La historia sísmica durante el Cuaternario Superior de una gran falla direccionalLa Falla de Yusuf (Mar de Alborán)

Laburpena

The identification and the seismic characterization of the active structures in the Alboran Sea is essential to evaluate better the exposure of the South Iberian Peninsula and Maghreb coasts to different natural hazards. The dextral strike-slip Yusuf Fault System (YFS) is a lithospheric boundary between different crustal domains: the East Alboran Basin to the north and the North African Margin to the south. It trends WNW-ESE, is ~150 km-long and has formed a pull-apart basin. The analysis of an ultra-high resolution geophysical dataset acquired with an AUV reveals that this system is a complex structure composed by an array of strike-slip faults. Most of them reach up and offset the seafloor and the Upper Quaternary sedimentary units. The paleoseismic analyses shows that the YFS might have generated at least 8 earthquakes during the past 200 ka. The esti- mated average vertical offset is about 0.64 m, while the vertical slip-rate would be around 0.03 mm/yr. However, this values have to be considered as a minimums since YFS is a strike-slip fault and the lateral slip will be much larger than the vertical one. According to different empirical relationships, the YFS could produce earthquakes over than magnitude Mw 7.0. The results demonstrate that this type of studies are essential to reveal the present-day activity and to characterize the seismic behavior of submarine faults, with crucial implications for seismic (and tsunami) hazard assessment in the surrounding coastal areas.