Relaciones entre fallas y sismicidad en el noroeste peninsular

Abstract

The statistical study of the post-hercynian cartographic faults of the Northwest part of Spain (Galicia) allow to precise the existence of three main fault sets; NE-SW, NW-SE and N-S, which controlled the topograpic features in this area. The seismic epicentres in this region are related mainly with the NE-SW and N-S fault sets, which are, probably, the seismogenetic faults. The orientation of the stresses responsible for the seismic activity been deduced from the analyses of 76 earthquake focal mechanisms. The maximum horizontal compression direction is located NW-SE, then the NE-SW faults move as reverse faults, the NW-SE set as normal faults and the N-S as normal-oblique faults (sinistral).