Abstract
The Pyrenees have experienced at least seven earthquakes with magnitude M > 5 in the last 400 years. During the last decades, several seismotectonic, neotectonic and paleoseismological studies have focused on identifying the main active structures of the areas experiencing damaging earthquakes. In spite of these studies, the regional stress regime is still discussed and there is no unequivocal seismotectonic model at the scale of the range. In this paper, we first present a revision of the former works on active faults in the Pyrenees, and then we discuss the main results in terms of their neotectonic setting. We have distinguished five neotectonic regions according to their seismicity, faulting style and morphologic evolution: the westernmost Pyrenees, the North Western Pyrenean zone, the Foreland basins, the Lower Thrust Sheets Domain and the Eastern Pyrenees. This review lead us to differentiate the range into two major domains: the High Chain, where active faults are controlled by vertical maximum stresses, and the Low Chain, where horizontal maximum stresses of variable orientation seem to be dominant. We propose that these different stress domains are related to the isostatic rebound in response to either the difference in crustal thickness and/or the distribution of the Plio-Quaternary erosion.
Highlights
Present-day plate convergence between Africa and Western Europe is mostly accommodated along the structures comprising the Betics-Alboran-Rif and Atlas domains
This paper searches 1) to summarize the potentially seismogenic faults previously identified in the Pyrenees, 2) to distinguish the neotectonic domains in which these structures are active and 3) to propose a geodynamical model explaining the co-existence of the active structures at a Pyrenean scale
It is difficult to identify and characterize the active faults as illustrated by the limited number of conclusive studies dealing with active tectonics
Summary
Present-day plate convergence between Africa and Western Europe is mostly accommodated along the structures comprising the Betics-Alboran-Rif and Atlas domains. In the Pyrenees, the Present-day interplate velocity is certainly small, as attested by GPS measurements performed across the range over 10 years, which show uncertainties greater than the tectonic signal (< 1 mm/yr, Nocquet and Calais, 2004; Asensio et al, 2012) In spite of this slow deformation rate, the Pyrenees exhibit continuous seismic activity and are the second most seismically area of the Iberian Peninsula and the main seismogenic region of continental France, as shown by its instrumental and historical seismicity (Fig. 1; Fig. 2; Souriau and Pauchet, 1998; Souriau et al, 2001; Rigo et al, 2005; Jiménez et al, 1999; Herraiz et al, 2000; Olivera et al, 2006). This paper searches 1) to summarize the potentially seismogenic faults previously identified in the Pyrenees, 2) to distinguish the neotectonic domains in which these structures are active and 3) to propose a geodynamical model explaining the co-existence of the active structures at a Pyrenean scale
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