HR: 0800h
AN: G21A-0116    [Abstracts]
TI: InSAR Measurements of Ground Deformation Related to the 2003, May 21 Mw = 6.8 Zemmouri, Algeria Earthquake
AU: * Wicks, C W
EM: cwicks@usgs.gov
AF: USGS, MS 977 345 Middlefield Rd, Menlo Park, CA 94025 United States
AU: Meghraoui, M
EM: mustapha@eost.u-strasbg.fr
AF: Institut de Physique du Globe de Strasbourg, Uni. Strasbourg 5 rue Renes Descartes, Strasbourg, 67084 France
AU: Lu, Z
EM: lu@usgs.gov
AF: USGS/EROS Data Center, 47914 252nd Street, Sioux Falls, SD 57198 United States
AU: Lin, J
EM: jlin@whoi.edu
AF: Woods Hole Oceanographic Institution, MS 22, Woods Hole, MA 02543 United States
AU: Cakir, Z
EM: ziyadin.cakir@eost.u-strasbg.fr
AF: Institut de Physique du Globe de Strasbourg, Uni. Strasbourg 5 rue Renes Descartes, Strasbourg, 67084 France
AU: Stein, R
EM: rstein@usgs.gov
AF: USGS, MS 977 345 Middlefield Rd, Menlo Park, CA 94025 United States
AU: Belabbes, S
EM: samir@eost.u-strasbg.fr
AF: Institut de Physique du Globe de Strasbourg, Uni. Strasbourg 5 rue Renes Descartes, Strasbourg, 67084 France
AU: Maouche, S
AF: Centre de Recherche en Astromie, Astrophysiqaue et Geophysique, BP 63, Bouzareah, Algiers, 16340 Algeria
AB: The Mw=6.8 Zemmouri earthquake was the largest earthquake felt in the region around Algiers since 1716. The quake occurred on a thrust fault within a system of folds and thrusts in northern Africa resulting from convergence between the African and Eurasian plates. Modern seismicity in the Atlas Mountains of northern Africa indicates that this fold and thrust belt is active, although the partitioning of strain within the belt is poorly understood. Because of the high population density in northern Algeria and tragic loss of life resulting from the Zemmouri earthquake, it is important to use all seismological, geodetic, and stress analysis tools available to study this earthquake and analyze its implications for future seismic hazards. We have processed and are analyzing the InSAR data from the Canadian Space Agency RADARSAT-1 satellite. We gained access to the data through the Alaska Satellite Facility with support from NASA and the Office of U.S. Foreign Disaster Assistance. The data reveal the two-patch nature of the rupture associated with the Zemmouri earthquake. This is in general agreement with field work by Meghraoui et al. (GRL, in press) that used shoreline uplift, GPS, and leveling measurements to show that the Zemmouri rupture occurred on two patches, one east and one west of the epicenter. Although InSAR coherence in the area around the epicenter is poor, as much as 0.45 m of InSAR measured uplift can be seen in the area of Boumerdes in the patch west of the epicenter. This is the same area where Meghraoui et al. measured shoreline uplift that was generally between 0.4 and 0.6 m, but as much as ~0.8 m. We are incorporating the disparate data sets and investigating how the addition of InSAR data might offer improvement over models derived from field data alone. We have also calculated patterns of stress transfer caused by the 2003 Zemmouri earthquake. Preliminary results reveal that the Zemmouri quake increased stresses on the thrust fault system in the Mitidja Basin south east of Algiers, especially on the thrust faults immediately southwest of the 2003 rupture zone.
DE: 8110 Continental tectonics--general (0905)
DE: 8164 Stresses--crust and lithosphere
DE: 1208 Crustal movements--intraplate (8110)
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting