HR: 0800h
AN: S31A-08    [Abstracts]
TI: Seismicity in the Gulf of California Region Recorded by the NARS-Baja Array: Preliminary Results
AU: * Castro, R R
EM: raul@cicese.mx
AF: CICESE, Division Ciencias de la Tierra, Departamento de Sismologia, Km 107, carretera Tijuana-Ensenada, Ensenada, BC 22860, Mexico
AU: Mendez, I
EM: nacho@cicese.mx
AF: CICESE, Division Ciencias de la Tierra, Departamento de Sismologia, Km 107, carretera Tijuana-Ensenada, Ensenada, BC 22860, Mexico
AU: Perez-Vertti, A
EM: aperez@cicese.mx
AF: CICESE, Division Ciencias de la Tierra, Departamento de Sismologia, Km 107, carretera Tijuana-Ensenada, Ensenada, BC 22860, Mexico
AU: Mendoza, A
EM: antonio@cicese.mx
AF: CICESE, Division Ciencias de la Tierra, Departamento de Sismologia, Km 107, carretera Tijuana-Ensenada, Ensenada, BC 22860, Mexico
AU: Inzunza, L
EM: inzunza@cicese.mx
AF: CICESE, Division Ciencias de la Tierra, Departamento de Sismologia, Km 107, carretera Tijuana-Ensenada, Ensenada, BC 22860, Mexico
AB: We report the epicentral coordinates of small to moderate size earthquakes recorded by the broadband stations of the Network of Autonomously Recording Seismographs (NARS)-Baja array between April 2002 and August 2006. The NARS-Baja array consists of 19 stations installed in Baja California and Sonora, Mexico. We initially searched for earthquakes reported by the PDE in the Gulf of California region for the period of interest and we found events with magnitudes ranging between 3.2mb and 6.7Ms. Then we relocated those events using P and S wave arrivals recorded by the NARS-Baja array and the RESBAN array (a broadband seismic array with additional stations located in Sinaloa, Sonora and Baja California, Mexico). We found that most of the seismicity is distributed in the NW-SE direction along the axis of the Gulf of California, following a linear trend that steps in the NE direction near the Guaymas and Tepoca basins. We compared the epicentral locations reported in the PDE with the locations obtained using regional arrival times and we found that earthquakes with magnitudes in the range 3.2-5.0mb differ on the average by as much as 43 km. For the magnitude range between 5 and 6.7 the discrepancy is less, differing on the average by about 25 km. To evaluate the energy released by the earthquakes analyzed, we summed the seismic energy released by individual events dividing the region in bins of three degrees wide between latitudes 23ºN and 31ºN. We found that for the time period considered, most of the seismic energy was released in the middle part of the Gulf of California between 27ºN and 29ºN.
DE: 7200 SEISMOLOGY
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Seismology [S]
MN: 2007 Joint Assembly