GPS studies of active deformation in the Pyrenees

Abstract

The Pyrenees mountain belt, which separates the Iberian Peninsula from the rest of the European continent, is part of the AlpineHimalayan orogenic belt, formed as a result of a collision between the African and Eurasian Plates. Although the instrumental seismicity in the Pyrenees is moderate, in the past centuries a number of destructive earthquakes have occurred, which could indicate continuing tectonic activity of the area. We analyse GPS observations spanning 3.5 yr from 35 continuous stations in the Pyrenees region and find significant on-going extension perpendicular to the range at 2.5 ± 0.5 nstrain yr1, with the possibility of higher strain rates concentrated in the westernmost part of the range. This finding is in agreement with the predominantly normal faulting focal mechanisms of earthquakes that occur in the area and suggests a recurrence time for magnitude 6.5 earthquakes of 22002500 yr