Sismicidad y Sismotectónica del SW de Iberia

Abstract

The Cape Saint Vincent (SW Iberia) region is of major seismological interest for its tectonic complexity and for the occurrence of the great 1755 Lisbon earthquake that affected the Iberian Peninsula and produced extensive damage generating a large tsunami too. We here examine the mechanism of the three largest earthquakes to have occurred in the last 40 years west of the Cape – 29 July 2003 (Mw=5,3), 12 February 2007 (Mw=6,1), and 17 December 2009 (Mw=5,5). By inversion of the teleseismic body waves we estimated the three earthquakes show NE-SW rupture planes, with horizontal pressure axis compatible with the regional NW-SE horizontal compression produced by the convergence of the Eurasian and African plates. Applied to the generation of the 1755 Lisbon earthquake, this direction of faulting would correspond to a complex rupture along NE-SW trending faults presents in the region.