HR: 09:20h
AN: T31G-06    [Abstracts]
TI: Seismicity in Thrust-and-Fold Belt of North Algeria: A Random or Stress Triggering Activity?
AU: Jacques, E
EM: eric.jacques@eost.u-strasbg.fr
AF: EOST-IPGS, 5, rue Ren‚ Descartes, Strasbourg, 67084 France
AU: * Cakir, Z
EM: ziyadin.cakir@eost.u-strasbg.fr
AF: EOST-IPGS, 5, rue Ren‚ Descartes, Strasbourg, 67084 France
AU: Meghraoui, M
EM: mustapha@eost.u-strasbg.fr
AF: EOST-IPGS, 5, rue Ren‚ Descartes, Strasbourg, 67084 France
AU: Ayadi, A
EM: ayadi63@hotmail.com
AF: CRAAG, BP 63 Bouzareah, Algiers, 16340 Algeria
AU: Dorbath, C
EM: catherine.dorbath@eost.u-strasbg.fr
AF: EOST-IPGS, 5, rue Ren‚ Descartes, Strasbourg, 67084 France
AU: King, G C
EM: king@ipgp.jussieu.fr
AF: IPGP, 4, Place Jussieu, Paris, 75252 France
AB: On May 21, 2003, a destructive earthquake (Mw=6.8) occurred near Algiers, the capital city of Algeria. The earthquake is associated with an offshore, NE-SW trending and 45ø SE dipping thrust fault within the actively deforming Tell Atlas thrust-and-fold belt, part of the African-Eurasian plate boundary. In order to study the stress evolution and seismic hazard in the Algiers region, we apply Coulomb friction theory, using maps of surface ruptures and active faults, seismicity catalogue back to 19th century and well located aftershock distribution of the earthquake. Modeling of the historical and instrumental earthquakes in the past 100 years shows that static stress transfer does not seem to play an important role in triggering large earthquakes in this region. In other words, the earthquakes appear to be randomly located. However, it is not known whether this is a common case in a compressional tectonic setting or the time window used is too short to reveal stress interactions between large earthquakes. A longer catalogue may also answer how seismic activity in a thrust-and-fold belt evolves with time. By contrast with strike-slip faults (e.g. North Anatolian or San Andreas faults) that generally form a narrow deformation zone, thrust faults are diffused over a wide area within which fault segmentation is poorly understood. Taking into account the 1716 seismic sequence and fault-related fold segments near the epicentral area, the potential for a large earthquake in Mitidja Basin near Algiers has been increased by the May 2003 event.
DE: 7230 Seismicity and seismotectonics
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting