A Detailed Mapping of Uppermost Mantle Pn Velocities in     Western North America and Other Continental Regions Located Behind Convergent Plate Boundaries
{'Code': '06030204', 'Directorate': {'LongName': 'Directorate For Geosciences'}, 'Division': {'LongName': 'Division Of Earth Sciences'}}
{'SignBlockName': 'Patty Brooking'}
We propose to map in detail uppermost mantle Pn velocities                      beneath western North America and other elevated continental                    regions located behind convergent plate boundaries, such as the                 Tibetan, Turkish-Uranian, and the Altiplano-Puna plateaus on a                  scale comparable to the major tectonic provinces.  This mapping                 will provide critical constraints on the structure and origin                   of continental plateaus.  Such results can be used to answer an                 ongoing debate over the "double" Moho beneath the Great Basin.                  We propose to use the massive digital ISC data in a simple but                  effective way to obtain thousands of Pn velocity determinations,                which will be based on the reports of Pn arrival times from                     about ten thousand events recorded at hundreds of seismic                       stations in western North America.  We plan to use the two-                     station method in which the source is located at epicentral                     distances where Pn is the first arrival and the source is in,                   or very near, the azimuth of the two-station pair.  The station                 pairs are selected to be within definable tectonic provinces.                   A pilot study to map Pn velocity beneath the Colorado plateau                   produced very encouraging results with about a thousand Pn                      velocity determinations.  We plan to extend our efforts to the                  rest of the provinces in western North America, and to other                    elevated continental regions located behind convergent plate                    boundaries.  We also propose to use all available Pn velocities                 and source and station delays, using the procedure of Hearn and                 Clayton.  Because of the large variations in the spatial                        distribution of stations and sources, the resolution of this                    method may vary from one province to another.  The combined                     results of the two-station and tomography methods will provide                  a detailed map of uppermost mantle velocities.
[{'FirstName': 'Thomas', 'LastName': 'Hearn', 'EmailAddress': 'thearn@nmsu.edu', 'StartDate': '08/01/1987', 'EndDate': None, 'RoleCode': 'Co-Principal Investigator'}, {'FirstName': 'Bryan', 'LastName': 'Isacks', 'EmailAddress': 'bli1@cornell.edu', 'StartDate': '08/01/1987', 'EndDate': None, 'RoleCode': 'Co-Principal Investigator'}, {'FirstName': 'Muawia', 'LastName': 'Barazangi', 'EmailAddress': 'barazangi@geology.cornell.edu', 'StartDate': '08/01/1987', 'EndDate': None, 'RoleCode': 'Principal Investigator'}]
{'Name': 'Cornell University', 'CityName': 'Ithaca', 'ZipCode': '148502820', 'PhoneNumber': '6072555014', 'StreetAddress': '373 Pine Tree Road', 'CountryName': 'United States', 'StateName': 'New York', 'StateCode': 'NY'}
{'Code': '1574', 'Text': 'GEOPHYSICS'}
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