Seismic activity in the Ubaye Region (French Alps) : a specific behaviour highlighted by mainshocks and swarm sequences

Description

The Ubaye Region is the most seismically active region in the Western Alps, with earthquakes that were commonly felt by the population and that even damaged local villages and cities. Since the 18th century, this area has been regularly struck by seismic swarms with high number of events, such as in 2003-2004 or 2012-2016 or by mainshock-aftershock sequences with magnitude up to ML 5.3 in 1959. In this poster, we analysed both historical records and instrumental seismicity in the light of geological observations. Some earthquakes could be associated with known faults, even if most of them occurred on blind, unknown faults that reveal a highly-fractured basement. The abnormal level of seismicity, together with its peculiar behaviour, suggests complex driving processes, involving tectonic loading but also fluid pressure.

Abstract

International audience

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