Seismicity and focal mechanisms in South Spain

Abstract

Abstract Recent improvements in regional seismological networks allow a better definition of the seismicity and the determination of focal mechanisms in south Spain. This region is part of the lithospheric plate boundary between Africa and Eurasia and shows a continuous seismic activity of moderate magnitude ( M h h ≈ 650 km) earthquakes also occurring in the region. Eight fault-plane solutions have been determined that can be related to the tectonics of the area. The solutions for the shallow shocks are compatible with regional stresses with horizontal compressions in NW-SE direction and tensions in E-W direction that produce normal faulting along the N30° to 60°W and N10° to 30°E systems of faults. The mechanisms of the intermediate depth shocks can be explained in terms of a subduction zone from Africa in a NW direction that is under compression.