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Self‐contained local broadband seismogeodetic early warning system: Detection and location

Earthquake and local tsunami early warning is critical to mitigating adverse impacts of large‐magnitude earthquakes. An optimal system must rely on near‐source data to maximize warning time. To this end, we have developed a self‐contained seismogeodetic early warning system employing an optimal combination of high‐frequency information from strong‐motion accelerometers and low‐frequency information from collocated Global Navigation Satellite Systems (GNSS) instruments to estimate real‐time displacements and velocities. Like GNSS, and unlike broadband seismometers, seismogeodetic stations record the full waveform, including static offset, without clipping in the near‐field or saturating for large magnitude earthquakes. However, GNSS alone cannot provide a self‐contained system and requires an external seismic trigger. Seismogeodetic stations detect P wave arrivals with the same sensitivity as strong‐motion accelerometers and thus provide a stand‐alone system. We demonstrate the utility of near‐source seismogeodesy for event detection and location with analysis of the 2010 Mw7.2 El Mayor‐Cucapah, Baja, California and 2014 Mw6.0 Napa, California strike‐slip events, and the 2014 Mw8.2 Iquique, Chile subduction zone earthquake using observatory‐grade accelerometers and GPS data. We present lessons from the 2014 Mw4.0 Piedmont, California and 2016 Mw5.2 Borrego Springs, California earthquakes, recorded by our seismogeodetic system with Micro‐Electro Mechanical System (MEMS) accelerometers and GPS data and reanalyzed retrospectively. We conclude that our self‐contained seismogeodetic system is suitable for early warning for earthquakes of significance (>M5) using either observatory‐grade or MEMS accelerometers. Finally, we discuss the effect of network design on hypocenter location and suggest the deployment of additional seismogeodetic stations for the western U.S.