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Vortrag, 8. - 12. December
DDC:
550 - Earth sciences
Abstract:
With controlled seismic sources and specifically designed receiver arrays, we imaged a subvertical boundary between two lithological blocks at the Arava Fault (AF) in the Middle East. The AF is the main strike-slip fault of the Dead Sea Transform (DST) between the Dead Sea and the Red Sea. Our imaging (migration) method is based on array beamforming and coherency analysis of P-to-P scattered seismic phases. We use a 1-D background velocity model and the direct P arrival as a reference phase. A spread function describing energy dispersion at localised point scatterers and synthetic calculations for large planar structures provided resolution estimates of the images. We resolve a 7~km long steeply dipping reflector offset roughly 1~km from the surface trace of the AF. The reflector can be imaged down to about 4~km depth. Our results suggest that the AF consists of one dominant fault strand in the uppermost crust. Previous and ongoing studies in this region have shown a strong contrast across the fault: low seismic velocities and electrical resistivities west and high velocities and resistivities east of it. We therefore suggest that the imaged reflector marks the contrast between sedimentary fill in the west and precambrian rocks in the east. This implies that the boundary between the two blocks, i.e. the actual fault location, is about 1~km east of the surface trace of the AF.
