HR: 0800h
AN: S21B-0274    [Abstracts]
TI: A Comparative Aftershock Study for the 2003 Armeria, Colima, Mexico, Earthquake (Mw=7.4)
AU: * Nunez-Cornu, F J
EM: fcornu@pv.udg.mx
AF: Centro de Sismologia y Volcanologia de Occidente, CUC-CUCSH Univ. de Guadalajara, Av. Universidad 203, Puerto Vallarta, Jal 48280 Mexico
AU: Marquez-Ramirez, V H
AF: RESCO, Univ de Colima, 25 de Julio 602, Colima, Col 28045 Mexico
AU: Rutz Lopez, M
EM: marta@iberalp.es
AF: Centro de Sismologia y Volcanologia de Occidente, CUC-CUCSH Univ. de Guadalajara, Av. Universidad 203, Puerto Vallarta, Jal 48280 Mexico
AU: Reyes-Davila, G A
EM: gard@cgic.ucol.mx
AF: RESCO, Univ de Colima, 25 de Julio 602, Colima, Col 28045 Mexico
AU: Suarez-Plascencia, C
EM: csuarez@cencar.udg.mx
AF: Centro de Sismologia y Volcanologia de Occidente, CUC-CUCSH Univ. de Guadalajara, Av. Universidad 203, Puerto Vallarta, Jal 48280 Mexico
AU: Trejo Gomez, E
AF: Centro de Sismologia y Volcanologia de Occidente, CUC-CUCSH Univ. de Guadalajara, Av. Universidad 203, Puerto Vallarta, Jal 48280 Mexico
AB: The seismic sequence of the January 22, 2003 Armeria Earthquake, was recorded by the two permanent seismic networks in the region: the Colima Seismic Network (RESCO) and the Jalisco Seismic Network (RESJAL). Additionally a portable seismic network with seven digital stations with triaxial sensors was deployed from 25 to 31 January. A total of 110 aftershocks were located by RESJAL and RESCO for whole the period, and 272 events were located using data from the portable network. Analysis of the first 72 hours (72 events) shows two groups of events, one the near of the 1995 Earthquake (M = 8.0) epicenter with an almost vertical distribution of events between 2 and 12 km depth. The second group around and north of the mainshock with a distribution dipping about $40\deg$ in an almost EW direction which agrees with focal mechanism for mainshock. These data indicate that the Earthquake was a continental intraplate inverse fault event and do not support the possible rupture of the Colima Gap. The aftershocks recorded by the portable network present a similar epicentral distribution, however most of the events are deeper, between 12 and 30 km. We observe two tendencies one seems distributed between 12 and 22 km along the interphase between Jalisco Block and Rivera Plate assuming a $12\deg$ dipping. The second one between 22 and 30 km depth and dipping about $40\deg$ across (?) the Rivera Plate. We present a comparative analysis of these results including join focal mechanism solutions for both sets of data.
DE: 7223 Seismic hazard assessment and prediction
DE: 8107 Continental neotectonics
DE: 8123 Dynamics, seismotectonics
DE: 7200 SEISMOLOGY
DE: 7205 Continental crust (1242)
SC: Seismology [S]
MN: 2004 AGU Fall Meeting