Slope failure and mass movements in the Sines Contourite Drift (West Portuguese Margin): preliminary results

Abstract

The Sines Contourite Drift, located in the West Portuguese Margin, is affect by slope failure and mass movements. Evidences of the occurrence of such processes are seen in seismic reflection seismic and multibeam bathymetry acquired in this margin during several cruises. An extensive area of the Sines Drift, about approximately 52 km long and 34 km wide, affected by failure and mass movements was discovered during the MOWER cruise in September-October of 2014. The Sines Drift is a plastered drift developed in the footwall of the Pereira de Sousa Fault, a normal inactive fault inherited from the Mesozoic rifting phases. The gravity-driven deposits resulting from its failure (e.g slumps, debris flows) accumulated in the Lebre Basin. Seeing the seismotectonic framework of the WPM earthquake triggering could be considered, but the geotechnical nature and specific physical/sedimentological properties of the contourite deposit need to be taken in account