U.S.-Mexico Collaborative Research: Studies of Seismic Velocity Structure and Attenuation in Northwestern Mexico

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0405425Doser, Diane I. This U.S.-Mexico award will support Dr. Diane Doser of the University of Texas at El Paso in a research collaboration with Dr. Roberto Ortega and Dr. Mario Gonzalez, both of the Centro de Investigacion Cientifica de Educacion Superior de Ensenada (CICESE) in La Paz, Mexico. The researchers intend to use earthquakes occurring within the Gulf of California as seismic sources to study the crustal structure of northwestern Mexico, with emphasis on the Sierra Madre Occidental (SMO), Sonora Basin and Range, Southern Rio Grande rifts, and Central Plateau tectonic provinces. Waveform data recorded by the NARS-Baja broadband network will be used to determine the locations and source parameters of the events. They then will use waveform data from broadband stations within northern Mexico, southern Arizona, southern New Mexico and west Texas for studies of crustal and upper mantle structure. Analysis techniques will include P- and S-wave travel-time analysis, regional waveform modeling of Pnl and surface wave trains, and surface wave dispersion studies. In addition, the researchers will focus on crustal attenuation studies. The research will aid in understanding the tectonic evolution of southwestern North America south of the United States border and the present tectonic activity of the region. Although the area is not as seismically active as parts of southern California or southern/central Mexico, historical earthquakes of magnitude 6.5 to 7.5 have occurred in the region. Thus the attenuation and crustal structure information obtained in this study can be used in future seismic hazard assessment and strong ground motion studies. The study will combine the expertise of the U.S. investigator in seismotectonics and the lithospheric structure of the western United States with the expertise in studies of Baja California seismicity and waveform modeling techniques of her Mexican counterparts.