HR: 0800h
AN: T51A-03    [Abstracts]
TI: Seismic Structure of the Half-Graben of Santiaguillo, Durango, Mexico
AU: * Gomez-Gonzalez, J M
EM: gomez@geociencias.unam.mx
AF: Centro de Geociencias Universidad Nacional Autonoma de Mexico, Blvd. Villas del Meson s/n Provincia Juriquilla, Queretaro, Qro 76230, Mexico
AU: Nieto-Samaniego, A F
EM: afns@geociencias.unam.mx
AF: Centro de Geociencias Universidad Nacional Autonoma de Mexico, Blvd. Villas del Meson s/n Provincia Juriquilla, Queretaro, Qro 76230, Mexico
AU: Barajas-Gea, I
EM: barajasgea@geociencias.unam.mx
AF: Centro de Geociencias Universidad Nacional Autonoma de Mexico, Blvd. Villas del Meson s/n Provincia Juriquilla, Queretaro, Qro 76230, Mexico
AU: Alaniz-Alvarez, S A
EM: alaniz@geminis.geociencias.unam.mx
AF: Centro de Geociencias Universidad Nacional Autonoma de Mexico, Blvd. Villas del Meson s/n Provincia Juriquilla, Queretaro, Qro 76230, Mexico
AU: Diaz-Baez, I
EM: jarod1881@hotmail.com
AF: Centro de Geociencias Universidad Nacional Autonoma de Mexico, Blvd. Villas del Meson s/n Provincia Juriquilla, Queretaro, Qro 76230, Mexico
AB: The Santiaguillo half-graben is part of the San Luis-Tepehuanes fault system, which is a major structure separating two physiographic provinces, the Mesa Central and the Sierra Madre Occidental. The younger movement of the faults is Quaternary, which is affecting the rocks of the Durango volcanic field. In this work, we study the faults and grabens forming the complex structure of the Santiaguillo half-graben. These structures result from active extensional tectonics since the Oligocene. The contemporary tectonic deformations have been manifested in the last 50 years by a number of earthquakes occurred in the region (1.2 < M < 4.5, epicenter depths < 10 km). The most recent event occurred on July 29, 2003, is a small-sized earthquake M4.5 reported by the Servicio Sismologico Nacional (SSN) that struck the middle of the basin. Some other small-sized earthquakes, microseismicity and swarms occurred around the basin. However, the lack of permanent seismic stations has prevented a recorded history of this activity. We report the preliminary results from the Durango network, which consists of an 8-station passive short-period array deployed around the Laguna de Santiaguillo. This temporal and portable network has been installed for a period of roughly 12 months starting in April 2006, over an area of about 80 km length and 40 km width. The overall aim of our experiment is to understand the driven forces controlling the tectonics of the western side of the Mesa Central in western Mexico. We combine structural observations and recorded seismicity to locate the potential seismogenic structures. Another objective is characterizing some of the crustal properties in the region. Results show a sparsed and scattered seismic activity. We recorded about 50 microearthquakes, half of them were located out side of the array. Bulk of this activity does not coincide with previously reported activity, which implies a more difficult definition of the seismogenic zones.
DE: 7205 Continental crust (1219)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8010 Fractures and faults
DE: 8015 Local crustal structure
DE: 8168 Stresses: general
SC: Tectonophysics [T]
MN: 2007 Joint Assembly