HR: 1330h
AN: S42E-0216    [PDF]
TI: Active Deformation Along the Algerian Margin (MARADJA Cruise): Framework of the May 21, 2003, Mw-6.8 Boumerdes Earthquake
AU: * Deverch\`{e}re, J
EM: jacdev@univ-brest.fr
AF: Universit\'{e} de Bretagne Occidentale, IUEM-UMR6538 Place Nicolas Copernic, Plouzan\'{e}, 29280 France
AU: Yelles, K
AF: CRAAG, Algiers, Alger, 16340 Algeria
AU: Calais, E
EM: ecalais@purdue.edu
AF: Purdue University, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051 United States
AB: The May 21, 2003, Mw=6.8 Boumerdes earthquake (Algeria) ruptured a $\sim$60 km long fault, previously unknown, located a few km off the coast of Algeria, causing major damage and casualties on land. The MARADJA cruise (Suroit R/V, Aug.-Sept. 2003), dedicated to a survey of the Algerian margin in order to determine its present-day tectonic regime and identify potentially active faults, allowed for a detailed study of the Boumerdes earthquake rupture area. From a high-resolution multibeam bathymetry and back-scattering data, 3.5 kHz profiles (Chirp), 6 and 24-channel seismic reflection lines, we produced the first detailed morpho-tectonic map of the central Algerian margin and deep basin. The margin and the proximal part of the deep basin show a series of north-verging reverse faults and folds, probably developping over south-dipping ramps. The northern front of this compressional deformation zone reaches $\sim$20 km into the deep basin, where it interacts with salt-related deformation of the Messinian evaporites, possibly gravity driven in part, widespread in the deep basin. In the area of the May 21, 2003, earthquake, we found active fault scarps delineating a $\sim$60 km long fault zone at the bottom of the continental slope and at midslope, $\sim$17 km offshore and roughly parallel to the coast. The fault consists of at least two major segments striking N65 and N71. It might represent the place of rupture of the Boumerdes earthquake. Its location is consistent with the aftershock distribution and with preliminary dislocation models based on GPS data and uplfit observations onland. The MARADJA Scientific Party: Bouillin J-P., Bracene R., Gaullier V., Kherroubi A., Mercier de Lepinay B., Le Roy P., Pauc H., Savoye B.
DE: 7215 Earthquake parameters
DE: 7223 Seismic hazard assessment and prediction
DE: 7230 Seismicity and seismotectonics
DE: 8010 Fractures and faults
SC: Seismology [S]
MN: 2003 Fall Meeting