HR: 1340h
AN: S43C-1022    [Abstracts]
TI: Seismogenic structures in the Alboran Sea (Westernmost Mediterranean) characterized by marine geophysical data
AU: * Soto, J I
EM: jsoto@ugr.es
AF: Inst. Andaluz de Ciencias de la Tierra (CSIC-Granada Univ.), Campus Fuentenueva s/n, Granada, 18002 Spain
AU: Gracia, E
EM: egracia@utm.csic.es
AF: Instituto Ciencias del Mar (C.S.I.C.), Paseo Juan de BorbĒn s/n, Barcelona, 08039 Spain
AU: Comas, C
EM: mcomas@ugr.es
AF: Inst. Andaluz de Ciencias de la Tierra (CSIC-Granada Univ.), Campus Fuentenueva s/n, Granada, 18002 Spain
AU: Fernandez-Ibanez, F
EM: fferiba@ugr.es
AF: Inst. Andaluz de Ciencias de la Tierra (CSIC-Granada Univ.), Campus Fuentenueva s/n, Granada, 18002 Spain
AB: In spite of the knowledge on the distribution and character of the upper crustal seismicity in the Alboran Sea (Westernmost Mediterranean) and surrounding Alpine mountain chains (Betics and Rif), and the abundance of geological data on the kinematics and tectonic evolution of recent normal faulting, there is a lack of a satisfactory correlation between the observed structures and the shallow seismicity in the region. This is particularly evident for the seismicity at crustal levels through the northern margin of the Alboran Sea, in where the relationship between the different seismic swarms and the crustal structures is far to be well established. Geological and geophysical surveys carried out recently in the Alboran northern margin (called as the Almeria margin) have been devoted to localize major faulting structures nucleated in the brittle, upper crust, characterizing their incidence in the sea-floor morphology, their connection with onshore seismogenic faults, and their timing, time evolution, and three-dimensional geometry. Using detailed swath bathymetry studies, deep-tow backscatter imaging (TOBI, MAK-1) together with high-resolution, single- and multi-channel seismic profiling, we have studied the upper-crustal structure of the northern margin of the Alboran Sea, in an area close to one of the seismic swarms in the offshore region. In the Almeria margin we have detected and mapped seismogenic fault structures, most of them cutting up to the seabed and with an associated fault escarpment, analyze their 3D geometry, the fault-linkage patterns, their possible kinematics and relationships with the shallow earthquakes. Some of these faults control the current physiography of the margin, determine changes in the orientation and slope of active turbidite channels (like the Almeria canyon), and have important implications for the study of submarine seafloor stability in this seismically active area.
DE: 7230 Seismicity and seismotectonics
DE: 8105 Continental margins and sedimentary basins
DE: 3045 Seafloor morphology and bottom photography
DE: 1208 Crustal movements--intraplate (8110)
DE: 0935 Seismic methods (3025)
SC: Seismology [S]
MN: 2004 AGU Fall Meeting