Geotechnical properties of marine sediments in the SW Iberia Margin – Implications to marine geohazards.

Submarine mass-failures are recognized worldwide as a potential source of marine geo-hazards. They can compromise the safety and integrity of seafloor and subsurface infrastructures through destroying offshore installations or triggering potential tsunamis. This applies to the SW Iberia Margin, where the occurrence of damaging and tsunamigenic underwater landslides were evidenced in various research works.

This work assesses the geotechnical properties of the marine sediments forming the slopes of the SW Iberia Margin and provides implications to the marine geohazard in the region. Taking advantage of the availability of the cores from previous projects and expeditions (i.e. CONDRIBER, and IODP Expedition-339), we perform conventional Triaxial laboratory tests. These tests allow determining the in-situ shear strength and stress deformation properties, pre-and post-rupture of the undisturbed sediments.

Furthermore, we present, through a landslide case-study in the SW Iberia Margin, a sensitivity analysis of the marine geohazards (sliding mass drag forces and tsunamigenesis) to the geotechnical properties of the marine sediments. We demonstrate that the geotechnical analysis is crucial for an accurate modelling of the submarine mass movements, their impact on offshore installations, and their induced tsunamis.

This work was financed by national funds through FCT—Portuguese Foundation for Science and Technology, I.P., under the framework of the project MAGICLAND – Marine Geo-hazards Induced by Underwater Landslides in the SW Iberian Margin (PTDC/ CTA-GEO/30381/2017).