regardless of whether categories were labeled by novel words or numbered, suggesting that an English-speaking tendency to focus on manner of motion is a general phenomenon and not limited to word learning. Effects of age of acquisition of English were also observed on the performance of bilinguals, with early bilinguals performing similarly in the 2 language contexts and later bilinguals showing greater contextual variation. PMID:20853990
Kersten, Alan W; Meissner, Christian A; Lechuga, Julia; Schwartz, Bennett L; Albrechtsen, Justin S; Iglesias, Adam
Strong-motion, site-effects and hazard issues in rebuilding Turkey: In light of the 17 August, 1999 earthquake and its aftershocks
The August 17, 1999 Izmit (Turkey) earthquake (Mw=7.4) will be remembered as one of the largest earthquakes of recent times that affected a large urban environment (U.S. Geological Survey, 1999). The shaking that caused the widespread damage and destruction was recorded only by a handful of accelerographs in the earthquake area operated by different networks. The characteristics of these records show that the recorded peak accelerations, even those from near field stations, are smaller than expected. On the other hand, smaller magnitude aftershocks yielded larger peak accelerations. This is attributed to the sparse networks, which possibly missed recording of larger motions during the main shock. As rebuilding of Turkey starts, strong-motion networks that yield essential data must be enlarged. In addition, attention must be paid to new developments elsewhere, such as earthquake zoning maps, earthquake hazard maps, liquefaction potentials and susceptibility. This paper aims to discuss these issues. Copyright??2000 IAHS.
Celebi, M.; Toprak, S.; Holzer, T.
Kinematic Source Rupture Process of the 2008 Iwate-Miyagi Nairiku Earthquake, a MW6.9 thrust earthquake in northeast Japan, using Strong Motion Data
NASA Astrophysics Data System (ADS)
The 2008 Iwate-Miyagi Nairiku earthquake (MJMA7.2) on June 14, 2008, is a thrust type inland crustal earthquake, which occurred in northeastern Honshu, Japan. In order to see strong motion generation process of this event, the source rupture process is estimated by the kinematic waveform inversion using strong motion data. Strong motion data of the K-NET and KiK-net stations and Aratozawa Dam are used. These stations are located 3-94 km from the epicenter. Original acceleration time histories are integrated into velocity and band- pass filtered between 0.05 and 1 Hz. For obtaining the detailed source rupture process, appropriate velocity structure model for Green's functions should be used. We estimated one dimensional velocity structure model for each strong motion station by waveform modeling of aftershock records. The elastic wave velocity, density, and Q-values for four sedimentary layers are assumed following previous studies. The thickness of each sedimentary layer depends on the station, which is estimated to fit the observed aftershock's waveforms by the optimization using the genetic algorithm. A uniform layered structure model is assumed for crust and upper mantle below the seismic bedrock. We succeeded to get a reasonable velocity structure model for each station to give a good fit of the main S-wave part in the observation of aftershocks. The source rupture process of the mainshock is estimated by the linear kinematic waveform inversion using multiple time windows (Hartzell and Heaton, 1983). A fault plane model is assumed following the moment tensor solution by F-net, NIED. The strike and dip angle is 209� and 51�, respectively. The rupture starting point is fixed at the hypocenter located by the JMA. The obtained source model shows a large slip area in the shallow portion of the fault plane approximately 6 km southwest of the hypocenter. The rupture of the asperity finishes within about 9 s. This large slip area corresponds to the area with surface break reported by the field survey group (e.g., AIST/GSJ, 2008), which supports the existence of the large slip close to the ground surface. But, most of surface offset found by the field survey are less than 0.5 m whereas the slip amount of the shallow asperity of the source inversion result is 3-4 m. In north of the hypocenter, the estimated slip amount is small. Slip direction is almost pure dip-slip for the entire fault (Northwest side goes up against southeast side). Total seismic moment is 2.6� 1019 Nm (MW 6.9). Acknowledgments: Strong motion data of K-NET and KiK-net operated by the National Research Institute for Earth Science and Disaster Prevention are used. Strong motion data of Aratozawa Dam obtained by Miyagi prefecture government is also used in the study.
Asano, K.; Iwata, T.
Application of an iterative least-squares waveform inversion of strong-motion and teleseismic records to the 1978 Tabas, Iran, earthquake
An iterative least-squares technique is used to simultaneously invert the strong-motion records and teleseismic P waveforms for the 1978 Tabas, Iran, earthquake to deduce the rupture history. The effects of using different data sets and different parametrizations of the problem (linear versus nonlinear) are considered. A consensus of all the inversion runs indicates a complex, multiple source for the Tabas earthquake, with four main source regions over a fault length of 90 km and an average rupture velocity of 2.5 km/sec. -from Authors
Hartzell, S.; Mendoza, C.
Site correction of stochastic simulation in southwestern Taiwan
NASA Astrophysics Data System (ADS)
Peak ground acceleration (PGA) of a disastrous earthquake, is concerned both in civil engineering and seismology study. Presently, the ground motion prediction equation is widely used for PGA estimation study by engineers. However, the local site effect is another important factor participates in strong motion prediction. For example, in 1985 the Mexico City, 400km far from the epicenter, suffered massive damage due to the seismic wave amplification from the local alluvial layers. (Anderson et al., 1986) In past studies, the use of stochastic method had been done and showed well performance on the simulation of ground-motion at rock site (Beresnev and Atkinson, 1998a ; Roumelioti and Beresnev, 2003). In this study, the site correction was conducted by the empirical transfer function compared with the rock site response from stochastic point-source (Boore, 2005) and finite-fault (Boore, 2009) methods. The error between the simulated and observed Fourier spectrum and PGA are calculated. Further we compared the estimated PGA to the result calculated from ground motion prediction equation. The earthquake data used in this study is recorded by Taiwan Strong Motion Instrumentation Program (TSMIP) from 1991 to 2012; the study area is located at south-western Taiwan. The empirical transfer function was generated by calculating the spectrum ratio between alluvial site and rock site (Borcheret, 1970). Due to the lack of reference rock site station in this area, the rock site ground motion was generated through stochastic point-source model instead. Several target events were then chosen for stochastic point-source simulating to the halfspace. Then, the empirical transfer function for each station was multiplied to the simulated halfspace response. Finally, we focused on two target events: the 1999 Chi-Chi earthquake (Mw=7.6) and the 2010 Jiashian earthquake (Mw=6.4). Considering the large event may contain with complex rupture mechanism, the asperity and delay time for each sub-fault is to be concerned. Both the stochastic point-source and the finite-fault model were used to check the result of our correction.
Lun Huang, Cong; Wen, Kuo Liang; Huang, Jyun Yan
Single-Path Sigma from a Huge Dataset in Taiwan
NASA Astrophysics Data System (ADS)
Ground-motion variability, which was used in the probabilistic seismic hazard analysis (PSHA) in computing annual exceedence probability, is composed of random variability (aleatory uncertainty) and model uncertainty (epistemic uncertainty). Finding random variability of ground motions has become an important issue in PSHA, and only the random variability can be used in deriving the annual exceedence probability of ground-motion. Epistemic uncertainty will be put in the logic tree to estimate the total uncertainty of ground-motion. In the present study, we used about 18,859 records from 158 shallow earthquakes (Mw > 3.0, focal depth ? 35 km, each station has at least 20 records) form the Taiwan Strong-Motion Instrumentation Program (TSMIP) network to analyse the random variability of ground-motion. First, a new ground-motion attenuation model was established by using this huge data set. Second, the residuals from the median attenuation were analysed by direct observation on inter-event variability and site-specific variability. Finally, the single-path variability was found by a moving-window method on either single-earthquake residuals or single-station residuals. A variogram method was also used to find minimum variability for intra-event residuals and inter-event residuals, respectively. Results reveal that 90% of the single-path sigma ?SP are ranging from 0.219 to 0.254 (ln unit) and are 58% to 64% smaller than the total sigma (?T =0.601). The single-site sigma (?SS) are also 39%-43% smaller. If we use only random variability (single-path sigma) in PSHA, then the resultant hazard level would be 28% and 25% lower than the traditional one (using total sigma) in 475-year and in 2475-year return period, respectively, in Taipei.
Sung, Chih-Hsuan; Lee, Chyi-Tyi
Estimation of Strong Ground Motion from a Great Earthquake Mw 8.5 in Central Seismic Gap Region, Himalaya (India) Using Empirical Green's Function Technique
NASA Astrophysics Data System (ADS)
In the present study ground motions for a Mw 8.5 scenario earthquake are estimated at 13 sites in Kumaun-Garhwal region using the empirical Green's function technique. The recordings of 1991 Uttarkashi earthquake of Mw 6.8 at these sites are used as an element earthquake. A heterogeneous source model consisting of two asperities is considered for simulating the ground motions. The entire central seismic gap (CSG) can expect acceleration in excess of 100 cm/s2 with NW portion in excess of 400 cm/s2 and SE between 100 and 200 cm/s2. The central portion can expect peak ground acceleration (PGA) between 200 and 400 cm/s2. It has been observed from simulation of strong ground motion that sites located near the rupture initiation point can expect accelerations in excess of 1 g. In the present analysis, Bhatwari and Uttarkashi can expect ground accelerations in excess of 1 g. The estimates of the PGA are compared with earlier studies in the same region using different methodologies and it was found that the results are comparable. This has put constrains on the expected PGAs in this region. The obtained PGA values can be used in identifying the vulnerable areas in the central Himalaya, thereby facilitating the planning, design and construction of new structures and strengthening of the existing structures in the region.
Sharma, Babita; Chopra, Sumer; Sutar, Anup Kumar; Bansal, B. K.
Site amplification and strong ground motion of the 2007 Noto Hanto, Japan, earthquake estimated from aftershock observation
NASA Astrophysics Data System (ADS)
Site amplifications in the lowlands most affected by the 2007 Noto Hanto earthquake, Monzen, Anamizu, and Wajima, are examined using aftershock records observed at eight temporary seismic stations installed just after the mainshock and at two K-NET stations. The predominant frequencies of spectral ratios at alluvium sites in Anamizu and Wajima are approximately 1 Hz. Site amplifications at the alluvium sites are successfully reproduced from 1-D response analysis, except for that at ISK005 where 2-D or higher amplification effects are inferred to play a significant role. A source model composed of two asperities reproduces the ground motions of the mainshock using the empirical Green's function method. The seismic moments of the asperities are 3.76�1018 N m and 2.21�1018 N m, respectively. Peak ground velocity (PGV) at alluvium sites during the mainshock are estimated to be 70-110 cm/s for Monzen, 50-110 cm/s for Anamizu, and 60-70 cm/s for Wajima.
Yoshimi, M.; Yoshida, K.
The ground motion simulation of the blind fault event, and the case study of two different focal mechanisms during the 1999 Chiayi, Taiwan, earthquake sequence
NASA Astrophysics Data System (ADS)
The 1999 Chiayi earthquake (M 6.4; 1999/10/22) sequence occurred on a blind fault under a depth of 10 km in the Chiayi-Tainan area. This earthquake sequence occurred only one month after the 1999 Chi-Chi earthquake and caused some injuries and damage. Although the thrust motion of main shock of Chiayi earthquake sequence was consistent with the regional tectonics, its M6.0 aftershock occurred almost at the same location one hour later with a strike-slip focal mechanism. The Chiayi-Tainan area has been suggested as the region with high probability to generate large earthquake due to the rapid convergence plate strain rate, the indistinct location and mechanism of blind fault could cause a more serious disaster. In order to understand the dynamic rupture behavior and the potential hazard of this blind fault, we performed dynamic simulations of blind fault with various fault geometries, focal mechanisms and velocity structures. In addition, with the advantage of dense distribution of seismic stations in the Chiayi-Tainan area, we would investigate the rupture properties of the 1999 Chaiyi earthquake and its M6.0 strike-slip aftershock for the further discussion.
Wen, Y.
An initial model of seismic microzonation of Sikkim Himalaya through thematic mapping and GIS integration of geological and strong motion features^*
NASA Astrophysics Data System (ADS)
Seismic microzonation and hazard mapping was undertaken in the Sikkim Himalaya with local site conditions and strong ground motion attributes incorporated into a geographic information system. A strong motion network in Sikkim consisting of 9 digital accelerographs recorded more than 100 events during 1998-2002, of which 72 events are selected with signal-to-noise ratios ?3 for the estimation of site response (SR), peak ground acceleration (PGA) and resonance frequency (RF) at all stations. With these data and inputs from IRS-1C LISS III digital data, topo-sheets, geographical boundary of the State of Sikkim, surface geological maps, soil taxonomy map at 1:50,000 scale and seismic refraction profiles, the seismological and geological thematic maps, namely, SR, PGA, RF, lithology, soil class, slope, drainage, and landslide layers were generated. The geological and seismological layers are assigned normalized weights and feature ranks following a pair-wise comparison hierarchical approach and later integrated through GIS to create the microzonation map of the region. The overall SR, PGA and resonance frequency show an increasing trend in a NW-SE direction, peaking at Singtam in the lesser Himalaya. Six major hazard zones are demarcated with different percentages of probability index values in the geological, seismological hazard and microzonation maps. The maximum risk is attached to a probability greater than 78% in the Singtam and adjoining area. These maps offer generally better spatial representation of seismic hazards including site-specific analysis as a first level microzonation attempt.
Nath, Sankar Kumar
The 1999 Izmit, Turkey, earthquake: Non-planar fault structure, dynamic rupture process and strong ground motion
NASA Astrophysics Data System (ADS)
The fault trace of the 1999 Izmit, Turkey, earthquake is incomplete, because it is buried or covered by a lake and a gulf. We modeled dynamic rupture propagation along various non-planar fault models, which are inferred by geological observation and geodesic analyses, using 3D-BIEM (boundary integral equation method). Geological observation of surface fault traces implies complex non-planar fault structures, while InSAR and SPOT images give a smoother fault structure consisting of a few segments. We study three points which may show geological irregularities; 1) 25 km east of the hypocenter under Sapanca lake, between the Izmit-Sapanca lake (IS) and the Sapanca-Akyazl (SA) segments, 2) 60 km east at the Akyazl basin, between the SA and the Karadere (K) segments, and 3) 10 km west under the sea between the Karamursel-Golcuk (KG) and IS segments. In numerical simulation, we focus on rupture directivity, slip distribution and rupture velocity. As a preliminary situation, we assume a uniform regional stress favorable on the primary segment (IS) and a simple depth-dependent slip-weakening law. We discuss the relation between the irregularity of fault orientation and rupture process. From numerical simulations, each fault discontinuity is treated as 1) a small bend of a few degrees, 2) a bend of about 25o which causes differences in initial stress field along the SA and K segments enough for rupture to stop, and 3) a jog which may disturb westbound rupture propagation. We conclude that fault geometry and orientation constrain the rupture process in the 1999 Izmit earthquake, and that they may cause difference in ground motion eastward and westward of the hypocenter.
Aochi, H.; Madariaga, R.
A Study of the Influence of Organizational Knowledge Ability and Knowledge Absorptive Capacity on Organization Performance in Taiwan`s Hi-Tech Enterprises
NASA Astrophysics Data System (ADS)
In recent years, business operation tends to be internationalized and the production cost increases day by day, the technology promotion of Taiwan`s hi-tech enterprises met its bottleneck; lots of industries have introduced Knowledge Management (KM) and emphasized the knowledge absorptive capacity of the employees to promote the organizational business performance under this competition environment. This research studied the influence of organizational knowledge ability and knowledge absorptive capacity on organization performance in Taiwan`s hi-tech enterprises. The research found that: the industry with strong organizational knowledge ability has positive influence on organization performance; the industry with strong organizational knowledge ability has positive influence on knowledge absorptive capacity and the industry with strong knowledge absorptive capacity has positive influence on organization performance. Therefore, the organizational knowledge ability and knowledge absorption capacity of Taiwan`s high-tech enterprises have positive influence on the promotion of their organization performance.
Chen, Ching-Piao; Liu, Pang-Lo; Tsai, Chih-Hung
Source Process of the 2011 Great Tohoku earthquake Inferred from Waveform Inversion with Long-Period Strong-Motion Records and its Validation by Tsunami Simulation
NASA Astrophysics Data System (ADS)
We have investigated the rupture process of the 2011 off the Pacific coast of Tohoku earthquake by the multi-time-window linear waveform inversion method using the long-period strong-ground motion data. From the record section of the long-period motion of the 3 phases, it is indicated that the rupture process mainly consists of the 3 stages. We assumed a single planar fault model of 468 km long in strike and 228 km wide in dip. We used the strong-motion data obtained from 37 stations of F-net and KiK-net (NIED), and 1 station of Hokkaido University for the inversion. The seismic moment of this earthquake was estimated to be 4.3e22 Nm (Mw 9.0). The inverted slip distribution shows a large asperity with a maximum slip of about 47 m which is located on the shallower part of the fault plane (Fig. 1A). The rupture process is divided into three stages: first stage with moderate slip; second stage with large and long-duration slip in the shallow part of the fault; and third stage with relatively small and short-duration slip in the southern part of the fault. The feature of the ground motion suggested from the record section is well represented by the peak moment rate distributions (Fig. 1B), rather than the slip distributions. Rupture velocity is around 3.4 km/s in the first and third stages, while rupture progression suspended for a while before the rupture of the asperity. We validated this model with tsunami simulation using fully nonlinear Bousinessq type model of tsunami-wave propagation. We compared the tsunami simulation result with observation data and with results of simulation using other source models. Simulation results fit observed tsunami waves in the off-shore area, and inundation heights on the coast of Sendai and Fukushima. On the Sanriku coast simulated amplitudes are smaller than observed ones. Possible reason of the underestimated simulated amplitudes is a small resolution of used bathymetry data for this area.
Yoshida, K.; Petukhin, A.; Miyakoshi, K.; Irikura, K.
Since 1993, the government of Taiwan has allocated approximately $60 million to help the pharmaceutical industry in the area of biotechnology and pharmaceutical science research and development. The government has chosen to promote drug research and development as part of a national policy to target the pharmaceutical manufacturing industry as one of Taiwan's strategic industries. To cope with this development,
K. C. Chen
Rupture process and wave radiation characteristics of the 2011 Tohoku-Oki mega-thrust earthquake examined using the strong-motion data
NASA Astrophysics Data System (ADS)
The 2011 Tohoku-Oki earthquake is the first M9 earthquake that has been recorded by the dense strong-motion networks in the near-fault region. The strong-motion waveforms obtained by the two nation-wide networks, K-NET and KiK-net operated by the National Research Institute for Earth Science and Disaster Prevention (Aoi et al., 2011, Kunugi et al., 2011, this meeting), can provide the detailed information about the source of the mega-thrust earthquake. As a first step to elucidating the generation mechanism of this devastating earthquake that caused the severe ground shaking and catastrophic tsunami, we derive the rupture process using the relatively low-frequency (0.01-0.125 Hz) strong-motion data. We performed the multi-time-window linear waveform inversion analysis. The derived slip model has one prominent large slip area extending from the area around the hypocenter to the shallow part of the fault plane along the trench axis. This shallow large slip area is located far off southern Iwate, Miyagi, and northern Fukushima prefectures, where the tsunami damage was huge. The rupture of this area started 60 s after the initial break with a long duration of 40 s. This rupture event radiated the seismic waves rich in very low-frequency content. The deep portion of the fault between the hypocenter and the coast of Miyagi prefecture experienced the two down-dip rupture events in 20-50 s and 60-100 s, which largely contributed to the waveform synthesis at the stations to the west of the central part of the fault plane although the slip there is relatively small compared to the shallow slip area along the trench axis. Particularly, the second rupture event makes a significant contribution to the phase with largest amplitude. The shallow large slip also contributes to this largest amplitude phase. The former and latter make contribution in relatively high and low frequency ranges, respectively. Rupture after 100 s propagated in the southern part of the fault and generated the distinct phase observed in the southern stations. We also examine the frequency dependency of the wave radiation process considering the features of the observed acceleration waveforms.
Suzuki, W.; Aoi, S.; Sekiguchi, H.; Kunugi, T.
Rupture-process images deduced from array back-projection analysis using data of a dense strong ground-motion seismograph network
NASA Astrophysics Data System (ADS)
An M6.5 earthquake occurred beneath Suruga Bay on 11 August 2009. Japanese seismic intensity scale 6- was recorded near the source region. The earthquake on 11 August occurred in the Philippine Sea plate which subducts beneath the Tokai region on the Suruga Trough and the mechanism was estimated as a thrust-type with strike-slip components. The rupture area is within the expected source region of the so-called M8 Tokai earthquake. Although strong ground motions were observed widely around the source area, it is difficult to recover the rupture process by the waveform inversions in detail, because magnitude of the earthquake is not so large and the dominant frequency is outside of suitable range for the waveform inversions. In this study, we estimated the rupture process by performing an array back-projection analysis (e.g., Honda and Aoi, 2009). A strong ground motion seismograph network has been deployed in Hakone caldera about 40 km to the northeast from the source region. The seismograph network was regarded as a dense array. Hereafter, we call the array as HK-net. Resolution of the analysis is affected by the array size. Seismographs of HK-net are distributed extensively in Hakone caldera whose diameter is about 10 km and the site separations in HK-net are less than 1 km. We expected that this array configuration is appropriate for the analysis using the waveforms whose frequency range is higher than 1 Hz. The waveforms are band-pass filtered in the frequency range of 0.5-5Hz and integrated into velocity. We adopted the hypocenter determined by NIED (138.502, 34.805, 21.6km) and took the nodal plane dipping south-eastward as the fault plane on which the hypocenter was located, although aftershocks were also seen to have been distributed on another plane dipping northeastward. Two peaks appeared in strong ground motion records observed in HK-net and this means there are two sources (asperities) on the fault. In order to determine the sources of the pulses, semblance-enhanced waveform stacking was performed. By projecting the power of the stacked waveforms on to the fault plane, two asperities that generated significant pulses were successfully imaged at the hypocenter and the northwestern edge of the fault, respectively. The rupture seems to have started at the hypocenter and propagated unilaterally toward the northwestern edge of the fault. These results agree with the fact that two pulses were observed only at the eastern side of the source region but not observed at the western side, which is reasonable if the directivity effect is taken into account.
Honda, R.; Yukutake, Y.; Tanada, T.; Yoshida, A.
NSDL National Science Digital Library
Developed and maintained by Y.C. Chi, this site hosts a large collection of full text documents relating to Taiwan's international relations, history, and legal status. These include treaties dating from 1662 to 1978, documents from World War II, Joint Communiques with Japan and the US, Taiwan-related US legislative activity, and UN documents, among others. The site also features two essays by the site author: an executive summary of international agreements affecting Taiwan's status and a discussion on sovereignty. A number of short pieces on non-legal considerations about the status of Taiwan are planned for the near future. While scholars and others involved on either side of the debate on Taiwan's status may not agree with the site author's views, the original full text documents speak for themselves.
Chi, Y. C.
Free flux flow resistivity in a strongly overdoped high-Tc cuprate: The purely viscous motion of the vortices in a semiclassical d-wave superconductor
NASA Astrophysics Data System (ADS)
We report the free flux flow (FFF) resistivity associated with a purely viscous motion of the vortices in a moderately clean d-wave superconductor Bi:2201 in the strongly overdoped regime (Tc=16 K) for a wide range of the magnetic field in the vortex state. The FFF resistivity is obtained by measuring the microwave surface impedance at different microwave frequencies. It is found that the FFF resistivity is remarkably different from that of conventional s-wave superconductors. At low fields (H<0.2Hc2) the FFF resistivity increases linearly with H with a coefficient which is far larger than that found in conventional s-wave superconductors. At higher fields, the FFF resistivity increases in proportion to (H) up to Hc2. Based on these results, the energy dissipation mechanism associated with the viscous vortex motion in ``semiclassical'' d-wave superconductors with gap nodes is discussed. Two possible scenarios are put forth for these field dependences: the enhancement of the quasiparticle relaxation rate and the reduction of the number of the quasiparticles participating the energy dissipation in d-wave vortex state.
Matsuda, Y.; Shibata, A.; Izawa, K.; Ikuta, H.; Hasegawa, M.; Kato, Y.
Finite-difference Simulation of Strong Motion From a Sub-oceanic Earthquake: Modeling Effects of Land and Ocean-bottom Topographies
NASA Astrophysics Data System (ADS)
For accurate simulation of strong ground motion from a sub-oceanic earthquake, the topographies of land and sea floor should be included as well as sea water layer in the computation. In the finite-difference method (FDM), which has been widely used for seismic modeling, approaches to model land topography (free-surface boundary) and schemes for ocean-bottom topography (liquid-solid boundary) have been independently presented and described. For the staggered-grid FDM, Ohminato and Chouet (1997, BSSA) proposed a simple and stable technique implementing free-surface topography. On the other hand a similar stable technique but for liquid-solid boundary topography was described by Okamoto and Takenaka (2005, Zisin). Recently we have proposed a unified algorithm of both techniques using a material-cell based averaging for the staggered-grid FDM to compute seismic wave propagation in models with both land and ocean-bottom topographies (Takenaka et al., 2009, 9th SEGJ Int. Symp.). In this study we apply the algorithm to simulation of a real sub-oceanic earthquake: the 2009 Suruga Bay, Japan, earthquake (Mw6.3), which is an intraslab earthquake occurring at 5:07 a.m. on August 11, 2009 (JST; JST=UT+9h) at the eastern tip of the Supposed Tokai earthquake source area (the largest seismic intensity observed 6-, JMA). We here call our FDM scheme HOT-FDM, which can model 3D Heterogeneity, Oceanic layer and Topography of the target structure as well as its anelastic attenuation property (Qp, Qs). Through the realistic simulations of the 2009 Suruga Bay earthquake we particularly demonstrate the effects of land and ocean-bottom topographies on strong ground motion from a sub-oceanic earthquake.
Nakamura, T.; Takenaka, H.; Okamoto, T.; Kaneda, Y.
Taper Angle Evolution in Taiwan Accretionary Wedge
NASA Astrophysics Data System (ADS)
Liwen Chena,b, Wu-Cheng Chia, Char-Shine Liuc aInstitute of Earth Sciences, Academia Sinica, Taipei, Taiwan bInstitute of Geosciences, National Taiwan University, Taipei, Taiwan cInstitute of Oceanography, National Taiwan University, Taipei, Taiwan The critical taper model, originally developed using onland Taiwan as an example, is governed by force balance of a horizontal compressional wedge. This model has been successfully applied to many mountainous regions around the world. Among them, Taiwan is located in an oblique collision between the Luzon Arc and the Chinese Passive margin. Previous critical taper angle studies of Taiwan are mainly focusing on utilizing land data. In this study we want to extend these studies to offshore region from the subduction zone to collision zone. Here we study the varying taper angles of the double-vergent wedge derived from 1,000 km of reflection seismic profiles in both the pro-wedge and retro-wedge locations. These profiles were collected in the last two decades. For the retro-wedge, the topography slope angle changes from 2 to 8.8 degrees; some of the steep slope suggests that some part of the retrowedge is currently in a super-critical angle state. Such dramatic changes in taper angle probably strongly affect regional sedimentary processes, including slumping, in addition to structural deformation. These complex processes might even help develop a m�lange or re-open a closed basin. We are currently working on studying the taper angle evolution of the pro-wedge from subduction to arc-continent collision zone in the offshore region. Though further works are needed, our preliminary results show that the evolution of wedge angles and the geometry of the wedge are closely linked and inseparable. The structures of the subducting plate might have strong influence on the deformation style of the over-riding plate. It would be interesting to combine the angle variation with the structure interpretation of the accretionary wedge, both in the pro- and retro-wedge regions. And the results might help us to better understand the evolution of Taiwan Accretionary Prism.
Chen, L.; Chi, W.; Liu, C.
Site Amplification Characteristics and Their Relationship with Averaged S-wave Velocities Derived From K-NET and KiK-Net Strong Motion Records in Japan
NASA Astrophysics Data System (ADS)
To predict strong ground motions for future scenario earthquake in a broad-band frequency, we need to characterize both source spectra and site amplification. For high frequency we can use statistical method based on the observed records and the summation technique. Thanks to the advent of the K-Net and KiK-net (by NIED) in Japan, we have now plenty of weak motion data, enough to construct statistical Green_fs functions. In order to represent long- and intermediate period nature of the strong ground motion in the near field region, we want to use theoretical technique such as three-dimensional finite difference method. Any theoretical methods need S-wave velocity structures that should reproduce the observed site amplification quantitatively. In this study we perform first the analysis to separate the so-called source spectra, attenuation coefficient, and the site amplification factors from about 15,000 K-NET, KiK-Net, and JMA records observed at 1,700 stations in Japan. The separation method is the well-established one of Andrews (1980) and the resultant source spectra are modeled as omega-square spectra. As a reference site we use one rock station of KiK-Net in Yamaguchi Prefecture, from which we remove amplification of shallow surface deposits. Once we obtain site amplification factors, we try to reproduce them by using one-dimensional S-wave velocity structures below each site of K-NET and KiK-Net (in total, 1,300). We use Genetic Algorithm to invert the S-wave structures with fixed S-wave velocities in the shallow part. We succeed to reproduce site amplification factors at about one thirds of the sites very well. The majority of not-so-good sites need modification of S-wave velocities in the shallow part based on logging data. We also perform the same kind of separation analysis for PGA, PGV, and JMA Seismic Intensity. We found that PGA site factors correlate best with 5.0 Hz spectral amplification and PGV 2.5 Hz spectral amplification. We also found that the best correlation of site factors can be obtained with the average S wave velocity only for top 5 m for PGA and 10 m to 20 m for PGV. Since we have a space for better representation of velocity structures, the results reported here are not conclusive. Once we get better S-wave velocity structures at as many sites as possible, we expect to extrapolate them and construct an initial model of the three-dimensional basin structure of the whole Japanese islands.
Kawase, H.; Matsuo, H.
S-wave velocity structures of sediments estimated from array microtremor records and site responses in the near-fault region of the 1999 Chi-Chi, Taiwan earthquake
The 1999 Chi-Chi, Taiwan earthquake, MW = 7.6, caused severe damage in the near-fault region of the earthquake. In order to evaluate site effects in the near-field strong motions we estimate S-wave velocity structures of sediments at four sites using array records of microtremors. We also recalculated S-wave velocity structures at other four sites previously reported. To show the validity
Satoh Toshimi; Hiroshi Kawase; Tomotaka Iwata; Sadanori Higashi; Sato Toshiaki; Huey-Chu Huang
Educational Technology in Taiwan.
ERIC Educational Resources Information Center
Examines educational technology applications in Taiwan. Highlights include historical background; learning technology integration; computer availability; teacher training; student and teacher attitudes; computer-mediated communication and collaboration; curriculum planning; distance education; and an educational technology model that includes�
Tu, Chih-Hsiung; Twu, Hui-Ling
National Technical Information Service (NTIS)
This general guide highlights some of the areas that investors should be aware of when doing business in Taiwan, although professional advice may be required in specific circumstances. Below are a few competitive advantages for investors conducting their ...
Characteristics of the High-Frequency Energy Release of the M9.0 Tohoku-Oki Earthquake Determined from Strong-Motion Recordings
NASA Astrophysics Data System (ADS)
The spatial distribution, timing, and stress drop of the high-frequency (0.2-20 Hz) energy release of the Mw9.0 Tohoku-Oki earthquake were determined from strong-motion recordings from KiK-net and K-net. The locations of the initiation points of the three major high-frequency sub-events and the smaller patches of moment release within them were discerned using correlated arrivals on closely-spaced stations. The high-frequency energy release occurred landward of the area near the trench with the highest slip. The first sub-event started southwest of the hypocenter and ruptured to the north, although there may have been a component of southward rupture. The second major sub-event initiated about 50 km north of the starting point of sub-event 1 and ruptured to the south at about 2.2 km/s. This second sub-event occurred after the initiation of long rise time slip near the trench. The third major sub-event was located about 160 km south of the initiation point of sub-event 2. The velocity pulse for the third sub-event was remarkably compact, with a pulse duration of about 2 s on some stations. Smaller sub-events occurred south of sub-event 3. The high-frequency spectral amplitudes ( > 1 Hz) of sub-event 1 at close-in stations are similar to those of the M7.4 aftershock of April 7, although the rise time of slip for the sub-event was much longer than that of the aftershock. Finite-fault stochastic simulations are used to determine the stress drop of the main shock and major aftershocks. The strong-motion records of the Tohoku-Oki main shock have lower spectral amplitudes at 0.2-0.4 Hz than those of the Mw8.1 Tokachi-Oki earthquake at close-in stations, which is likely caused by differences in the distribution of rise time of slip on the rupture surface and the distance to the area of maximum slip.
Frankel, A. D.
High-frequency source radiation during the 2011 Tohoku-Oki earthquake, Japan, inferred from KiK-net strong-motion seismograms
NASA Astrophysics Data System (ADS)
Kumagai, Hiroyuki; Pulido, Nelson; Fukuyama, Eiichi; Aoi, Shin
A seismic hazard scenario in the Sikkim Himalaya from seismotectonics, spectral amplification, source parameterization, and spectral attenuation laws using strong motion seismometry
NASA Astrophysics Data System (ADS)
In this paper, we present a seismic hazard map of the Indian Himalayan State of Sikkim, lying between Nepal and Bhutan Himalaya, in terms of horizontal peak ground accelerations with 10% exceedance probability over the next 50 years. These figures, the first for the region, were calculated through a stepwise process based on (1) an estimation of the maximum credible earthquake (MCE) from the seismicity of the region and Global Seismic Hazard Assessment Program considerations and (2) four seismotectonic parameters abstracted from accelerograms recorded at nine stations of the Sikkim Strong Motion Array, specifically installed for this study. The latter include (1) the frequency-dependent power law for the shear wave quality factor, QS, (2) the site response function at each station using receiver function analysis and generalized inversion, (3) source parameterization of various events recorded by the array and application of the resulting relationships between M0 and MW, and corner frequency, fc and MW to simulate spectral accelerations due to higher-magnitude events corresponding to the estimated MCE, and (4) abstraction of regional as well as site specific local spectral attenuation laws at different geometrically central frequencies in low-, moderate-, and high-frequency bands.
Nath, Sankar Kumar; Vyas, Madhav; Pal, Indrajit; Sengupta, Probal
Rupture process of the 2005 West Off Fukuoka Prefecture earthquake obtained from strong motion data of K-NET and KiK-net
NASA Astrophysics Data System (ADS)
We have investigated the rupture process of the 2005 West Off Fukuoka Prefecture earthquake by the multi-time- window linear waveform inversion method using the strong ground motion data recorded at 11 K-NET and KiK-net stations. From the waveforms of the P-wave portion, it is indicated that the energy release in the first few seconds was markedly lower than the subsequent part, and this causes difficulty in identifying onset of the S-wave. To decide an appropriate time window for the waveform inversion, we estimate the S-wave onset using aftershock records. The inverted slip distribution shows a single asperity of 8 km � 6 km and its center located 8 km to the southeast and 6 km above the hypocenter. The asperity explains most of the large-amplitude signals in the observed waveforms. The turning point from the initial low-energy-release rupture to the main high-energy-release rupture is estimated from the spatial variation of the observed initial rupture phase. It is found 3.3 s after the initiation of the rupture at about 4 km to the southeast of the hypocenter. Stress drop during the initial rupture is estimated to be in the same order of those of moderate size aftershocks, which indicates that the initial rupture is an ordinary dynamic rupture.
Sekiguchi, H.; Aoi, S.; Honda, R.; Morikawa, N.; Kunugi, T.; Fujiwara, H.
Philippine Sea Slab and South-Ryukyu Arc Sliver Accommodation of Arc-Continent Collision East of Taiwan
NASA Astrophysics Data System (ADS)
The southern termination of the Ryukyu arc-trench system underwent a complex polyphased and extremely rapid tectonic evolution during the last 5 to 8 My. At first, the relative motion of the Philippine Sea plate (PSP) has changed about 5 My ago from a northward to a northwestward motion relative to Eurasia. Secondly, the Ryukyu trench has propagated from east to west during the same time period resulting in a tectonic inversion along the former passive margin of the South China Sea into the active margin of the S-Ryukyu trench. Thirdly, the convergence rate along the neo-formed S-Ryukyu trench dramatically increased from 8 to 13 cm/yr since at least 2 My when the Southern Okinawa Trough (SOT) started to rift. At the same time, the oceanic subduction of the South China Sea beneath the northern Manila arc progressively evolved into a continental subduction of the Chinese platform at the origin of the Taiwan orogen. The timing of these various kinematic and tectonic events should have been recorded in the deformed sedimentary basins and fold-and-thrust belts in the region. Unfortunately, a large part is now below the sea-level and no or a few age constraints are available. The recent joint project between Taiwan-USA & France (TAIGER & ACTS) gave us the opportunity to considerably increase the resolution of the seismic imagery around the island and especially in the most highly deformed area east of Taiwan along the S-Ryukyu forearc. We already knew that the seismic activity focussed in this region but we ignored how the converging plates deformed. We can now argue that the PSP strongly deforms in the vicinity of its deep interaction with the root of the Taiwan orogen. The north-dipping PSP slab buckles and tears along two diverging directions with a down-faulted part subducting beneath the SOT.
Lallemand, S.; Theunissen, T.; Font, Y.; Schnurle, P.; Lee, C.; Liu, C.
High-rate GPS seismology for the 2013 ML 6.4 Wanrung, Taiwan earthquake
NASA Astrophysics Data System (ADS)
The 31 October 2013 ML 6.4 Wanrung earthquake was well recorded by twenty-five 1-Hz and sixteen 10-Hz GPS receivers and twenty-five seismometers located within the epicentral distance of about 80 km. Precise Point Positioning kinematic solutions estimated by software VADASE, RTKLIB, and GIPSY are used to obtain the co-seismic deformations and dynamic displacements. We used seismograms recorded by broadband seismometers and strong motion accelerometers to verify the capability of high-rate GPS for the detections of the body waves and surface waves generated by a moderate-size earthquake. Results show that the overall standard deviations of the position time series are ~6 mm and ~20 mm in the horizontal and vertical components, respectively after applying spatial filtering. Largest co-seismic displacement derived from high-rate GPS is nearly twenty centimeter at 5 km northeast of the epicenter. S waves and surface waves are successfully detected by motions of 10-Hz GPS and double-integrated accelerometers within the 15 km epicentral distance. We also found that a group of later phases of ~1-2.5 cm peak-to-peak amplitudes with a frequency range of 0.2-0.5 Hz located within the Longitudinal Valley, a suture zone composed of Holocene thick sediment deposits. The 2013 Wanrung, Taiwan earthquake recorded by the high-rate GPS network in Taiwan demonstrates the feasibility of GPS Seismology for a moderate size earthquake at a local scale.
Hung, Huang-Kai; Rau, Ruey-Juin; Colosimo, Gabriele; Benedetti, Elisa; Branzanti, Mara; Crespi, Mattia; Mazzoni, Augusto
Investigating source directivity for the 2012 Ml5.9 Emilia (Northern Italy) earthquake by jointly using High-rate GPS and Strong motion data
NASA Astrophysics Data System (ADS)
On May, 20th 2012, the Ferrara and Modena provinces (Emilia Romagna, Northern Italy) were struck by a moderate magnitude earthquake (Ml 5.9). The focal mechanism is consistent with a ~E-W-striking thrust fault. The mainshock was recorded by 29 high-rate sampling (1-Hz) continuous GPS (HRGPS) stations belonging to scientific or commercial networks and by 55 strong motion (SM) stations belonging to INGV (Istituto Nazionale di Geofisica e Vulcanologia) and RAN (Rete Accelerometrica Nazionale) networks, respectively. The spatial distribution of both HRGPS and SM stations with respect to the mainshock location allows a satisfactory azimuthal coverage of the area. To investigate directivity effects during the mainshock occurrence, we analyze the spatial variation of the peak ground displacement (PGD) measured either for HRGPS or SM sites, using different methods. For each HRGPS and SM site, we rotated the horizontal time series to the azimuth direction and we estimated the GPS-related and the SM-related peak ground displacement (G-PGD and S-PGD, respectively) retrieved by transverse component. However, in contrast to GPS displacements, the double integration of the SM data can be affected by the presence of drifts and, thus, they have to be corrected by quasi-manual procedures. To more properly compare the G-PGDs to the S-PGDs, we used the response spectrum. A response spectrum is simply the response of a series of oscillators of varying natural frequency, that are forced into motion by the same input. The asymptotic value of the displacement response spectrum is the peak ground displacement. Thus, for each HRGPS and SM site, we computed the value of this asymptotic trend (G-PGDrs and S-PGDrs, respectively). This method allows simple automatic procedures. The consistency of the PGDs derived from HRGPS and SM is also evaluated for sites where the two instruments are collocated. The PGDs obtained by the two different methods and the two different data types suggest a source directivity effect in the SE (~120�-150�N) direction.
Avallone, A.; Herrero, A.; Latorre, D.; Rovelli, A.; D'Anastasio, E.
Neurotrauma research in Taiwan.
Because of the rapid industrial and economic growth, Taiwan and other developing countries have faced an enormous increase in the number of motorcycles, which has subsequently caused a rapid increase of the motorcycle-related traumatic brain injuries (TBI). In order to tackle this serious problem, stepwise approaches for TBI were implemented in Taiwan from 1991 to 2007. Step 1 was to do a nationwide TBI registry in order to identify the risk factors and determinants. We found that the major cause of TBI in Taiwan was motorcycle-related injury, and very few motorcyclists wore a helmet. Step 2 was to launch the implementation of the helmet use law on June 1, 1997. A rapid decline of TBI hospitalizations and deaths was demonstrated soon thereafter. Step 3 was to enroll into international collaborations with the Global Spine and Head Injury Prevention Project (Global SHIP Project) groups for TBI. The comparative results thus obtained could be used to develop prevention strategies for developing countries. Step 4 was to implement clinical researches for TBI, which included a Propofol study, hyperbaric oxygen therapy (HBOT), brain parenchymal oxygen (PbtO2) monitoring, etc. Step 5 was to develop guidelines for the management of severe TBI in Taiwan. Through a 2-year period of review, discussion, and integration, a 9-chapter guideline was published in June 2007. In summary, our experience and process for management of TBI in Taiwan can be used as a reference for other developing countries. PMID:18642644
Lin, J W; Lin, C M; Tsai, J T; Hung, K S; Hung, C C; Chiu, W T
High-frequency source radiation during the 2011 Tohoku-Oki earthquake, Japan, inferred from KiK-net strong-motion seismograms
NASA Astrophysics Data System (ADS)
To investigate source processes of the Tohoku-Oki earthquake, we analyzed high-frequency waveform data from a Japanese nationwide strong-motion network of the KiK-net, which have not been systematically used in previous studies. We applied a source location method using high-frequency (5-10 Hz) seismic amplitudes to KiK-net waveform data in the Tohoku region to estimate the spatio-temporal rupture processes of the earthquake. In our amplitude source location (ASL) method, we assumed far-field isotropic radiation of S waves, and conducted a spatial grid search to find the best fitting source locations along the subducted slab in individual successive time windows starting from the earthquake origin time. The isotropic S-wave radiation assumption may become valid in a high-frequency range because of the path effect caused by the scattering of seismic waves. We performed a series of synthetic tests, which showed that the ASL method has the resolution to estimate source locations on the assumed fault along the plate. However, our tests also indicated that ASL results contain artifacts caused by the limited station coverage and noise effects. Our application of the ASL method to the Tohoku-Oki earthquake resulted in repetitive sources near the trench. However, the estimated source location in the first time window was inconsistent with the hypocenter determined from onset arrival times, and the seismograms reconstructed from source amplitudes at the best fitting source locations in the individual time windows showed discrepancies with the observed seismograms. We therefore concluded that the source locations near the trench may reflect artifacts. We then assumed various source node distributions along the plate, and found that the observed seismograms were most reasonably explained when assuming deep source nodes. This result suggests that the high-frequency seismic waves were radiated at deeper depths during the earthquake, a feature which is consistent with the results previously obtained from teleseismic back-projection and strong-motion source model studies. We identified three high-frequency sub-events, and compared them with the moment-rate function estimated from low-frequency seismograms. Our comparison indicated that no significant moment release occurred during the first high-frequency sub-event and the largest moment-release pulse occurred almost simultaneously with the second high-frequency sub-event. Since various slip models indicated that the large slip occurred near the trench, it would be difficult to directly relate the large moment release with the second high-frequency sub-event near the coast. We estimated rupture speeds among the three sub-events to be 1.1-2.2 km/s, suggesting sub-shear ruptures. We speculated that the initial rupture started slowly from the hypocenter and propagated bilaterally toward the land and trench. The landward rupture propagation triggered the first sub-event and then the closely located second sub-event. After the second sub-event, the rupture propagated toward the south and triggered the third sub-event. These high-frequency sub-events correspond to three distinct asperities along the plate interface. The trenchward propagation ruptured the strongest asperity and released the largest moment near the trench.
Kumagai, H.; Pulido, N.; Fukuyama, E.; Aoi, S.
Rupture process of the 2011 Tohoku-Oki mega-thrust earthquake (M9.0) inverted from strong-motion data
NASA Astrophysics Data System (ADS)
We investigate the rupture process of the M9.0 Tohoku-Oki mega-thrust earthquake using the relatively low-frequency strong-motion records (0.01-0.125 Hz) observed at 36 K-NET and KiK-net stations, the epicentral distances of which range from 120 km to 400 km. The fault model is a rectangular plane, the length and width of which are 510 km along the Japan Trench and 210 km along subducting direction of the Pacific Plate, respectively. We perform the multi-time-window inversion analysis with a 30 � 30 km2 subfault. The derived slip model has one large slip area. This area extends from the region around the hypocenter to the shallow part of the fault plane and further to the north and south along the trench axis, located far off southern Iwate, Miyagi, and northern Fukushima prefectures. The seismic moment is 4.42 � 1022 Nm (Mw 9.0) and the maximum slip is 48 m. The slips near the coast are relatively small, except off Miyagi prefecture, which experienced a slip greater than 5 m. The shallow large slip area, which continuously ruptured from 60 s to 100 s after the initial break, radiated seismic waves rich in very-low-frequency content (<0.02 Hz). The rupture after 100 s propagating to the southern fault area, contributes to the distinct phases observed for Fukushima and Ibaraki prefectures. The relationship between the proposed rupture model and the feature of the acceleration waveforms is not straightforward and suggests the frequency dependency of the seismic wave radiation.
Suzuki, Wataru; Aoi, Shin; Sekiguchi, Haruko; Kunugi, Takashi
Simultaneous Estimation of Earthquake Source Parameters and Site Response from Inversion of Strong Motion Network Data in Kachchh Seismic Zone, Gujarat, India
NASA Astrophysics Data System (ADS)
Inversion of horizontal components of S-wave spectral data in the frequency range 0.1-10.0 Hz has been carried out to estimate simultaneously the source spectra of 38 aftershocks (Mw 2.93-5.32) of the 2001 Bhuj earthquake (Mw 7.7) and site response at 18 strong motion sites in the Kachchh Seismic Zone, Gujarat, India. The spatial variation of site response (SR) in the region has been studied by averaging the SR values obtained from the inversion in two frequency bands; 0.2-1.8 Hz and 3.0-7.0 Hz, respectively. In 0.2-1.8 Hz frequency band, the high SR values are observed in the southern part of the Kachchh Mainland Fault that had suffered extensively during the 2001 Bhuj Earthquake. However, for 3.0-7.0 Hz band, the area of Jurassic and Quaternary Formations show predominantly high SR. The source spectral data obtained from the inversion were used to estimate various source parameters namely, the seismic moment, stress drop, corner frequency and radius of source rupture by using an iterative least squares inversion approach based on the Marquardt-Levenberg algorithm. It has been observed that the seismic moment and radius of rupture from 38 aftershocks vary between 3.1x10^{13} to 2.0x10^{17} Nm and 226 to 889 m, respectively. The stress drop values from these aftershocks are found to vary from 0.11 to 7.44 MPa. A significant scatter of stress drop values has been noticed in case of larger aftershocks while for smaller magnitude events, it varies proportionally with the seismic moment. The regression analysis between seismic moment and radius of rupture indicates a break in linear scaling around 10^{15.3} Nm. The seismic moment of these aftershocks found to be proportional to the corner frequency, which is consistent for earthquakes with such short rupture length.
Dutta, U.; Mandal, P.
A study on the structure and precipitation of Morakot (2009) induced by the Central Mountain Range of Taiwan
NASA Astrophysics Data System (ADS)
The three-dimensional structures and ingredients leading to extremely heavy precipitation associated with the passage of Typhoon Morakot (2009) over the Central Mountain Range (CMR) of Taiwan are investigated. Using a numerical model, the track, track deflection, characteristic rainbands, and precipitation patterns and maxima are successfully reproduced after verification against observational data. The high-level outward flow of the secondary circulation around the eyewall is not very clear even during Morakot's strongest stage. In the control case, the eyewall collapses within 5 h after landfall that is closely associated with limited precipitation along the track after landfall. During the early stage of landfall, the deep convection on the windward (west) side of the CMR helps strengthening the secondary circulation. A quantitative comparison of total precipitable water, translation speed, and orographic lifting among 12 typhoons in recent years causing large accumulated rainfall in Taiwan shows that the abundant water vapor around Taiwan outweighs translation speed and orographic lifting in resulting in the record-breaking precipitation. It is found that the major processes leading to strong upward motion in the extremely heavy precipitation during 0000 UTC 8 August-0000 UTC 9 August are initiated by orographic lifting by CMR.
Huang, Yi-Chih; Lin, Yuh-Lang
Crustal deformation in Taiwan: Results from finite source inversions of six Mw > 5.8 Chi-Chi aftershocks
NASA Astrophysics Data System (ADS)
We inverted strong motion data for the finite source parameters of six large aftershocks of the 1999 Chi-Chi, Taiwan, earthquake to investigate seismogenic structure in Taiwan. For each event we derived a preferred model by testing different focal mechanisms, hypocenters, rupture velocities, and dislocation risetimes, as well as different combinations of stations in more than 1000 inversions. We documented how the fits between the waveforms and the corresponding synthetics deteriorated as the hypocenter and focal mechanism deviate from those of the preferred model. If the deviation in focal mechanisms and hypocenters is less than 20� and 5 km, respectively, we generally recovered 80% of the preferred model's synthetic waveform fit. Unlike the dislocation risetime, the rupture velocity used in the inversion had a strong influence on the waveform fits in this study. We also used the slip models to study fault geometry. Two of the aftershocks ruptured on the southern extension of the main shock slip area. One strike-slip aftershock nucleated within the basement but ruptured mainly within the overlying sedimentary strata, suggesting that seismogenic deformation in the basement can influence shallow structures. P axes of the derived models have azimuths consistent with current plate motion. Finally, GPS displacement derived from the six slip models can explain 80% of the postseismic deformation observed in the aftershock regions, indicating that studies of postseismic deformation must take into account the cumulative effects of large, shallow aftershocks.
Chi, Wu-Cheng; Dreger, Doug
B values and ??-?? seismic source models: Implications for tectonic stress variations along active crustal fault zones and the estimation of high-frequency strong ground motion
In this study the tectonic stress along active crustal fault zones is taken to be of the form ??(y) + ????p(x, y), where ??(y) is the average tectonic stress at depth y and ???? p(x, y) is a seismologically observable, essentially random function of both fault plane coordinates; the stress differences arising in the course of crustal faulting are derived from ????p(x, y). Empirically known frequency of occurrence statistics, moment-magnitude relationships, and the constancy of earthquake stress drops may be used to infer that the number of earthquakes N of dimension ???r is of the form N ?? 1/r2 and that the spectral composition of ????p(x, y) is of the form |????p(k)| ?? l/k2, where ????p(k) is the two-dimensional Fourier transform of ????p(x, y) expressed in radial wave number k. The y = 2 model of the far-field shear wave displacement spectrum is consistent with the spectral composition |????p(K)| ?? l/k2, provided that the number of contributions to the spectral representation of the radiated field at frequency f goes as (k/ko), consistent with the quasi-static frequency of occurrence relation N ?? 1/r2; K o is a reference wave number associated with the reciprocal source dimension. Separately, a variety of seismologic observations suggests that the ?? = 2 model is the one generally, although certainly not always, applicable to the high-frequency spectral decay of the far-field radiation of earthquakes. In this framework, then, b values near 1, the general validity of the y = 2 model, and the constancy of earthquake stress drops independent of size are all related to the average spectral composition of ???? p(x, y), |????p(k)| ?? l/k2. Should one of these change as a result of premonitory effects leading to failure, as has been specifically proposed for b values, it seems likely that one or all of the other characteristics will change as well from their normative values. Irrespective of these associations, the far-field, high-frequency shear radiation for the y = 2 model in the presence of anelastic attenuation may be interpreted as band-limited, finite duration white noise in acceleration. Its rms value, arms, is given by the expression arme = 0.85[21/2(2??)2/106] (????/pR)(f max/f0)1/2, where ???? is the earthquake stress drop, p is density, R is hypocentral distance, fo is the spectral corner frequency, and fmax is determined by R and specific attenuation 1/Q. For several reasons, one of which is that it may be estimated in the absence of empirically defined ground motion correlations, a rms holds considerable promise as a measure of high-frequency strong ground motion for engineering purposes. Copyright ?? 1979 by the American Geophysical Union.
Hanks, T. C.
Taiwan is a subtropical-tropical island characterized by high temperature and heavy rainfall. Intensive agricultural practices have served as a strong foundation for Taiwan's commercial and industrial economic miracle. In recent years, chemical pesticides and fertilizers were extensively applied to obtain higher crop yield. Overusing agrochemicals led to several agricultural problems such as poor cropping system. The excessive application of chemical
Shiuan-Yuh Chien; Chiu-Chung Young; Ching-Li Wang
Introduced Leishmaniasis on Taiwan.
National Technical Information Service (NTIS)
Leishmaniasis is not known to be indigenous to Taiwan but a number of imported cases of visceral as well as post-kala-azar dermal leishmaniasis have been seen. Only two autochthonous cases of cutaneous-subcutaneous diseases have been documented in aborigi...
J. H. Cross J. J. Gunning D. J. Drutz J. C. Lien
National Technical Information Service (NTIS)
This study was undertaken to make a clinical analysis of the physical conditions of snakebite on Taiwan, and to contribute to the improvement of medical treatment and prophylaxis of the snakebite. Eight hundred ninety-one cases of poisonous snakebite in t...
Y. Sawai C. S. Tseng
ERIC Educational Resources Information Center
A profile of Taiwan is sketched in this paper. Emphasis is placed on the nature, scope, and accomplishments of population activities in the country. Topics and sub-topics include: location and description of the country; population (size, growth patterns, age structure, urban/rural distribution, ethnic and religious composition, migration,�
Keeny, S. M.; And Others
Rock mass response to strong ground motion generated by mining induced seismic events and blasting observed at the surface of the excavations in deep level gold mines in South Africa
NASA Astrophysics Data System (ADS)
The strong ground motion generated by mining induced seismic events was studied to characterize the rock mass response and to estimate the site effect on the surface of the underground excavations. A stand-alone instruments, especially designed for recording strong ground motions, were installed underground at a number of deep level gold mines in South Africa. The instruments were recording data at the surface of the stope hangingwalls. A maximum value of 3 m/s was measured. Therefore data were compared to the data recorded in the solid rock by the mine seismic networks to determine the site response. The site response was defined as the ratio of the peak ground velocity measured at the surface of the excavations to the peak ground velocity inferred from the mine seismic data measured in the solid rocks. The site response measured at all mines studied was found to be 9 � 3 times larger on average. A number of simulated rockbursts were conducted underground in order to estimate the rock mass response when subjected to extreme ground motion and derive the attenuation factors in near field. The rockbursts were simulated by means of large blasts detonated in solid rock close to the sidewall of a tunnel. The numerical models used in the design of the simulated rockbursts were calibrated by small blasts taking place at each experimental site. A dense array of shock type accelerometers was installed along the blasting wall to monitor the attenuation of the strong ground motion as a function of the distance from the source. The attenuation of the ground motion was found to be proportional to the distance from the source following R^-1.1 & R^-1.7 for compact rock and R^-3.1 & R^-3.4 for more fractured rock close to the surface of the tunnel. In addition the ground motion was compared to the quasi-static deformations taking place around the underground excavations. The quasi-static deformations were measured by means of strain, tilt and closure. A good correspondence between the quasi-static deformations and seismic ground motion was found. During the blasting time and the subsequent seismic events the strain, tilt and closure show a rapid increase. Similar increase was observed during the strong seismic event. The deformations associated with a strong seismic event were described as 'fast' seismic events. Much of quasi-static deformations, however, occurred independently of the seismic events and was described as 'slow' or aseismic events.
Milev, Alexander; Durrheim, Ray; Ogasawara, Hiroshi
[Early missionary medicine in Taiwan].
Taiwan, as mainland China, first received modern medicine from Christian missionaries. Although Western medicine was introduced by the Dutch in the 17th century, it disappeared after their expulsion by Zheng Chenggong. It was not until 1865 when the British Presbyterian Church sent Dr. James Laidlow Maxwell to Taiwan to engage in medical and missionary work that Western medicine was able to take root in Taiwan. The last three decades of the 19th century were a key period in the development of modern medicine in Taiwan. This paper discusses three major figures in early missionary medicine in Taiwan, Dr. James Laidlow Maxwell, Rev. George Leslie Mackay, and Dr. David Landsborough and their contributions to the development of modern medicine in Taiwan. PMID:11613242
Kao, T; Ha, H
Further considerations of evaluation competencies in Taiwan.
A list of evaluator competencies (Stevahn, King, Ghere, & Minnema, 2005) was adapted to fit the Taiwanese context by Lee, Altschuld, & Lee (2012). It was studied as to how it generalized to a large sample in Taiwan. Likert and Fuzzy surveys with needs assessment formats (importance and competence) were mailed via random assignment to two groups of participants. The questions for the study were: do the modified competencies relate country-wide to Taiwan, did the investigation uncover training needs for evaluators, and were there convergent rating patterns across the two forms of the instrument? The results supported a fit of the modified competencies to the context and convergent validity was observed but strong competency needs were not apparent. Reasons for the findings and implications for future research are discussed. PMID:23856505
Lee, Yi-Fang; Altschuld, James W; Lee, Lung-Sheng Steven
The 2005 Ilan Plain (northeastern Taiwan) seismic crisis: a dike intrusion event associated with onland propagation of the Okinawa Trough
NASA Astrophysics Data System (ADS)
Northern Taiwan underwent mountain building in the early stage of the Taiwan orogeny but is now subjected to post-collisional crustal extension. Extension could be related to gravitational collapse or to the interaction with the Okinawa trough which lies offshore northeastern Taiwan. The Ilan Plain, northeastern Taiwan, which is bounded by the normal fault systems and filled up with thick Pliocene-Pleistocene sedimentary sequences, is one major zone where extension is taking place. On March 5, 2005 two earthquakes with about the same magnitude (ML=5.9) occurred there within 68 seconds and produced intense aftershocks activity recorded by Central Weather Bureau Seismic Network. We relocated the earthquake sequence by the three-dimension earthquake location algorithm with the newly published three-dimensional P- and S-wave velocity model, and determined the first-polarity focal mechanisms of the earthquake doublet. One major cluster of aftershocks which trends E-W and dips steeply to the south can be identified and picked up as a potential fault plane. The focal mechanisms of the two mainshocks are both pure normal and consistent with N-S strike. Static co- seismic deformation was additionally determined form GPS daily solutions at a set of continuous GPS stations and from strong-motion seismographs. These data show EW-SE extension at high angle to the fault plane, but the vertical displacements cannot be explained from a simple normal event double-couple mechanism. We present from elastic dislocation modeling that the geodetic data are best explained by tensile source with 28 mm of opening on a 13 km long fault extending from 1 to 13 km depth. We therefore interpret the crisis as the result of dike intrusion at the very tip of the Okinawa Trough, which is reasonably driven by back-arc spreading.
Lai, K.; Chen, Y.; Wu, Y.; Avouac, J.; Kuo, Y.; Wang, Y.; Chang, C.; Lin, K.
A multiple time window rupture model for the 1999 Chi-Chi earthquake from a combined inversion of teleseismic, surface wave, strong motion, and GPS data
NASA Astrophysics Data System (ADS)
We present the results of a comprehensive analysis of the rupture process of the 1999 Chi-Chi, Taiwan, earthquake using a broad array of seismic as well as geodetic data, spanning a very wide frequency band. Our results indicate that the rupture was quite smooth, with the slip concentrated in a wide arcuate region north of the epicenter with very little slip to the east or south. We found a moment of 3.3 � 1027 dyn cm, which is consistent with the long-period determinations for this earthquake. The rupture velocity is approximately 2.25 km/s and is quite uniform across the fault. We have tested both a single fault plane model as well as a composite fault model with a second E-W striking plane to the north of the rupture to improve the fit of the geodetic data. Overall, the differences in slip distribution between the two models are negligible, but the fit to the GPS data is significantly better for the composite model, which is thus our preferred solution. This model is similar to other rupture models as far as the large-scale features are concerned but differs for the smaller asperities that are present in other models but not as much in ours. These are usually poorly constrained, and with the use of the geodetic data we believe that there is little evidence for a significant amount of slip away from our main slip concentration.
Thio, H. K.; Graves, R. W.; Somerville, P. G.; Sato, T.; Ishii, T.
The National Space Program Office (NSPO) was established in 1991 to execute the space program in Taiwan. The first fifteen-year space program (1991-2006) consists of setting up infrastructure and carrying out three satellite programs (ROCSAT-1, ROCSAT-2 and ROCSAT-3). For the second fifteen-year program (2004-2018), NSPO will execute five major missions that include remote sensing satellites, broadband communication satellite, micro-satellites, international
L.-C. Lee
Using the first nationally representative birth cohort study in Taiwan, this paper examines the role that maternity leave policy in Taiwan plays in the timing of mothers returning to work after giving birth, as well as the extent to which this timing is linked to the amount of time mothers spend with their children and their use of breast milk versus formula. We found that the time when mothers returned to work coincided with the duration of guaranteed leave. In particular, mothers with a labor pension plan resumed work significantly earlier than mothers with no pension plan, and mothers with no pension plan returned to work significantly later than those with pension plans. The short leave of absence guaranteed under existing policies translated into mothers spending less time with their children and being more likely to exclusively use formula by 6 months after birth. In contrast, mothers who resumed work later than 6 months after birth were more likely to have not worked before birth or to have quit their jobs during pregnancy. Implications and recommendations for parental leave policy in Taiwan are discussed.
Feng, Joyce Yen; Han, Wen-Jui
Practical Applications of Low Cost Seismic Network for Producing Quick Shaking Map in Taiwan
NASA Astrophysics Data System (ADS)
Two major earthquakes of ML greater than 6.0 occurred in Taiwan in the first half of 2013. The vibrantly shakings brought landslides, falling rocks and casualties. This paper presents a seismic network developed by National Taiwan University (NTU) with 401 Micro-ElectroMechanical Systems (MEMS) accelerators. The network recorded high quality strong motion signals of the two events and produced delicate shaking maps within one minute after the earthquake occurrence. The high shaking regions of the intensity map produced by the NTU system precisely indicate the locations of damages and casualties. Equipping with the dense array of MEMS accelerometers, the NTU system is able to accommodate 10% signals loss from part of the seismic stations and maintains its normal functions for producing shaking maps. The system also has the potential to identify the direction of rupture which is one of the key indices to estimate possible damages. The low cost MEMS accelerator array shows its potential in real-time earthquake shaking map generation and damage avoidance.
Wu, Yih-Min
Broadband strong motion simulation coupling K-2 kinematic source model with empirical Green's functions: application to the 2009 L'Aquila earthquake
NASA Astrophysics Data System (ADS)
We perform 'blind' broadband ground-motion simulations using empirical Green's functions (EGF) summed up according to a k-2 kinematic source model. Source parameters (roughness degree of slip heterogeneity, nucleation point, rupture velocity) are defined as a priori random variables, so as to compute the expected median and variability of the ground-motion. The method is used to predict ground-motion of the 2009 L'Aquila earthquake (Mw = 6.3), one of the best recorded events in Europe. A large database of aftershocks is available, providing a large number of potential EGFs. Moreover the main shock and the aftershocks have been recorded at various distances from the epicenter, and hence simulations have been performed both in near-field and far-field conditions. We first selected aftershocks in the magnitude range 3.5 - 3.7, located approximately on the fault plane of the main shock, with a similar focal mechanism and with a high signal to noise ratio (> 3) in the frequency range of interest (0.2 Hz to 20 Hz). All these aftershocks (~15) can be considered as 'good' candidates for EGF ground-motion prediction. We then analyze how the choice of the EGF affect the simulation results. We also show that the use of several EGF distributed over the fault plane significantly improves the results in comparison to predictions performed using a single EGF, especially for the near source stations. Finally we analyze how different degree of a priori knowledge on the source parameters (fixed low frequency slip distribution, roughness degree of slip heterogeneity, rupture velocity, nucleation point) may affect the simulations. Comparison between synthetics and real data are shown in terms of Fourier amplitude spectra and response spectra.
Del Gaudio, Sergio; Causse, Mathieu; Festa, Gaetano
Strong Libraries, Strong Scores
ERIC Educational Resources Information Center
This article talks about the first-ever Texas Conference on School Libraries on April 6, 2005 that was attended by one hundred thirty-five school administrators and trustees. The miniconference, entitled Strong Libraries, Strong Scores, was held at the Austin Hilton, Austin, Texas during the Texas Library Association's Annual Conference and was�
Gray, Carlyn
NASA Astrophysics Data System (ADS)
Taiwan's current and future space programs are briefly introduced in this paper. The National Space Organization (NSPO) in Taiwan has successfully carried out three satellite programs (FORMOSAT-1, 2, &3) since its establishment in 1991. FORMOSAT-1 is a scientific satellite performing three scientific experiments for measuring the density, velocity and temperature of ionospheric plasmas, taking the ocean color image, and conducting Ka-band communication experiments. Equipped with a 2m ground resolution remote sensing instrument, FORMOSAT-2 operates in a sun-synchronous orbit with revisit time equal to one day. This unique feature of the daily revisit capability is significantly useful for post disaster assessment and environmental monitoring. FORMOSAT-2 also carries a scientific payload "Imager of Sprites and Upper Atmospheric Lightning (ISUAL)". ISUAL provides the world's first long-term satellite observations on the lighting phenomenon in the earth's upper atmosphere. FORMOSAT-3 is a constellation of six micro-satellites to collect atmospheric and ionospheric data for weather prediction and for climate, ionosphere, and geodesy research. FORMOSAT-3 has demonstrated the ability to significantly increase the accuracy of weather forecasting by utilizing the GPS Radio Occultation (GPS-RO) technique. Currently, NSPO is pursuing the follow-on space missions of FORMOSAT-5 and FORMOSAT-7. FORMOSAT-5 will be the first to utilize a CMOS detector on a high-resolution earth-observation camera. FORMOSAT-7 is a joint mission of Taiwan/US to deploy a 12-satellite constellation operational system to provide dense and timely GNSS RO data to the global communities for real-time weather forecast as well as space science research.
Lee, Lou-Chuang; Chang, Guey-Shin; Ting, Nan-Hong
Seismic Safety Margins Research Program, Phase I. Project II: seismic input. Compilation, assessment and expansion of the strong earthquake ground motion data base
A catalog has been prepared which contains information for: (1) world-wide, ground-motion accelerograms, (2) the accelerograph sites where these records were obtained, and (3) the seismological parameters of the causative earthquakes. The catalog is limited to data for those accelerograms which have been digitized and published. In addition, the quality and completeness of these data are assessed. This catalog is unique because it is the only publication which contains comprehensive information on the recording conditions of all known digitized accelerograms. However, information for many accelerograms is missing. Although some literature may have been overlooked, most of the missing data has not been published. Nevertheless, the catalog provides a convenient reference and useful tool for earthquake engineering research and applications.
Crouse, C B; Hileman, J A; Turner, B E; Martin, G R
Numerical studies on Heavy Rainfall Events over Northern Taiwan in Mei-Yu Season
NASA Astrophysics Data System (ADS)
Two unusual heavy rainfall events occurred in northern Taiwan from late evening of 11 June to the early morning of 12 June 2012 and late evening of 2 June to the early morning of 3 June 1984. In a few hours, more than 400 mm rainfall were recorded over northwestern Taiwan in these two events. The mechanisms for the commencement and maintenance of this localized heavy rainfall events over northern Taiwan are investigated using the NCEP global grid data, satellite imageries, radar reflectivities, and simulations from the Weather Research and Forecast (WRF) model. These events occurred under favorable large-scale environment that included: upper-level divergence; low-level high equivalent potential temperature; low level of free convection (LFC); and subsynoptic-scale ascending motion over the northern Taiwan Strait and northern Taiwan. In the late night of 2 June, the main heavy rainfall area is simulated to the southeast of the low-level windshift line associated with a trough axis, which is located in the southeastern China coast. The simulated heavy rainfall area moves eastward toward northeastern Taiwan Strait and the northwestern coast of Taiwan as the windshift line continues to propagate eastward. The heavy convective rainfall is enhanced in the eastern Taiwan Strait by orographic blocking where the prevailing southwesterly wind within the Taiwan Strait converges with the orographically deflected flow with a southerly wind component off the western/northwestern Taiwan coast. As the simulated convective area continues to move toward northern Taiwan, it intensifies in a localized low-level convergence area over the northeastern Taiwan Strait and northwestern coast of Taiwan where a barrier jet along the coast converges with the northwesterly winds behind the surface front. Furthermore, in the early morning of 3 June, the simulated rainfall is heavier where the barrier jet encounters the leading edge of the cold pool caused by rain evaporative cooling. As the convective systems drift inland, the orographic lifting of the pre-frontal southwesterly flow helps to produce higher simulated rainfall intensity in the southern slopes of the Taipei Basin. The simulated daily accumulated rainfall over the Taipei Basin and northwestern coast of Taiwan is about 200 and 400 mm, respectively, about 50 mm less than observed. In an experiment without Taiwan's topography (the NT run), the simulated rainfall intensity over the northern Taiwan Strait and the northwestern coast of Taiwan is much less. In contrast to the control run, despite the presence of favorable large-scale settings, no convective systems move to the northern part of Taiwan from the northern Taiwan Strait in the NT run without heavy rainfall simulated over northern Taiwan. Two events will be comparatively investigated by WRF on the formation and maintainence of heavy rainfall in Mai-Yu season.
Lin, Pay-Liam
Gravity features of the mud diapirs off southwest Taiwan
NASA Astrophysics Data System (ADS)
Both the overpressure and buoyancy phenomena are generally used to account for the formation of submarine mud diapirs. According to the distribution of the mud diapirs and structural features, the compressive stress should play an important role on the formation of the mud diapirs in the offshore area of southwest Taiwan. Onland Taiwan, the Tainan and Chungchou anticlinal structures (associated with mud diapirs) reveal positive gravity anomalies. The mud diapirs off SW Taiwan are considered to be more active than onshore diapirs. However, the gravity nature of the submarine mud diapirs is not clear. In 2012 and 2013, we have collected shipboard gravity data by using R/V Ocean Researcher I in the offshore area of southwest Taiwan. Several NW-SE trending gravity profiles show a sharp drop across the Kaoping Canyon. By removing the gravimetric effect from the water-sediment interface, we find that the density contrasts of the mud diapirs with respect to the surrounding strata are generally positive. The results seem conflict with the buoyant force that triggers the upward motion of the mud diapirs. In this study, we will show some possible mechanisms to explain the gravity nature of the submarine mud diapirs.
Doo, W.; Hsu, S.; Huang, Y.; Chen, S.
Industry Sector Analysis, Taiwan: Cosmetics.
National Technical Information Service (NTIS)
The market survey covers the cosmetics market in Taiwan. The analysis contains statistical and narrative information on projected market demand, end-users; receptivity of Taiwanese consumers to U.S. products; the competitive situation, and market access (...
Subsurface imaging, TAIGER experiments and tectonic models of Taiwan
NASA Astrophysics Data System (ADS)
The seismicity, deformation rates and associated erosion in the Taiwan region clearly demonstrate that plate tectonic and orogenic activities are at a high level. Major geologic units can be neatly placed in the plate tectonic context, albeit critical mapping in specific areas is still needed, but the key processes involved in the building of the island remain under discussion. Of the two plates in the vicinity of Taiwan, the Philippine Sea Plate (PSP) is oceanic in its origin while the Eurasian Plate (EUP) is comprised partly of the Asian continental lithosphere and partly of the transitional lithosphere of the South China Sea basin. It is unanimously agreed that the collision of PSP and EU is the cause of the Taiwan orogeny, but several models of the underlying geological processes have been proposed, each with its own evolutionary history and implied subsurface tectonics. TAIGER (TAiwan Integrated GEodynamics Research) crustal- and mantle-imaging experiments recently made possible a new round of testing and elucidation. The new seismic tomography resolved structures under and offshore of Taiwan to a depth of about 200 km. In the upper mantle, the steeply east-dipping high velocity anomalies from southern to central Taiwan are clear, but only the extreme southern part is associated with seismicity; toward the north the seismicity disappears. The crustal root under the Central Range is strongly asymmetrical; using 7.5 km/s as a guide, the steep west-dipping face on the east stands in sharp contrast to a gradual east-dipping face on the west. A smaller root exists under the Coastal Range or slightly to the east of it. Between these two roots lies a well delineated high velocity rise spanning the length from Hualien to Taitung. The 3-D variations in crustal and mantle structures parallel to the trend of the island are closely correlated with the plate tectonic framework of Taiwan. The crust is thickest in the central Taiwan collision zone, and although it thins toward the south, the crust is over 30 km thick over the subduction in the south; in northern Taiwan, the northward subducting PSP collides with Taiwan and the crust thins under northern Taiwan where the subducting indenter reaches 50 km in depth. The low Vp/Vs ratio of around 1.6 at a mid-crustal depth of 25 km in the Central Range indicates that current temperatures could exceed 700 �C. The remarkable thickening of the crust under the Central Range, its rapid uplift without significant seismicity, its deep exhumation and its thermal state contribute to make it the core of orogenic activities on Taiwan Island. The expanded network during the TAIGER deployment captured broadband seismic data yielding enhanced S-splitting results with mainly SKS/SKKS data. The polarization directions of the fast S-waves follow very closely the structural trends of the island, supporting the concept of a vertically coherent Taiwan orogeny in the outer few hundred kilometers of the Earth.
Wu, Francis T.; Kuo-Chen, H.; McIntosh, K. D.
Application of Probabilistic Seismic Hazard Assessment (PSHA) to Taiwan
NASA Astrophysics Data System (ADS)
In this study we assess the probabilistic seismic hazard for the Taiwan region. For this propose, the information on tectonic setting, geology, geomorphology, earthquake catalog, and ground motion attenuation is integrated. The treatment of seismogenic sources is based on several categories, which are from shallow crust regions, deep crust regions, crustal active faults, subduction intraslabs, and subduction interfaces. By further considering ground motion prediction equations for different types of sources and site conditions, probabilistic seismic hazard can be assessed. The obtained high hazards can mainly be contributed by the crustal active faults with short recurrence intervals. Thus, higher hazards are evaluated along the active faults in the Coastal Plain and the Longitudinal Valley. In northern Taiwan, by contrast, a low hazard level is obtained. It corresponds to relative inactive tectonics and faults in this region and its vicinity. Since this assessment is widely applied for each administrative region in Taiwan, when the information of vulnerability and exposure is further considered, probabilistic seismic risk map could be assessed. The result would be a benefit to decision-makers and public officials for seismic hazard mitigation.
Lin, P.; Cheng, C.; Hsieh, P.; Yen, Y.; Chan, C.
Feasibility study of a nation-wide Early Warning System: the application of the EEW software PRESTo on the Italian Strong Motion Network (RAN)
NASA Astrophysics Data System (ADS)
The past two decades have witnessed a huge progress in the development, implementation and testing of Earthquakes Early Warning Systems (EEWS) worldwide, as the result of a joint effort of the seismological and earthquake engineering communities to set up robust and efficient methodologies for the real-time seismic risk mitigation. The leading experience of the operational early warning system implemented by the Japan Meteorological Agency showed the effectiveness of a combined onsite and network-based approach to rapidly broadcast the rapid warning after a potential damaging earthquake. At the nation-wide scale, the Japanese system makes use of real-time data streamed by the extremely dense accelerograph array (about 1000 seismic instruments) deployed across Japan. With more than 750 accelerometric stations installed over all the active seismic zones, target cities and strategic infrastructures, Italy has the potential for a nation-wide early warning system, although the communication network and data sharing must be expanded and improved. A significant number of these stations are nodes of the RAN (Italian Accelerometric Network) managed by the Italian national emergency management department (Dipartimento della Protezione Civile, DPC), whose data are used for emergency response services. In the framework of the REAKT-Strategies and tools for Real Time Earthquake RisK ReducTion FP7 European project, the AMRA-RISSCLab group is engaged in a feasibility study on the implementation of the EEW software PRESTo earthquake early warning platforms on the Italian accelerometric network (RAN) PRESTo (PRobabilistic and Evolutionary early warning SysTem) is a highly configurable and easily portable platform for Earthquake Early Warning. The system processes the live accelerometric streams from the stations of a seismic network to promptly provide probabilistic and evolutionary estimates of location and magnitude of detected earthquakes while they are occurring, as well as shaking prediction at the regional scale. Alarm messages containing those parameters can reach target sites before the destructive waves, enabling automatic safety procedures. The earthquake location is obtained by an evolutionary, probabilistic approach that uses information from both triggered and not-yet-triggered stations at each time step. Magnitude estimation is based on a Bayesian approach that uses the peak displacement measured on short 2-4 second windows of P- and S-waves signal. Peak ground motion is estimated at target sites by GMPEs using location and magnitude. The performance of the potential EW system at the national scale has been investigated through simulated earthquake scenarios using real-data from several M 5-6 earthquakes recorded by the network RAN. Furthermore, a statistical approach has been implemented considering a nation-wide grid of synthetic sources, the same grid which is used to derive the seismic hazard map in Italy. By considering a virtual testing period of 50 years, each grid's node is considered as a seismic source capable of generating a sequence of earthquakes with magnitude varying according the seismogenic zones properties to which it belongs. Then, the EW algorithm, PRESTo, is run on the sequences of synthetic data created for each of the grid's points considering the present-day RAN configuration, and network performance in terms of lead-time, errors in event location and magnitude determination is computed for the tested sources.
Zollo, Aldo; Picozzi, Matteo; Elia, Luca; Martino, Claudio; Brondi, Piero; Colombelli, Simona; Emolo, Antonio; Festa, Gaetano; Marcucci, Sandro
Taiwan: An energy sector study
A study on the economy of Taiwan, with special reference to the energy sector, revealed the following: Taiwan's rapid export-driven economic growth in the 1970s and 1980s has earned them the rank of ''Newly Industrialized Countries.'' Coal reserves measure less than 1 billion tons, and annual output has declined to below 2 million tons per year. Marginal amounts of crude are produced. Natural gas resources have been exploited both on- and offshore, through production amounts to little more than 1 billion cubic meters per year. Domestic hydrocarbon production is forecast to decline. Taiwan prssesses an estimated 5300 mW of exploitable hydropower capacity, of which 2564 mW had been installed by 1986. Taiwan has undertaken a massive program of nuclear power construction in response to the rapid rise in oil prices during the 1970s. Energy demand has risen an average of 9.0 percent per year since 1954, while real GNP has grown 8.6 percent per year. Sine 1980, oil has provided a lower share of total energy demand. Oil demand for transport has continued to grow rapidly. Declining production of domestic natural gas has led Taiwan to initiate LNG imports from Indonesia beginning in 1990. Coal has regained some of its earlier importance in Taiwan's energy structure. With declining domestic production, imports now provide nearly 90 percent of total coal demand. Taiwan is basically self-sufficient in refining capacity. Energy demand is expected to grow 5.4 percent per year through the yeat 2000. With declining output of domestic resources, energy dependency on imports will rise from its current 90 percent level. Government policy recognizes this external dependency and has directed it efforts at diversification of suppliers. 18 refs., 11 figs., 40 tabs.
Johnson, T.; Fridley, D.; Kang, Wu
Surface waves in the western Taiwan coastal plain from an aftershock of the 1999 Chi-Chi, Taiwan, earthquake
Significant surface waves were recorded in the western coastal plain (WCP) of Taiwan during the 1999 Chi-Chi, Taiwan, earthquake and its series of aftershocks. We study in detail the surface waves produced by one aftershock (20 September 1999, 18hr 03m 41.16sec, M 6.2) in this paper. We take the Chelungpu-Chukou fault to be the eastern edge of the WCP because it marks a distinct lateral contrast in seismic wave velocities in the upper few kilometers of the surface. For many records from stations within the WCP, body waves and surface waves separate well in both the time domain and the period domain. Long-period (e.g., >2 sec) ground motions in the plain are dominated by surface waves. Significant prograde Rayleigh wave particle motions were observed in the WCP. The observed peak ground velocities are about 3-5 times larger than standard predictions in the central and western part of the plain. Observed response spectra at 3 sec, 4 sec, and 5 sec at the center of the plain can be 15 times larger than standard predictions and 10 times larger than the predictions of Joyner (2000) based on surface wave data from the Los Angeles basin. The strong surface waves were probably generated at the boundary of the WCP and then propagated toward the west, largely along radial directions relative to the epicenter. The geometry of the boundary may have had a slight effect on propagation directions of surface waves. Group velocities of fundamental mode Rayleigh and Love waves are estimated using the multiple filter analysis (MFA) technique and are refined with phase matched filtering (PMF). Group velocities of fundamental mode surface waves range from about 0.7 km/sec to 1.5 km/sec for the phases at periods from 3 sec to 10 sec. One important observation from this study is that the strongest surface waves were recorded in the center of the plain. The specific location of the strongest motions depends largely on the period of surface waves rather than on specific site conditions or plain structures. Accordingly, we conjecture that surface waves could be generated in a wide area close to boundaries of low-velocity sedimentary wave guides. In the case studied in this article the area can be as wide as 30 km (from the Chelungpu fault to the center of the plain). Surface waves converted by P and S waves at different locations would overlap each other and add constructively along their propagation paths. As a result, the surface waves would get stronger and stronger. Beyond a certain distance to the boundary, no more surface waves would be generated. Consequently, no more local surface waves would be superimposed into the invasive surface waves, and the surface waves would tend to decay in amplitude with distance.
Wang, G. -Q.; Tang, G. -Q.; Boore, D. M.; Van Ness, Burbach, G.; Jackson, C. R.; Zhou, X. -Y.; Lin, Q. -L.
Water mass and throughflow transport variability in the Taiwan Strait
Variability of water mass and throughflow transport in the Taiwan Strait are analyzed using strait-wide conductivity-temperature-depth (1985�2003) and sectional acoustic Doppler current profiler (1999�2001) data. Results from a cluster analysis, temperature-salinity diagrams, and direct transport calculations indicate that the strong northeast monsoon drives the brackish Mixed China Coastal Water into the northern strait and hinders the northward intruded saline Kuroshio
Sen Jan; David D. Sheu; Huei-Ming Kuo
Ophthalmic plastic and orbital surgery in Taiwan.
We describe in this paper the current status of ophthalmic plastic and orbital surgery in Taiwan. Data were collected from the Bureau of National Health Insurance of Taiwan, the Bulletin of the Taiwan Ophthalmic Plastic and Reconstructive Society, and the Statistics Yearbook of Practicing Physicians and Health Care Organizations in Taiwan by the Taiwan Medical Association. We ascertained that 94 ophthalmologists were oculoplastic surgeons and accounted for 5.8% of 1621 ophthalmologists in Taiwan. They had their fellowship training abroad (most ophthalmologists trained in the United States of America) or in Taiwan. All ophthalmologists were well trained and capable of performing major oculoplastic surgeries. The payment rates by our National Health Insurance for oculoplastic and orbital surgeries are relatively low, compared to Medicare payments in the United States. Ophthalmologists should promote the concept that oculoplastic surgeons specialize in periorbital plastic and aesthetic surgeries. However, general ophthalmologists should receive more educational courses on oculoplastic and cosmetic surgery. PMID:24898627
Hsu, Chi-Hsin; Lin, I-Chan; Shen, Yun-Dun; Hsu, Wen-Ming
Two forms of detrital monazite are known in offshore bars in southwestern Taiwan: a yellow-green to colorless form and an unusual but abundant pelletlike form, generally black but also colored gray or brown. These black pellets, which are about 160 by 200 microns in size, are composed of fine-grained monazite crystals from 2 to 20 microns in size. The pellets are associated with highly variable amounts of discrete grains of detrital quartz, rutile, amphibole, tourmaline, and other minerals. Intergrown with the monazite are quartz, a cerium oxide mineral, chlorite, sulfides, and other minerals. Opaqueness of the pelletlike monazite is due principally to the cryptocrystalline nature of part of the monazite; only a small part of the opaqueness can be attributed to opaque inclusions. The black pelletlike monazite lacks thorium and has a high content of europium. In this respect, as in color, shape, size, and inclusions, the pelletlike monazite differs from the yellow-green detrital monazite. Despite the fact that they occur together in the littoral placers, they appear to have had different origins. The yellow-green monazite originated as an accessory mineral in plutonic rocks and has accumulated at the coast through erosion and transport. The origin of the pelletlike monazite is as yet unknown, but it is here inferred that it originated in unconsolidated coastal plain sediments through migration of cerium from the detrital monazite during weathering, and of the intermediate weight mobile rare earths from clay minerals during diagenesis. Possibly these pelletlike grains are detrital particles formed through erosion and transport from originally larger aggregates cemented by diagenetic monazite.
Matzko, J. J.; Overstreet, W. C.
International Benchmarking with the Best Universities: Policy and Practice in Mainland China and Taiwan
ERIC Educational Resources Information Center
With a strong conviction to enhance their global competitiveness, governments across different parts of the world have tried various means to promote the ranking of their universities in the global university leagues. With a strong determination to do better in such global ranking exercises, universities in mainland China and Taiwan have attempted�
Mok, Ka Ho; Chan, Ying
Fault-plane Identification and Focal Mechanism of the 2003 Chengkung Earthquake Sequence, at East Taiwan
NASA Astrophysics Data System (ADS)
Two subduction systems are taken place around Taiwan Island respectively to the north and to the south. In between, the arc-continent collision proceeds at east Taiwan along the Longitudinal Valley fault. The Chengkung Earthquake, MW 6.5 December 10 2003 at the southern part of the Longitudinal Valley fault, is a typical thrust reflecting release of stress/strain accumulated in the eastern collision framework. Such earthquake sequence contains a seismicity distribution roughly covered a region of 40 km by 40 km, which compose of a thrust fault dipping to the east. According to the focal mechanism of the main shock and the spatial distribution of aftershocks, the mainly crustal movement in the Chengkung earthquake can therefore be recognized as a rupturing with an east-dip plane and thrusting toward the west. However, 15 larger aftershocks occurred 7 days after the main shock showed a more complicated tectonic setting around this area. In the offshore area, three aftershocks illustrated normal-fault-type deformation, which is rarely observed in this area. On land, the larger aftershocks exhibited oblique thrust deformation along the Longitudinal Valley fault. In order to better understand the seismotectonic setting in this earthquake, a waveform inversion was applied to refine the focal mechanism solutions and identify the fault plane from one or multiple seismic recordings at short epicentral distance. Kanamori et al., (1990) and Singh et al., (1997) showed clear examples of local events for which source parameters could be well constrained by using near-field waves, even with a single station. However, when surface ruptures are not observed, as in the case of too small events or blind faults, the fault plane may be undetermined. The method used in this study includes the effect of source finiteness directly in the inversion process, allowing us to invert sparse, near-field data for focal mechanism and fault plane determination simultaneously. Seven parameters, including the strike, dip, rake, and dislocation, were explored with a grid search and minima of the misfit error between the observed and calculated seismograms. The seismograms considered here are in displacement integrated from three-component strong-motion record, organized by the Central Weather Bureau of Taiwan. We have identified three groups of aftershocks showing nearly identical focal mechanisms in the Chengkung sequence, which have initially compiled by the BATS (Broadband Array in Taiwan for seismology), Academia Sinica of Taiwan. Each of these groups have been examined their spatial attitudes of fault plane and refined their focal mechanisms. Our results show a segmented rupture at the southern part of the Longitudinal Valley fault, and a deformation accommodation as function of space can be inferred in the Chengkung sequence. In comparison with the historical earthquake taken place in the late 1951 at the almost location, the Chengkung sequence is probably the reactivated rupture along the same fault segment, suggesting that the temporal and spatial rupture pattern was repeated.
Chang, T.; Delouis, B.
Active Extensional Structures Discovered by the Airborne LiDAR Mapping in the Tatun Volcanic Region, Taiwan
NASA Astrophysics Data System (ADS)
Complex tectonic deformation is present in northern Taiwan where the Philippine Sea plate is subducting under the Eurasian plate and the Okinawa trough is opening to the east. The Tatun volcanic region and the Taipei metropolitan basin are considered the products resulted from such complex tectonic environment. Furthermore, contractional deformation was prevailed in the earlier stage, as evidenced by several major thrust faults truncating the Tertiary strata. However, the expected nowadays extensional deformation is not fully characterized, for example, the Shanchiao fault bounding the western Taipei basin and its northern extension into the Tatun volcanic region. Based on industrial seismic profiles, it appeared that several well developed normal faults reactivated pre-existing thrust faults offshore northern Taiwan. These normal faults likely extend into the land where the Tatun volcanics erupted through and covered on the Tertiary strata. It is our intentions to better inspect the deformational pattern existing within the Tatun volcanic region where forests dominate on the surface making field investigation difficult. In this study we apply high-resolution airborne LiDAR-derived digital terrain model to characterize possible joints, fractures, and faults in the Tatun volcanic region. The LiDAR-derived DTM was processed so that bare ground is revealed using virtual removal of forests. The derived 2-m DTM was then examined to map out topographic features possibly resulted from the linear geologic structures. We discovered clear distribution and pattern of the joints and fractures in the Tatun volcanic region for the first time. The mapped structural patterns reveal strong evidence for regional extensional deformation in northern Taiwan, especially within the Tatun volcanic region. We also uncovered branches of normal faults extending possibly from the Shanchiao fault into the Tatun volcanic region. The discovered normal fault, perhaps active, cut across flat regions with averaging 3.3 meters in displacement. A field outcrop was found which contains fault gouge and striations indicating normal and strike-slip in motion. This further supports that the extensional deformation is young and an ongoing process in northern Taiwan, and that the region may produce significant earthquakes through such mechanism.
Chan, Y.; Chang, K.; Chen, R.; Lee, J.; Hsieh, Y.
Blood Parasites of Taiwan Birds.
National Technical Information Service (NTIS)
Blood films were examined from 1477 birds of Taiwan (193 species, 49 families in 15 orders). Haemoproteus Kruse was by far the commonest parasite, with Leucocytozoon Danilewski a not very close second. It is probable that some of the Haemoproteus infectio...
R. D. Manwell C. S. Allen R. E. Kuntz
Kindergartener's Technology Education in Taiwan.
ERIC Educational Resources Information Center
According to the American Association for Advancement of Sciences, the National Academy of Engineering, and the International Technology Education Association (ITEA) and its Technology for All Americans Project (TfAAP), technology education should begin in kindergarten. Educators in Taiwan have also advocated beginning technology education in�
Lai, Chun-Chin
Slow strain variations in Taiwan
Taiwan is located along the boundary between the Philippine Sea plate and the Eurasian plate, one of the most active plate boundaries in the world. The oblique collision between these two plates drives the mountain building and high seismic activity in this area. More than 300 permanent GPS stations are operating, about 1 site per 120 km2. The typical shorting
C. Liu; J. C. Hu; C. Y. Chen; A. T. Linde; I. S. Sacks
The 5 September 2012 Nicoya, Costa Rica Mw 7.6 earthquake rupture process from joint inversion of high-rate GPS, strong-motion, and teleseismic P wave data and its relationship to adjacent plate boundary interface properties
NASA Astrophysics Data System (ADS)
On 5 September 2012, a large thrust earthquake (Mw 7.6) ruptured a densely instrumented seismic gap on the shallow-dipping plate boundary beneath the Nicoya Peninsula, Costa Rica. Ground motion recordings directly above the rupture zone provide a unique opportunity to study the detailed source process of a large shallow megathrust earthquake using very nearby land observations. Hypocenter relocation using local seismic network data indicates that the event initiated with small emergent seismic waves from a hypocenter ~10 km offshore, 13 km deep on the megathrust. A joint finite-fault inversion using high-rate GPS, strong-motion ground velocity recordings, GPS static offsets, and teleseismic P waves reveals that the primary slip zone (slip > 1 m) is located beneath the peninsula. The rupture propagated downdip from the hypocenter with a rupture velocity of ~3.0 km/s. The primary slip zone extends ~70 km along strike and ~30 km along dip, with an average slip of ~2 m. The associated static stress drop is ~3 MPa. The seismic moment is 3.5 � 1020 Nm, giving Mw = 7.6. The coseismic large-slip patch directly overlaps an onshore interseismic locked region indicated by geodetic observations and extends downdip to the intersection with the upper plate Moho. At deeper depths, below the upper plate Moho, seismic tremor and low-frequency earthquakes have been observed. Most tremor locates in adjacent areas of the megathrust that have little coseismic slip; a region of prior slow slip deformation to the southeast also has no significant coseismic slip or aftershocks. An offshore locked patch indicated by geodetic observations does not appear to have experienced coseismic slip, and aftershocks do not overlap this region, allowing the potential for a comparable size rupture offshore in the future.
Yue, Han; Lay, Thorne; Schwartz, Susan Y.; Rivera, Luis; Protti, Marino; Dixon, Timothy H.; Owen, Susan; Newman, Andrew V.
Taiwan's Aquaculture: A U.S. Feed Materials Perspective,
National Technical Information Service (NTIS)
Taiwan's shrimp farms have been hit hard this year by a variety of problems, primarily disease and drought. Recently the American Institute in Taiwan (AIT) reported that Taiwan's crop of black tiger prawns (Penaeus monodon) is suffering from high mortalit...
R. B. Sheeks
The network structure of big business in Taiwan
This paper takes a network approach to understanding ownership patterns and director interlocks in Taiwan. In particular,\\u000a this paper analyzes ties among Taiwan�s top 200 publicly listed companies in 1990 and 2000. The speed of change in Taiwan�s\\u000a economic organization during the period has been striking. Not only have the identities of many of Taiwan�s largest firms\\u000a changed, there seems
Jonathan Brookfield
... people traveling by car, train, airplanes and especially boats. Motion sickness can start suddenly, with a queasy ... motion sickness. For example, down below on a boat, your inner ear senses motion, but your eyes ...
Queering Taiwan: in search of nationalism's other.
This article deals with the formation of Taiwan�s homosexual cultural politics in the 1990s, the impact and implications of which are yet to be examined within the larger context of Taiwan�s cultural and political development and ethnic relationships. It is argued that the rise of this cultural politics is both a reflection and a source of a growing sense of identity crisis on the island. By examining the configurations of �queer� in various discursive domains, this interdisciplinary study seeks to delineate the cross-referencing ideological network of this cultural movement and its entanglement with the complexity of Taiwan�s nationalism. At the same time, to the extent that this movement tends to present itself as a radical politics from a privileged epistemological and cultural standpoint, this claimed radicalism is also scrutinized for its problematics and ironies. PMID:21966703
Chen, Li-fen
Arsenic and Humic Substances in Alluvial Aquifers of Bangladesh and Taiwan: A Comparative Study
NASA Astrophysics Data System (ADS)
Humic substances in groundwater samples from the arsenicosis area in Bangladesh, northern Taiwan and the Blackfoot disease (BFD) area in southwestern Taiwan were characterized by Fluorescence Spectroscopy (FS), and Fourier Transform Infrared Spectroscopy (FTIR) analyses. As, Mn, Fe, Sr, Se levels in these groundwaters were measured by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). Major ions and selected water parameters including pH, electrical conductivity (EC), oxidation reduction potential (ORP), and dissolved oxygen (DO) were also determined. Groundwater As concentration ranges from 1.4 to 140 ?g/L in the alluvial aquifers located in the Chapai-Nawabganj district of Bangladesh. As levels in groundwater ranges from 0.5 to 560 ?g/L in the Ilan Plain of northern Taiwan. Geothermal waters in the Beitou hot springs contain high concentrations of inorganic As (up to 3,975 ?g/L); geothermal activity is likely responsible for the significant discharge of arsenic to the downstream Kwandu Plain. As levels in the BFD area of southwestern Taiwan ranges from 25 ?g/L to 967 ?g/L. Interestingly, groundwater arsenic in the BFD area of southwestern Taiwan correlates positively with strong fluorescence (maximum relative fluorescence intensity upto 495) and the content of humic substances. In contrast, As-rich groundwaters from Chapai-Nawabganj district of Bangladesh and northern part of Taiwan generally have relatively low content of humic substances with weak fluorescence (maximum relative fluorescence intensity upto 65 and 121, respectively). Moreover, results of FTIR analysis show that humic substances extracted from water samples of the Taiwan BFD area contain phenolic and amines groups of humic substances, which tend to form organo-metal complexes with As and other trace elements. High levels of As and humic substances probably play a critical role in causing the Black foot disease in Chia-Nan plain of southwestern Taiwan.
Reza, A.; Jean, J.; Lee, M.
Current situation and industrialization of Taiwan nanotechnology
Nanotechnology is projected to be a very promising field, and the impact of nanotechnology on society is increasingly significant\\u000a as the research funding and manufactured goods increase exponentially. A clearer picture of Taiwan�s current and future nanotechnology\\u000a industry is an essential component for future planning. Therefore, this investigation studies the progress of industrializing\\u000a nanotechnology in Taiwan by surveying 150 companies.
Hsin-Ning Su; Pei-Chun Lee; Min-Hua Tsai; Kuo-Ming Chien
Calibration of PS09, PS10, and PS11 trans-Alaska pipeline system strong-motion instruments, with acceleration, velocity, and displacement records of the Denali fault earthquake, 03 November 2002
In September, 2003, the Alyeska Pipeline Service Company (APSC) and the U.S. Geological Survey (USGS) embarked on a joint effort to extract, test, and calibrate the accelerometers, amplifiers, and bandpass filters from the earthquake monitoring systems (EMS) at Pump Stations 09, 10, and 11 of the Trans-Alaska Pipeline System (TAPS). These were the three closest strong-motion seismographs to the Denali fault when it ruptured in the MW 7.9 earthquake of 03 November 2002 (22:12:41 UTC). The surface rupture is only 3.0 km from PS10 and 55.5 km from PS09 but PS11 is 124.2 km away from a small rupture splay and 126.9 km from the main trace. Here we briefly describe precision calibration results for all three instruments. Included with this report is a link to the seismograms reprocessed using these new calibrations: http://nsmp.wr.usgs.gov/data_sets/20021103_2212_taps.html Calibration information in this paper applies at the time of the Denali fault earthquake (03 November 2002), but not necessarily at other times because equipment at these stations is changed by APSC personnel at irregular intervals. In particular, the equipment at PS09, PS10, and PS11 was changed by our joint crew in September, 2003, so that we could perform these calibrations. The equipment stayed the same from at least the time of the earthquake until that retrieval, and these calibrations apply for that interval.
Evans, John R.; Jensen, E. Gray; Sell, Russell; Stephens, Christopher D.; Nyman, Douglas J.; Hamilton, Robert C.; Hager, William C.
Noise in GPS position time series from Taiwan
NASA Astrophysics Data System (ADS)
Position time series of 393 continuous GPS (CGPS) stations with durations of 5-10 years are generated and analyzed for the noise model and seasonal motions in Taiwan. The noise parameters obtained are also used to evaluate the reliability of GPS velocity uncertainties. GPS data are processed by GAMIT/GLOBK to obtain the position time series. To obtain the seasonal properties in the CGPS time series, we modeled each GPS position time series to derive the secular velocity, seasonal variations in annual and semi-annual periods, offsets due to the antenna changing and co-seismic deformations using the weighted least square method. Uncertainties of the residual position time series after removing the modeling motions for each CGPS station are evaluated by the weighted root mean square (WRMS). The average WRMS of position time series for all CGPS stations are 1.8-2.5 mm and 3.9-7.7 mm in the horizontal and vertical components, respectively. GPS daily position time series are considered to be the signal pattern of the white plus flicker noise. The overall seasonal amplitudes for all the GPS stations are 1.8-3.3 mm in horizontal and 3.2-8.8 mm in the vertical component. Areas of strongest annual amplitudes in both horizontal and vertical components are concentrated in the west and southwest coastal plain in Taiwan which suffers severe ground subsidence from water over-pumping. The motions shown here appear to be elastic and are most likely induced by the effective stress in the regional aquifer changing between expansion and contraction. Stations located just east of the Longitudinal Valley in eastern Taiwan show high correlation between the horizontal seasonal motions and rainfall and groundwater levels. This may be resulted from the periodic contraction and extension motions of the Longitudinal Valley fault due to variations in hydrological loadings. Uncertainty of CGPS velocities estimated by the noise patterns of the Power Law noise series indicated that the uncertainty are 5-12 times larger than those obtained by the noise setting of the white noise pattern.
Rau, Ruey-Juin; Hung, Huang-Kai
Taiwan Earthquake Damage Index Sin Mei Nga* and Masataka Andob a* Department of Geology, Chinese Culture University, No. 55, Hwa-Kang Road, Yang-Ming-Shan, Taipei 11114, Taiwan b Institute of Earth Sciences, Academia Sinica, 128, Sec2, Academia Road, Nangang, Taipei 11529, Taiwan * Corresponding author. Tel.: +886 (02) 28 61 05 11 ext.26133 fax: +886 (02) 28 61 49 59 E-mail: email@example.com or email@example.com
NASA Astrophysics Data System (ADS)
Taking advantage of a previous study and twelve-year, free-field strong motion data in Taiwan, a preliminary, five-level earthquake damage index is newly proposed: I-No (no damage), II-Very Light, III-Light, IV-Moderate, and V-Heavy. For index I, PGA and PGV are, respectively, <62.5 gal and <11 cm/s. Likewise, for index II, PGA is ?62.5 and ?187.5 gal; but, PGV is ?11 and ?35 cm/s. Similarly, PGA is ?187.5 and ?325 gal; but, PGV is ?35 and ?55 cm/s for index III. The corresponding PGA and PGV, for index IV, are ?325 and ?450 gal and ?55 and ?75 cm/s. Finally, for index V, PGA and PGV are respectively >450 gal and >75 cm/s. Ten damaging seismic events in the past twelve years are redefined using this new earthquake damage index, with the devastating Chi-Chi earthquake and one non-damaging event as reference earthquakes. This newly proposed index depicts seismic hazard of these earthquakes with higher accuracy when compared to the existing intensity scale in Taiwan region. For further analysis, Japan earthquakes are also plotted as references.
Ng, S.
Taiwan's second remote sensing satellite
FORMOSAT-2 is Taiwan's first remote sensing satellite (RSS). It was launched on 20 May 2004 with five-year mission life and a very unique mission orbit at 891km altitude. This orbit gives FORMOSAT-2 the daily revisit feature and the capability of imaging the Arctic and Antarctic regions due to the high enough altitude. For more than three years, FORMOSAT-2 has performed
Jeng-Shing Chern; Jer Ling; Shui-Lin Weng
Solar water heater has been commercialized during the last two decades in Taiwan. The government initiated the incentive programs during 1986�1991 and 2000�2004. This created an economic incentive for the end-users. The total area of solar collectors installed was more than one million square meters. The data also show that most of the solar water heaters are mainly used by
K. Chang; T. Lee; K. Chung
Genotoxic Klebsiella pneumoniae in Taiwan
Background Colibactin is a nonribosomal peptide-polyketide synthesized by multi-enzyme complexes encoded by the pks gene cluster. Colibactin-producing Escherichia coli have been demonstrated to induce host DNA damage and promote colorectal cancer (CRC) development. In Taiwan, the occurrence of pyogenic liver abscess (PLA) has been suggested to correlate with an increasing risk of CRC, and Klebsiella pneumoniae is the predominant PLA pathogen in Taiwan Methodology/Principal Findings At the asn tRNA loci of the newly sequenced K. pneumoniae 1084 genome, we identified a 208-kb genomic island, KPHPI208, of which a module identical to the E. coli pks colibactin gene cluster was recognized. KPHPI208 consists of eight modules, including the colibactin module and the modules predicted to be involved in integration, conjugation, yersiniabactin production, microcin production, and unknown functions. Transient infection of BALB/c normal liver cells with K. pneumoniae 1084 increased the phosphorylation of histone H2AX, indicating the induction of host DNA damage. Colibactin was required for the genotoxicity of K. pneumoniae 1084, as it was diminished by deletion of clbA gene and restored to the wild type level by trans-complementation with a clbA coding plasmid. Besides, BALB/c mice infected with K. pneumoniae 1084 exhibited enhanced DNA damage in the liver parenchymal cells when compared to the isogenic clbA deletion mutant. By PCR detection, the prevalence of pks-positive K. pneumoniae in Taiwan is 25.6%, which is higher than that reported in Europe (3.5%), and is significantly correlated with K1 type, which predominantly accounted for PLA in Taiwan. Conclusions Our knowledge regarding how bacteria contribute to carcinogenesis has just begun. The identification of genotoxic K. pneumoniae and its genetic components will facilitate future studies to elucidate the molecular basis underlying the link between K. pneumoniae, PLA, and CRC.
Lai, Yi-Chyi; Lin, Ann-Chi; Chiang, Ming-Ko; Dai, Yu-Han; Hsu, Chih-Chieh; Lu, Min-Chi; Liau, Chun-Yi; Chen, Ying-Tsong
Occupational neurotoxic diseases in taiwan.
Occupational neurotoxic diseases have become increasingly common in Taiwan due to industrialization. Over the past 40 years, Taiwan has transformed from an agricultural society to an industrial society. The most common neurotoxic diseases also changed from organophosphate poisoning to heavy metal intoxication, and then to organic solvent and semiconductor agent poisoning. The nervous system is particularly vulnerable to toxic agents because of its high metabolic rate. Neurological manifestations may be transient or permanent, and may range from cognitive dysfunction, cerebellar ataxia, Parkinsonism, sensorimotor neuropathy and autonomic dysfunction to neuromuscular junction disorders. This study attempts to provide a review of the major outbreaks of occupational neurotoxins from 1968 to 2012. A total of 16 occupational neurotoxins, including organophosphates, toxic gases, heavy metals, organic solvents, and other toxic chemicals, were reviewed. Peer-reviewed articles related to the electrophysiology, neuroimaging, treatment and long-term follow up of these neurotoxic diseases were also obtained. The heavy metals involved consisted of lead, manganese, organic tin, mercury, arsenic, and thallium. The organic solvents included n-hexane, toluene, mixed solvents and carbon disulfide. Toxic gases such as carbon monoxide, and hydrogen sulfide were also included, along with toxic chemicals including polychlorinated biphenyls, tetramethylammonium hydroxide, organophosphates, and dimethylamine borane. In addition we attempted to correlate these events to the timeline of industrial development in Taiwan. By researching this topic, the hope is that it may help other developing countries to improve industrial hygiene and promote occupational safety and health care during the process of industrialization. PMID:23251841
Liu, Chi-Hung; Huang, Chu-Yun; Huang, Chin-Chang
NSDL National Science Digital Library
Students learn why and how motion occurs and what governs changes in motion, as described by Newton's three laws of motion. They gain hands-on experience with the concepts of forces, changes in motion, and action and reaction. In an associated literacy activity, students design a behavioral survey and learn basic protocol for primary research, survey design and report writing.
Integrated Teaching And Learning Program
Active back thrust in the eastern Taiwan suture revealed by the 2013 Rueisuei earthquake: Evidence for a doubly vergent orogenic wedge?
NASA Astrophysics Data System (ADS)
exhumation of 3-10 mm/yr of the Taiwan metamorphic range is often explained as the unroofing of the retrowedge of a doubly vergent mountain belt. Yet, to date, the Central Range fault forming the boundary of the retrowedge has displayed no definitive evidence for recent seismic activity and no unambiguous geomorphic expression over much of the fault. The 2013 M6.4 Rueisuei reverse-faulting earthquake nucleated at the eastern boundary of the retrowedge and appears to illuminate the west dipping Central Range fault. We estimate the fault geometry and coseismic slip distribution using a uniform stress drop slip inversion and surface displacements derived from GPS and strong-motion data. We identify a ~42� dipping blind reverse fault, consistent with the previously proposed buried Central Range fault beneath the highly active Longitudinal Valley fault. This earthquake may be the first indication that rapid exhumation and uplift occur along a distinct fault structure bounding the eastern margin of the Taiwan retrowedge.
Chuang, Ray Y.; Johnson, Kaj M.; Kuo, Yu-Ting; Wu, Yih-Min; Chang, Chien-Hsin; Kuo, Long-Chen
Spatial distribution of non volcanic tremors offshore eastern Taiwan
NASA Astrophysics Data System (ADS)
Non-volcanic tremor (NVT), originally identified in the subduction zone of the southwest Japan, have been well studied in the circum-Pacific subduction zones and the transform plate boundary in California. Most studies related NVT to the release of fluids, while some others associated them with slow-slip events, and can be triggered instantaneously by the surface waves of teleseismic events. Taiwan is located at a complex intersection of the Philippines Sea Plate and the Eurasian Plate. East of Taiwan, the Philippine Sea plate subducts northward beneath the Ryukyu arc. The major part of the island results from the strong convergence between the two plates and the convergent boundary is along the Longitudinal Valley. Moreover, an active strike-slip fault along the Taitung Canyon was reported in the offshore eastern Taiwan. In such complicate tectonic environments, NVT behavior could probably bring us more information about the interaction of all the geological components in the area. In this study, we analyze the seismic signals recorded by the Ocean bottom Seismometer (OBS) deployed offshore eastern Taiwan in September 2009. TAMS (Tremor Active Monitor System) software was used to detect the presence of NVT. 200 tremor-like signals were obtained from the 3 weeks recording period. We use the SSA (Source-Scanning Algorithm) to map the possible distribution of the tremor. In total, 180 tremors were located around the eastern offshore Taiwan. The tremors are mainly distributed in two source areas: one is along the Taitung Canyon, and the other is sub-parallel to the Ryukyu Trench, probably along the plate interface. Many tremors are located at depth shallower than 5 km, which suggests a possible existence of a weak basal detachment along the sea bottom. Other tremors with larger depth may be related to the dehydration of the subducting sea plate as suggested by the former studies. Limited by the short recording period of the OBS experiment, we could not obtain any possible repeating interval and the spatial migration about the tremor occurrence. However, the presence of NVT offshore eastern Taiwan shown in our study still brings us valuable understanding about the undergoing tectonic processes in the marine area.
Xie, X. S.; Lin, J. Y.; Hsu, S. K.; Lee, C. H.; Liang, C. W.
We will give here an overview of our theory of the strong interactions, Quantum Chromo Dynamics (QCD) and its properties. We will also briefly review the history of the study of the strong interactions, and the discoveries that ultimately led to the formulation of QCD. The strong force is one of the four known fundamental forces in nature, the others being the electromagnetic, the weak and the gravitational force. The strong force, usually referred to by scientists as the 'strong interaction', is relevant at the subatomic level, where it is responsible for the binding of protons and neutrons to atomic nuclei. To do this, it must overcome the electric repulsion between the protons in an atomic nucleus and be the most powerful force over distances of a few fm (1fm=1 femtometer=1 fermi=10{sup -15}m), the typical size of a nucleus. This property gave the strong force its name.
Karsch, F.; Vogelsang, V.
Analyzing Strain to Create a Regional Deformation Model of Northern Taiwan
NASA Astrophysics Data System (ADS)
A Global Positioning System (GPS) network is used to calculate the strain and rotations at the intersection of an arc-continent collision and retreating trench in northern Taiwan. The island of Taiwan forms as Eurasia collides obliquely with the Philippine Sea plate (PSP), resulting in substantial along-strike extension throughout the island. In northern Taiwan, the PSP is also subducting towards the northwest beneath Eurasia and the associated Ryukyu trench is rolling back, forming the Okinawa Trough. GPS velocities were collected over a ten-year period (1995-2005) from 125 stations (Rau et al., 2008) and were inverted to calculate the 2D velocity gradient tensors (Allmendinger, Cardozo and Fisher, 2012). In northwest Taiwan, although the GPS velocities relative to the Penghu Island are low, volumetric strains are negative and generally show N-S shortening. Areas of E-W shortening and extension also occur, however. The GPS data suggests a heterogeneous deformation field consistent with the occurrence of thrust (e.g., Hukou fault), strike slip, and oblique slip normal faults (e.g., Nankan and Schanciao) in northwest Taiwan. In northeast Taiwan, GPS velocities show an increase in magnitude from north to south as well as a change from NE trending velocities to SE trending velocities. Volumetric strains are generally positive, indicating extension, which is consistent with spreading in the Okinawa Trough as it propagates into the Ilan Plain. Spreading in the Okinawa Trough and rotation from NE to SE velocities reflect rollback of the Ryukyu Trench. Therefore, northern Taiwan exhibits N-S shortening in the west and rotation and extrusion in the east. This complex deformation pattern is similar to larger continental collision areas such as the extrusion and rotation of China associated with the northward motion of India and the Mediterranean-Middle Eastern extrusion and rotation associated with the northward motion of Arabia. Allmendinger, R.W., Cardozo, N., Fisher, D.M. (2012), Structural Geology Algorithms: Vectors and Tensors, Cambridge University Press, New York, N.Y. Cardozo, N., and Allmendinger, R. W. (2009), SSPX: A program to compute strain from displacement/velocity data, Computers & Geosciences, 35,1343-1357. Rau, R.-J., Ching, K.-E., Hu, J.-C., and Lee, J.-C. (2008), Crustal deformation and block kinematics in transition from collision to subduction: Global positioning system measurements in northern Taiwan, 1995-2005, J. Geophys. Res., 113, B09404, doi: 10.1029/2007JB005414.
VanderLeest, R. A.; Byrne, T. B.; Rau, R.
Seismogenic Structures in Hualien Region, eastern Taiwan
NASA Astrophysics Data System (ADS)
Due to extremely high seismicity and abundant tectonic-influenced geomorphic features, eastern Taiwan has long been known as a tectonically active region. The geological model of an on-going arc-continent collision was successfully proposed to explain the arrangement of the tectonic entities and their interaction. The convergent situation between Eurasia plate and Philippine Sea plate is believed still being existing because of no geomorphic evidence directly related to significant subsidence of the backbone mountain range. However, in the north of the Coastal Range, the Philippine Sea plate is moving northerly downward by the subduction mechanism. Accordingly the fault systems on-land and offshore should be significantly different. With an attempt to answer the puzzle mentioned above we therefore analyze the seismogenic structures in northern part of eastern Taiwan. We adopt the double difference (hypoDD) method to relocate earthquakes, apply the GOCAD (Geologic Computer Aided Design) to visually image the 3D subsurface structures, and determine the rupture plane by the Finite Dimension Source Model (FDSM) from first motion focal mechanisms. Selected earthquakes are (1) located within region between 121.2 �122� E and 23.5 �24.5� N; (2) M{ L }?3; (3) and showing clearly P or S arrived time at least 6 recorded stations. Additionally, we determine the M { L } ?4 focal mechanisms by using the first P wave polarities to examine the reliability of rupture planes determined above. A few of seismogenic structures are clearly identified in this study. Looking at the E-W profile, a major reverse fault dipping 60� to the east is found in depth of 20-40 km beneath the Coastal Range, which is probably the subsurface image of the plate boundary. On the other hand, within the Central Range several N-S oriented high-angle normal faults are found near the surface in the western part of the study area. The second one from the west reflects the subsurface extension of Lishan fault. In the eastern margin of the Central Range seismic clusters in depth of 10-20 km show high-angle reverse faults. Such a situation of compression down beneath but extension above may suggest a flower structure of the back-bone range. To the Hualien coast and offshore area no more mountains exist but we still found a west-dipping thrust in shallow depth, indicating the existence of the shortening. Further north, a complex seismic cluster is dominated by strike-slip and tensional earthquakes, but no fault plane can be recognized by spatial distribution.
Kuochen, H.; Wu, Y.; Chen, Y.; Chen, R.; Kuo, Y.
Scrub Typhus in Eastern Taiwan, 1970.
National Technical Information Service (NTIS)
An outbreak of scrub typhus occurred in Chinese Army personnel in the eastern part of Taiwan during 1970. This is the first outbreak of the disease documented on the main island of Taiwan since 1932. Of 21 hospitalized patients examined during the convale...
J. L. Gale G. S. Irving H. C. Wang J. C. Lien W. F. Chen
Although academic research institutions have become a major player in protecting, transferring, and commercializing their knowledge base, little research has examined in enterprising research results from the angle of academic entrepreneurs. This paper examined the factors fostering academic entrepreneurship from institutional, organizational, and individual aspects, especially in Taiwan. Based on the Patent Database of the National Science Council, Taiwan, 474
Nonextensive analysis of crustal seismicity in Taiwan
Using the Taiwan Central Weather Bureau earthquake catalogue, the crustal seismicity of Taiwan was analyzed by means of a nonextensive approach. The time span of the analyzed catalogue is from 1 January 1990 to 30 November 2007, and only earthquakes with magnitude M>=2.0 were considered. Our findings reveal that the nonextensive statistics furnishes a very good prediction of the cumulative
L. Telesca; C.-C. Chen
Helmet use and motorcycle fatalities in Taiwan
Motorcycle deaths accounted for more than half of total traffic fatalities in Taiwan in 2002. This study uses the police-reported crash data from Taiwan between 1999 and 2001 to estimate the effectiveness of helmets, simultaneously taking into account of sample selection bias. Sample selection arises because helmet usage will affect the probability of death or injury, which in turn influences
Shao-Hsun Keng
The development of Taiwan's integrated circuit industry
The development of Taiwan's integrated circuit (IC) industry is discussed in four sections covering the history of industry. The performance of the industry, the trends and development activities, and the future challenges. The latest data describing the industry are provided by Taiwan ERSO\\/ITRI ITIS project. The data cover the operations, marketing and technology indices, industry development goals, and investment trends
Michael M. K. Lin; Charles V. Trappey
Mountain building in Taiwan: A thermokinematic model
The Taiwan mountain belt is classically viewed as a case example of a critical wedge growing essentially by frontal accretion and therefore submitted to distributed shortening. However, a number of observations call for a significant contribution of underplating to the growth of the orogenic wedge. We propose here a new thermokinematic model of the Taiwan mountain belt reconciling existing kinematic,
Martine Simoes; Jean Philippe Avouac; Olivier Beyssac; Bruno Goff�; Kenneth A. Farley; Yue-Gau Chen
Ethnic Inequalities and Educational Attainment in Taiwan
ERIC Educational Resources Information Center
In this article, the authors examine educational stratification in Taiwan against the background of an ethnically based political economy. They investigate how educational attainment is related to ethnicity and other background factors, such as parental class and education, and if these relationships changed over time as Taiwan became a more�
Jao, Jui-Chang; McKeever, Matthew
Dust Activity during Winter Time in East Asia and Snowfall Obervations and Simulations in Taiwan
NASA Astrophysics Data System (ADS)
Taiwan has relatively frequent snowfall in mountain during winter among regions of the same latitude. The phenomenon is contributed by Taiwan's unique topography - high and steep mountains, and geographical location - sitting on the route the continental polar air mass travels from its birthplace to the ocean, contribute to this phenomenon. Snow occurence, in addition to the freezing-point temperature, when two requirements are met: sufficient vapor and the condensation nuclei in the air. This study pursues the causes of the snowfall activity in Taiwan, the relations between the East Asian dust aerosol and the snowfall activity in Taiwan, and the impacts the climate changes have on the snowfall activity in Taiwan. In this study, Yushan snowfall activity from 1995~2011 and related atmosphere circulations were examined using SYNOP data, NCEP/DOE reanalysis atmospheric data, the observations of the Central Weather Bureau's Yushan Weather Station and the Taiwan Air Quality Monitoring Network of the Environment Protect Administration, Executive Yuan. To provide a quantitative measure of snowfall events and dust activity, a snowfall activity index (SAI) and the DAI Index by Yu et al. (2010) were defined. The time series of yearly SAI and DAI show that East Asian dust storm activity and Taiwan snowfall marked interannual variations during 1995 ~ 2011. For active years such as 2008, 2010, and 2011, SAI was hundreds of times larger than that for inactive years such as 1996, 1999 and 2003; and DAI in active years such as 2001 and 2002 was several tens of times larger than that in inactive years such as 1997 and 2003. In active years when the EAT (East Asian Trough) was shifted eastward, the strength of WPH (West Pacific High) increased in the south and an anticyclone thus occurred. This anticyclone introduced anomalous southwesterly flows along the southeastern coast of mainland China and over Taiwan, resulting in a wetter-than-normal atmosphere in support of snowfall. Oppositely, for inactive years, drier-than-normal atmosphere appeared and consequently sluggish snowfall seasons followed. A SVD (singular value decomposition) analysis of the Asian synoptic circulation indicated that the connection between the pressure dipoles and the position of EAT is strong in 1998, 1999, 2001, 2002, 2003, 2010, and 2011. It significantly affects both of the snowfall and dust activities. In summary, snowfall active years usually occurred when the East Asian dust storm was inactive. Nevertheless, the snowfall activity increased in Taiwan if there was dust event and the dust aerosol successfully transported to Taiwan. This finding is also demonstrated in the model simulation of this study.
Tsai, L.
Internationalization or Commodification? A Case Study of Internationalization Practices in Taiwan's Higher Education
ERIC Educational Resources Information Center
This article examines how commodification and consumerism have sharpened the discourse of internationalization in Taiwan's higher education. Given the strong sense of crisis in the less prestigious universities, this article argues that internationalization is only a means to survive instead of a pursuit of excellence to these universities. This�
Chen, Dorothy I-ru; Lo, William Yat Wai
A model for the termination of the Ryukyu subduction zone against Taiwan: A junction of collision, subduction/separation, and subduction boundaries
The NW moving Philippine Sea plate (PSP) collides with the Eurasian plate (EUP) in the vicinity of Taiwan, and at the same time, it subducts toward the north along SW Ryukyu. The Ryukyu subduction zone terminates against eastern Taiwan. While the Ryukyu Trench is a linear bathym??trie low about 100 km east of Taiwan, closer to Taiwan, it cannot be clearly identified bathymetrically owing to the deformation related to the collision, making the location of the intersection of the Ryukyu with Taiwan difficult to decipher. We propose a model for this complex of boundaries on the basis of seismicity and 3-D velocity structures. In this model the intersection is placed at the latitude of about 23.7??N, placing the northern part of the Coastal Range on EUP. As PSP gets deeper along the subduction zone it collides with EUP on the Taiwan side only where they are in direct contact. Thus, the Eurasian plate on the Taiwan side is being pushed and compressed by the NW moving Philippine Sea plate, at increasing depth toward the north. Offshore of northeastern Taiwan the wedge-shaped EUP on top of the Ryukyu subducting plate is connected to the EUP on the Ryukyu side and coupled to the NW moving PSP by friction at the plate interface. The two sides of the EUP above the western end of the subduction zone are not subjected to the same forces, and a difference in motions can be expected. The deformation of Taiwan as revealed by continuous GPS measurements, geodetic movement along the east coast of Taiwan, and the formation of the Hoping Basin can be understood in terms of the proposed model. Copyright 2009 by the American Geophysical Union.
Wu, F. T.; Liang, W. -T.; Lee, J. -C.; Benz, H.; Villasenor, A.
Orientation-Independent Measures of Ground Motion
The geometric mean of the response spectra for two orthogonal hori- zontal components of motion, commonly used as the response variable in predictions of strong ground motion, depends on the orientation of the sensors as installed in the field. This means that the measure of ground-motion intensity could differ for the same actual ground motion. This dependence on sensor orientation
David M. Boore; Jennie Watson-Lamprey; Norman A. Abrahamson
We describe a simple technique for editing captured or keyframed animation based on warping of the motion parameter curves. The animator interactively defines a set of keyframe-like constraints which are used to derive a smooth deformation that preserves the fine structure of the original motion. Motion clips are combined by overlapping and blending of the parameter curves. We show that
Andrew P. Witkin; Zoran Popovic
Three-Dimensional Tectonic Model of Taiwan
NASA Astrophysics Data System (ADS)
We built a three-dimensional model of the interactions of the Eurasian plate (EUP) the Philippine Sea plate (PSP) and the collisional orogen, in and around Taiwan. The model is based on the results of comprehensive, milt-prong TAIGER experiments on land and at sea as well as other existing data. The clockwise rotating PSP moves NWW at ~8 cm/year relative to the Taiwan Strait. Under northern Taiwan the northward subducting PSP terminates near the edge of eastern Taiwan and collides with EUP at in increasing depth toward the north. Mountain building due to collision of EUP and PSP tapers off where the PSP goes below about 60 km. The PSP in the asthenosphere continues to advance NWW-ward. In central Taiwan PSP and EUP collide fully, lithosphere against lithosphere in the upper 60 km or so, leading to significant thickening of the crust to about 55 km on the Central Range side and about 35 km on the Coastal Range/Arc side. In between these "roots" a high velocity rise is found. Although a clear, steep dipping high velocity zone under Central Taiwan is detected, it is found not to be associated with seismicity. In southern Taiwan, mountains form over well-defined, seismically active subduction zone. The upper mantle high velocity anomaly appears to be continues with that under central Taiwan, but here an inclined seismic zone is found. In this area the Luzon Arc has not yet encountered the continental shelf - thus arc-continental collision has not yet occurred. The orogeny here may involve inversion of the subducted South China Sea lithosphere, rifted Eurasian continent, and/or escape of continental material from central Taiwan. GPS and Leveling data reflect well the 3-D plate collision model.
Wu, Francis; Kuo-Chen, Hao; McIntosh, kirk
The motion of tectonic plates on the earth is characterized in a critical review of U.S. research from the period 1987-1990. Topics addressed include the NUVEL-1 global model of current plate motions, diffuse plate boundaries and the oceanic lithosphere, the relation between plate motions and distributed deformations, accelerations and the steadiness of plate motions, the distribution of current Pacific-North America motion across western North America and its margin, plate reconstructions and their uncertainties, hotspots, and plate dynamics. A comprehensive bibliography is provided. 126 refs.
Gordon, R.G. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))
Study on Seismomagnetism in Taiwan
NASA Astrophysics Data System (ADS)
Since Taiwan is located in high seismicity zone, seismic hazard mitigation is extremely needed. In order to find out any potential precursors before large earthquakes, geomagnetic transfer functions and demodulates are calculated using the geomagnetic data with a sampling interval of one minute at Lunping, Taiwan, Geomagnetic Observatory from 1988 to 2000. These results were correlated to earthquake occurrences. First, traditional transfer functions for the frequencies from 0.1 to 10 cycles/hour are calculated day by day. Monthly means are statistically obtained from these daily values of transfer functions. All the transfer functions show the significant anomalous frequencies at 2, 3, 4, and 6 cycles/hour. Some remarkable changes of transfer function Au, possibly related to the earthquakes which occurred near the Lunping Observatory are found. Second, the Complex demodulation method (CDM) is applied to (1) study the background of the geomagnetic field; (2) set up the method on extraction seismomagnetic signals from the geomagnetic data; and (3) study the characteristics of the seismomagnetic precursory. The results show that the "demodulate" of 1 cycle/day decrease significantly 30 days before high seismicity and retrace to normal value after main shock.
Chen, K.; Chao, K.; Ho, Y.; Chiu, B.; Lin, C.
Turbulent mixing and internal tides in Gaoping (Kaoping) Submarine Canyon, Taiwan
Turbulent overturning on scales greater than 10�m is observed near the bottom and in mid-depth layers within the Gaoping (formerly spelled Kaoping) Submarine Canyon (KPSC) in southern Taiwan. Bursts of strong turbulence coexist with bursts of strong sediment concentrations in mid-depth layers. The turbulence kinetic energy dissipation rate in some turbulence bursts exceeds 10?4�W kg?1, and the eddy diffusivity exceeds
I-Huan Lee; Ren-Chieh Lien; James T. Liu; Wen-ssn Chuang
Some Digenetic Trematodes of Birds from Taiwan.
National Technical Information Service (NTIS)
Thirty-three species of digenetic trematodes of birds are reported from Taiwan. Described are one new genus and eight new species in the following families: Eucotylidae, Brachylaimidae, Echinostomatidae, and Dicrocoeliidae. Previously described species re...
J. H. Fischthal R. E. Kuntz
Sarcocystis sp. in a Taiwan Pig.
National Technical Information Service (NTIS)
During a routine histological examination of swine tissues obtained from a slaughterhouse in Ping Tung, southern Taiwan, Sarcocystis sp. was found encysted in one of 20 pig diaphragms. The cyst appeared to be firmly imbedded in the longitudinal muscles of...
W. D. Kundin B. T. Schaeffer J. H. Cross
Taiwan: Facing the future with nuclear power
The republic of China on Taiwan is located approximately 100 miles off the southeast coast of mainland China, between Japan and the Philippines, and has an area of 13,970 square miles. The island nation has a population exceeding twenty million people, with over five million living in the capital of Taipei, making Taiwan the second most densely populated country in the world. The country also has one of the world`s fastest growing economies, with major industries that include electronics, textiles, food processing, chemicals and plastics. Annual growth of Taiwan`s gross national product (GNP) has averaged more than 7 percent for the past several years, and the small island is now the twelfth largest trading nation in the world, with a GNP exceeding US$200 billion.
Temporal variations of Seismic Velocities after the 2006 Mw6.1 Taitung Earthquake in Taiwan
NASA Astrophysics Data System (ADS)
Impulse response (Green�s function) of a diffusive medium retrieved from cross-correlation of ambient noise at two stations has become widely used in monitoring small temporal changes of subsurface seismic velocities associated with earthquake and volcanic activities. Eastern Taiwan is a seismically very active region resulting from oblique collision between the Eurasian plate under the Philippine Sea plate. A Mw 6.1 shallow earthquake struck eastern Taiwan near Taitung in the southern Longitudinal Valley fault and caused significant coseismic deformation. To detect potential variations in subsurface seismic velocities associated with internal strain change before and after the quake, we construct the Green�s functions from auto-correlation of continuous, one-day long seismic noise on the vertical component in the two months before and after the quake, recorded by seven short-period stations of Central Weather Bureau (CWB) within less than 50 km from the epicenter. Before computing autocorrelation functions (ACF) in frequent domain at each station two months before and after the quake, we employ the time-domain normalization to eliminate earthquake-related signals. A three-order Butterworth band-pass filter between 2 and 8 Hz is then applied to the retrieved ACFs. The spectra of some ACFs within 2-8 Hz show very narrow band-limited resonant peaks which are further removed by a band-stop filter. All the filtered autocorrelation functions with waveform correlation coefficients greater than 0.5 are stacked to obtain reference Green�s function (RGF). We compare the time shift of each daily-long autocorrelation function between 2 and 15-s lapse times with the corresponding RGF. The station TWG, located ~6 km apart from the epicenter on the southern part of the rupture zone yields a clear step-wise time shift after the quake, which corresponds to the increase in seismic velocity by about 1.66% assuming the velocity change in the medium is uniform. The station TTN located on the Taitung city, ~15 km southeast to the epicenter show a slightly decrease by -0.06%. We will further investigate the cause of temporal seismic velocity change by comparing our result with the coseismic displacement measured by GPS and leveling, strong motion records, and volumetric strain perturbations near the rupture zone.
Yu, T.; Hung, S.
A Study of Seismicity and Subsurface Structures by a Temporary Seismic Network in Northwestern Taiwan
NASA Astrophysics Data System (ADS)
The seismicity is low in northwestern Taiwan recently. However, recent studies found special geological characteristics in this area. Besides, many important facilities, and big cities are in this area. Significant shaking intensities were recorded at strong motion stations in the Hsinchu area during the 1999 Chi-Chi earthquake. The disastrous Hsinchu-Taichung earthquake in 1935 occurred in the southern part of this area. Thus, recurrence of potential large earthquakes in this area becomes an important topic. In response, the seismicity and subsurface structures are analyzed in this study. A temporary seismic network consisting of ten seismic stations was deployed in Taoyuan, Hsinchu and Miaoli counties in northwestern Taiwan since January 2001. Each station has one triaxial accelerograph, three external one-component velocity sensors, global positioning system for timing, and a data storage device. Seismic records with absolute timing are critical to obtain accurate earthquake locations. Dense station distribution is necessary to locate earthquakes of lower magnitude from clear seismic signals recorded locally. Based on careful considerations of available instruments and recording sites, the stations were deployed uniformly in the study area. In this study, the arrival time data of the temporary seismic network and CWBSN are combined to locate earthquake. Two dense earthquake clusters in the study area were relocated to compare with several geological cross sections. In order to study the regional stress patterns, numerous focal mechanisms were determined by waveform inversion. By combining the temporary seismic network and CWBSN data, the results of earthquake location show significant convergent in focal depths by adding of near-source arrival time data. Most of the hypocenters are located shallower than 15 km at depth. Relocation of the two dense clusters using the JHD and DD methods was able to remove systematic bias due to one-dimensional velocity model. The events were shifted toward northwest in the horizontal direction and became more tightly clustered at depth from 5 to 10 km. The station corrections of JHD reflected the difference in geology of the northwest and southeast parts of the study area. It is also consistent with distinct topographic features. By comparing the relocated events with several geological cross sections, we found that the seismicity and subsurface structures are related. To determine the focal mechanisms by waveform inversion, we used the acceleration records. The acceleration records of individual stations with three-component sensors are doubly integrated to get displacement waveforms. Then the focal mechanisms are determined by waveform inversion. In total, 88 focal mechanisms were determined with local magnitudes from 1.35 to 3.33. The widespread presences of varying types of focal mechanisms imply that the microearthquakes might be associated with many subfaults.
Lee, C.; Tsai, Y.; Huang, B.
Sudden Sensorineural Hearing Loss: Evidence from Taiwan
Objective:This study uses 5-year population data to determine the incidence rate of sudden sensorineural hearing loss (SSNHL) in Taiwan, taking into consideration the age and gender of patients, as well as seasonal variations. Study Design:A retrospective cross-sectional study. Method: The data used is from the Taiwan National Health Insurance Research Database covering the period from 1998 to 2002. A total
Chuan-Song Wu; Herng-Ching Lin; Pin-Zhir Chao
Tomographic imaging of lithospheric structures under Taiwan
Tomographic images of the crustal and mantle velocity structures under Taiwan are obtained by simultaneous inversion of local earthquake P-wave arrival times for hypocenters and P-wave velocity structures. In northern Taiwan, a high-velocity zone, coinciding with the Wadati-Benioff zone, can readily be identified as the subducted Philippine Sea plate. The imaged zone dips toward the north at an angle of
Ruey-Juin Rau; Francis T. Wu
NSDL National Science Digital Library
This lesson challenges students to apply their knowledge of object motion by animating sequences of hand-rendered pictures that model a set of physical conditions. The challenges include animating the orbital motion of planets and satellites, the effects of gravity on a falling body, and motions of objects in inertial (moving) frames of reference. The lesson was created by a high school physics teacher to help learners build quantitative reasoning skills in preparation for understanding kinematics.
Latham, Ted
Climate and weather characteristics in association with the active fires in northern Southeast Asia and spring air pollution in Taiwan during 2010 7-SEAS/Dongsha Experiment
NASA Astrophysics Data System (ADS)
Climatologically, the East Asian high merges with the westward expansion of the northwestern Pacific subtropical high in March. The local East-West cell/circulation is enhanced by a well-organized convergent center that forms over Indochina at 925 h Pa in March. This allows the emitted air pollutants from the biomass burning to be uplifted to the free troposphere and immediately transported downwind to the east. Using the data collected from the 2010 7-SEAS/Dongsha Experiment, six cases of long-range transport events involving air pollutants during March-April were identified at the Hengchun air quality monitoring station in southern Taiwan. These events were related to active burning phases over Indochina Peninsula. The air pollutants produced by these events were transported to Taiwan after a 2-3 day journey. A composite analysis for these identified six cases showed that the boundary layer of the southwesterly flow confluence coupled with a well-organized convergent center located over a thermal low under clear skies over the Indochina Peninsula may induce a distinct ascending motion to form the upward branch of the transient local East-West cell/circulation during the burning phase. This inferred upward motion together with the strong thermal buoyancy created by the active biomass burnings could carry the air pollutants to the lower free troposphere where they would effectively be conveyed downwind along the westerly flow above 850 h Pa level. The air pollutants were brought down to the surface by downward branch of the transient local East-West cell/circulation, which was induced by the subsidence of a cold surge anticyclone. Using continuous point sources, the six identified cases were simulated with the Hybrid Single-Particle Lagrangian-Integrated Trajectory (HYSPLIT) particle dispersion forward model to confirm our supposition regarding the mechanism for the long-range transport of Southeast Asian biomass burning pollutants that has a significant impact on the surface air quality of the downstream areas, particularly in Taiwan.
Yen, Ming-Cheng; Peng, Chi-Ming; Chen, Tsing-Chang; Chen, Ching-Sen; Lin, Neng-Huei; Tzeng, Ren-Yow; Lee, Yung-An; Lin, Cheng-Chih
Coping with national health insurance: Strategic behaviours of Taiwan�s hospitals
The primary goals of this study are to profile the strategic behaviours of Taiwan�s hospitals under the National Health Insurance programme, identify the related factors for such behaviours, and assess the influences of hospitals� strategic behaviours on their performance. Findings indicate that the most prevalent strategy adopted by hospitals is strategic alliance. The results demonstrate that hospital level is a
Kuo-Cherh Huang; Ning Lu; Yi-Hsin Hsu; Mei-Ling Sheu; Che-Ming Yang; Yi-Hua Chen
Does the Taiwan Warm Current originate in the Taiwan Strait in wintertime?
There is no doubt that the Taiwan Warm Current (TWC) flows through the Taiwan Strait in summer and it reaches the East China Sea (ECS) proper, bringing with it a great deal of nutrients. Here satellite temperature, as well as hydrological, satellite-tracked drifter, and 18O data, are used to show that in winter, warm waters from the South China Sea
Chen-Tung Arthur Chen; David D. Sheu
Opening of the Okinawa basin and collision in Taiwan: a retreating trench model with lateral anchoring
NASA Astrophysics Data System (ADS)
Using a two-dimensional finite element model with an elasto-plastic behavior, we show that the opening of the Okinawa basin behind the Ryukyu trench since about 6 Ma can be explained by a retreating trench model with lateral anchoring due to the collision in Taiwan. We assume that a suction force is applied to the edge of the overriding plate. This force corresponds to the difference between the mean lithospheric pressure in the overriding lithosphere and the normal pressure applied to its edge. It results in an outward motion of the edge of the continental margin (retreating trench) and in the opening of the Okinawa basin. If, on the contrary, no suction force is applied, the collision in Taiwan does not result in any extension in the Okinawa area. On both extremities of the Ryukyu trench, this outward motion is locked by the collision in Taiwan and the buoyant subduction of the Palau-Kyushu ridge. It results in the arcuate shape of the Ryukyu arc. In order to explain the actual amount of extension in the Okinawa basin, it is however necessary to take into account the presence of the Miocene volcanic arc which results in a weakened lithosphere. In our model, this weak zone is simulated by a lower yield condition. Finally, the dissymmetry of the Ryukyu arc and Okinawa basin can be explained by a lateral variation of the suction force related to the variation of the length of the subducting slab, thus of the slab pull force.
Viallon, C.; Huchon, P.; Barrier, E.
NASA Technical Reports Server (NTRS)
Visitors to StenniSphere can feel the motion of a ride to Mars with a ride on StenniSphere's full motion simulator. The simulator is the only attraction at StenniSphere for which there is a charge. Adult rides are $4 and children ride for $3. Group discounts are also available.
Kinematics of Strong Discontinuities
NASA Technical Reports Server (NTRS)
Synthetic Aperture Radar (SAR) provides a detailed view of the Arctic ice cover. When processed with the RADARSAT Geophysical Processor System (RGPS), it provides estimates of sea ice motion and deformation over large regions of the Arctic for extended periods of time. The deformation is dominated by the appearance of linear kinematic features that have been associated with the presence of leads. The RGPS deformation products are based on the assumption that the displacement and velocity are smooth functions of the spatial coordinates. However, if the dominant deformation of multiyear ice results from the opening, closing and shearing of leads, then the displacement and velocity can be discontinuous. This presentation discusses the kinematics associated with strong discontinuities that describe possible jumps in displacement or velocity. Ice motion from SAR data are analyzed using this framework. It is assumed that RGPS cells deform due to the presence of a lead. The lead orientation is calculated to optimally account for the observed deformation. It is shown that almost all observed deformation can be represented by lead opening and shearing. The procedure used to reprocess motion data to account for leads will be described and applied to regions of the Beaufort Sea. The procedure not only provides a new view of ice deformation, it can be used to obtain information about the presence of leads for initialization and/or validation of numerical simulations.
Peterson, K.; Nguyen, G.; Sulsky, D.
75 FR 15726 - Polyvinyl Alcohol From Taiwan; Determination
Federal Register 2010, 2011, 2012, 2013
...injured or threatened with material injury by reason of imports of PVA from Taiwan.\\3\\ Notice of that determination was published...materially injured by reason of imports of subject imports of PVA from Taiwan. Chairman Aranoff and Commissioners Williamson...
New Dryinidae from Sulawesi and Taiwan (Hymenoptera: Chrysidoidea)
The following new species of Dryinidae are described: Anteon heppneri and martiale from Taiwan; Anteon cerberum, flaccum and subdignum; Thaumatodryinus noyesi; Dryinus alboniger and mansus from Sulawesi. The male of Lonchodryinus sinensis Olmi is described from Taiwan.
M. Olmi
Retailing in Taiwan: modernization and the emergence of new formats
Explains that Taiwan�s retailing is predominantly a mix of traditional markets and department stores, an abundance of convenience stores, a group of supermarket and hypermarket chains, many direct marketing companies and a dynamic fast-food industry. Outlines the history of Taiwan�s development as a democratic society in order to provide a framework for describing the modernization process. From the 1600s through
Charles V. Trappey; Meng Kuan Lai
Co-Seismic Indentor-Related Deformation during the Termination of Subduction and its Associated Geophysical Characteristics: An Example from Taiwan
NASA Astrophysics Data System (ADS)
Collision is among the important processes for the growth of continents, and how subduction becomes a collision is still an active research topic. Here we examine the seismogenic structures of southern and central Taiwan where the subduction along the Manila Trench has terminated and given way to an arc-continent collision on land. Based on focal mechanisms and seven finite-fault slip models, co-seismic tectonic extrusion is active in this region in which the basement highs on the in-coming passive margin are acting as indentors, and strongly modify the seismic moment release patterns in the collision zone. At least three magnitude 7 earthquakes have ruptured both north and south of an indentor called the Peikang high in the last hundred years. After examination, the basement highs show little GPS-recorded relative motion with respect to the incoming passive margin; high Bouguer gravity anomaly associated with denser materials of the basement; and low heat flow due to less dewatering and exhumation. With regard to seismogenic structures, faster GPS relative motions, lower Bouguer gravity anomaly, and higher heat flow characterizes the regions surrounding the indentors. Similar processes might be operating in other arc-continent collision zones. For other regions where there are fewer seismic instruments to monitor earthquakes, it might be helpful to combine a geological survey with gravity and other geophysical datasets to help identify such potential seismogenic structures.
Chi, W.
Slow strain variations in Taiwan
NASA Astrophysics Data System (ADS)
Taiwan is located along the boundary between the Philippine Sea plate and the Eurasian plate, one of the most active plate boundaries in the world. The oblique collision between these two plates drives the mountain building and high seismic activity in this area. More than 300 permanent GPS stations are operating, about 1 site per 120 km2. The typical shorting along the plate boundary is about 2~4 mm/yr over 10 km. Over 20 of borehole strainmeters, both Gladwin tensor strainmeters and Sacks-Evertson dilational borehole strainmeter (one and three components), were installed over the island. Slow earthquakes over one or two days of duration were observed several times during 2004 for a network near the plate boundary, and most of them are identified to be triggered by the typhoons. For the largest event on December 3rd, 2004, 3 episodes of slip in this event are identified, and model accordingly, looking for solutions with sources on the fault indicated by the seismicity. All changes are very slow so we use static solutions for deformation due to a buried shear dislocation and generate a time series by successive calculations for a model with slow propagation of the rupture. This very simple model gives a remarkably good fit to the data. Importantly, we can find a reasonable and simple model for a slow earthquake that satisfies the data. Permanent GPS observations over the same area are used to perform the strain time series, and compared with the strainmeter observations. Strainmeter data showed slower strain accumulation than the GPS strain during 2004 while several slow events occurred, and keep similar accumulating rate during 2005-2007. For a strainmeter network (3 stations) near a reservoir in southern-west Taiwan, the orientations of major strain axis of all 3 sites keep stable during 2004 and 2006.5~2007.5, but experienced a rotation of 90 degree during 2005~2006.5. These occurred on all 3 stations, and probably a process of the exchange of major and minor strain axis.
Liu, C.; Hu, J. C.; Chen, C. Y.; Linde, A. T.; Sacks, I. S.
A Perspective of Technology Education in Taiwan, Republic of China
A Brief Review of Taiwan's Educational System The Republic of China was founded in 1911 and moved its seat of gov- ernment from mainland China to Taiwan in 1949. Situated in the far western Pacific, Taiwan covers an area of 36,000 square kilometers (about .38 percent of the area of the USA) and has a population of 20 million. Its
Lung-Sheng Lee
Incidence of eye cancer in Taiwan: an 18-year review
Purpose To describe the incidence and histologic patterns of eye cancers in Chinese in Taiwan.Methods Beginning in 1979, cases of cancer in Taiwan were reported to the Taiwan National Cancer Registry. Information on all Chinese patients diagnosed with eye malignancies under the International Classification of Disease, Ninth Revision, site 190, was retrieved for analysis from the data bank of the
C-Y Cheng; W-M Hsu
The evolution of commercial banking and financial markets in Taiwan
Over the past five decades, Taiwan has achieved rapid economic development. Correspondingly, Taiwan�s financial system has been gradually transformed from a controlled system into a liberalized one, from a state banking system into a private banking one, and from an inward investment system into an outward investment one. In the financial market, the interest rate and foreign exchange rate have
Tzong-shian Yu
Language Shift and Language Accommodation across Family Generations in Taiwan
ERIC Educational Resources Information Center
This study explored language shift and accommodation among bilingual Mandarin and Tai-gi (also called Hokkien, Holo, Tai-gu, Taiwan Min, Taiwanese) families in Taiwan. From the 1940s until the 1980s the Chinese Nationalist Party (KMT) on Taiwan promoted Mandarin Chinese. Recent years have witnessed a shift in policy: since 2001 elementary schools�
Sandel, Todd L.; Chao, Wen-Yu; Liang, Chung-Hui
Large-scale seismic test program at Hualien Taiwan
The large scale seismic test (LSST) program at Hualien, Taiwan, is a follow-on to the soil-structure interaction (SSI) experiments at Lotung, Taiwan. The planned SSI studies are performed at a stiff soil site in Hualien, Taiwan, that historically has had slightly more destructive earthquakes in the past than Lotung. The objectives of the LSST program are as follows: to obtain
H. L. Graves; H. T. Tang; Y. C. Liao
Management of scrap computer recycling in Taiwan.
It is estimated that approximately 300,000 scrap personal computers are generated each year in Taiwan [S.-L. Chang, A Study on the Scrap Computer Treatment Cost, Environment Protection Administration of Taiwan, December 1998 (in Chinese)]. The disposal of such a huge number of scrap computers presents a difficult task for the island due to the scarcity of landfills and incineration facilities available locally. Also, the hazardous materials contained (i.e., phosphor coatings of cathode ray tubes (CRTs), batteries, polychlorinated biphenyl capacitors, mercury-containing parts, liquid crystal display, high-lead content CRT funnel glass, and plastic containing flame-retardant bromine, etc.) in the scrap computers may seriously pollute the environment if they are not properly disposed of. Therefore, the EPA of Taiwan declared scrap personal computers the producer's recycling responsibility as of July 1997. Under this decree, the manufacturers, importers and sellers of personal computers have to properly recover and recycle the scrapped computers which they originally sell. On June 1, 1998, a producer responsibility recycling program for scrap computers was officially implemented in Taiwan. Under this program, consumers can bring their unwanted personal computers to the designated collection points and receive reward money. Currently, only six computer items are mandated to be recycled in this recycling program. They are notebooks, monitors, hard disks, power supplies, printed circuit boards and main frame shells. This article outlines the current scrap computer recycling system in Taiwan. PMID:10751692
Lee, C H; Chang, S L; Wang, K M; Wen, L C
... vestibular sense detects motion while their eyes are fixed on motionless surroundings. Avoid alcohol. Take over the ... better to keep your eyes focused on a fixed object. Drive. Concentrating on the road helps you ...
NSDL National Science Digital Library
Blast a Buick out of a cannon! Learn about projectile motion by firing various objects. Set the angle, initial speed, and mass. Add air resistance. Make a game out of this simulation by trying to hit a target.
Simulations, Phet I.; Dubson, Michael; Adams, Wendy
Geography of suicide in Taiwan: spatial patterning and socioeconomic correlates.
In industrialised Western nations suicide rates tend to be high in inner city areas and socially fragmented neighbourhoods. Few studies have investigated spatial variations in suicide in non-Western settings. We estimated smoothed standardised mortality ratios (1999-2007) for suicide for each of the 358 Taiwanese districts (median population aged 15+: 27,000) and investigated their associations with area characteristics using Bayesian hierarchical models. The geographic distribution of suicide was similar in men and women; young people showed the greatest spatial variation in rates. Rates were highest in East Taiwan, a mostly mountainous rural area. There was no evidence of above average rates in large cities. Spatial patterns of method-specific suicide rates varied markedly, with solids/liquids poisonings showing the greatest geographic variation and hangings the least. Factors most strongly associated with area suicide rates were median household income, population density and lone-parent households. Spatial patterning of suicide in Taiwan differed from that observed in Western nations. Suicide prevention strategies should take into account unique local patterns. PMID:21292534
Chang, Shu-Sen; Sterne, Jonathan A C; Wheeler, Benedict W; Lu, Tsung-Hsueh; Lin, Jin-Jia; Gunnell, David
Taiwan's Capacity-bulding Program on Space Research and Applications
NASA Astrophysics Data System (ADS)
The continuous buildup of the space program in Taiwan over the last decase has led to a series of scientific satellites with important applications in space study remotesensing and meteorology These include the plasma science instrument on the low-Earth orbiting satellite Formosat 1 the high-resoultion camera on Formosat 2 in sunsynchronous orbit and the GPS experiment for atmospheric study on the six microstatellites of the Formosat 3 COSMIC project Further new scientific projects are being planned The space science community in Taiwan therefore stands ready to work closely with COSPAR and its international partners in the promotion of the International Heliospheric Year IHY by providing advanced scientific observations of unique value At the same time the corresponding space research groups have established strong connections to the scientists in Southeast Asia over the last few years by organizing a series of capacity building workshops and international schools covering environmental monitoring land survey climate change atmospheric radar observations and space physics Some of these are sponsored by SARCS Southeast Asia Regional Committee of START and some by the SCOSTEP-CAWSES program In addition a vigorous IHY outreach program connecting high school students to the investigations of space weather and solar physics will be carried out by a consortium led by the Institute of Space Science of National Central University Such scientific infrastructure and experience will be of great value to future capacity-building activity in the serve of
Ip, W. H.; Chen, A. J.; Chu, Y. H.; Lee, L. C.; Liu, C. H.; Lyu, L. H.; Pan, C. J.; Su, S. Y.; Wang, J. T.; Yeh, H. C.
Tide-modulated gas emissions and tremors off SW Taiwan
NASA Astrophysics Data System (ADS)
Escape of methane and carbon dioxide from the seafloor has great impacts not only on the geosphere but also on the biosphere, the hydrosphere and the atmosphere. However, its mechanism is still poorly understood. For that, we have deployed 8 Ocean bottom Seismometers around an active mud volcano off SW Taiwan. We find that the gas emissions from the seabed and the associated tremors off SW Taiwan are strongly correlated with the ocean tides, especially the diurnal and semi-diurnal constitutes. The daily activity of gas emissions and the intensity of tremors are directly proportional to the daily tidal range. Particularly, for each tidal day the gas emissions and long-duration tremors mainly occur at the rising slopes to the higher high tides and at the falling slopes to the lower low tides. It is then suggested that the upward flow of methane beneath the seabed is more active in those periods. Both the individual tremors and long-duration tremors occur as results of the gas expulsions out of the gas-bearing seabed. High-frequency components of the tremors quickly decay and are followed by low-frequency harmonic oscillations. Long-duration tremors can enhance seafloor instability and increase the potential for submarine landslides.
Hsu, S.; Wang, S.; Liao, Y.; Lin, J.; Yang, T. F.; Tsai, C.; Chen, S.
Super Typhoon Halong off Taiwan
NASA Technical Reports Server (NTRS)
On July 14, 2002, Super Typhoon Halong was east of Taiwan (left edge) in the western Pacific Ocean. At the time this image was taken the storm was a Category 4 hurricane, with maximum sustained winds of 115 knots (132 miles per hour), but as recently as July 12, winds were at 135 knots (155 miles per hour). Halong has moved northwards and pounded Okinawa, Japan, with heavy rain and high winds, just days after tropical Storm Chataan hit the country, creating flooding and killing several people. The storm is expected to be a continuing threat on Monday and Tuesday. This image was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite on July 14, 2002. Please note that the high-resolution scene provided here is 500 meters per pixel. For a copy of the scene at the sensor's fullest resolution, visit the MODIS Rapid Response Image Gallery. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC
Using Broadband Seismic Waveforms to Image Seismogenic Structures of Taiwan (Invited)
NASA Astrophysics Data System (ADS)
It is important to study seismogenic structures for regional tectonics and for seismic hazard mitigation purposes. Particularly crucial is to quickly determine the focal mechanisms or even the ruptured fault plane, which require effective procedures to invert high quality seismic waveforms. Recently we have inverted waveforms to study crustal seismogenic structures of Taiwan, some of which show surface expressions. We invert for point source, high-degree moment tensor, and finite fault models to derive earthquake ruptured fault planes and the ruptured extends. The derived fault plans at shallow crust depths are consistent with the results of a large scale seismic reflection survey conducted after the 1999 Chi-Chi earthquake. We also find seismogenic structures in the previous proposed basement at depths, suggesting that active tectonics deformation in Taiwan is not restricted at shallow depths. The rupture extends of a few available large earthquakes are mostly restricted in areas with low heat flows, and do not extend to regions with high heat flows in the hinterlands under the eastern flank of the Central Range. Based on the derived rupture models, we propose that a basement high (Peikang basement high) coming into the convergent zone has strong influences on the seismogenic processes in southern Taiwan. Results from these studies help us locate the ruptured seismogenic planes, and also provide an evolution model of seismic moment release in high-spatial resolution, which can be important for seismic hazard estimates in Taiwan.
Chi, W.