Submarine landslides and fault scarps along the eastern Mediterranean Israeli continental-slope

Abstract

The present work maps and studies the continental slope off the southeastern Mediterranean Israeli coast. Bathymetric grids with 15–50m/pixel resolution were used to map over four hundred submarine landslides and numerous fault scarps exposed on the sea floor.Landslide scars are found at water depth ranging between 130m and 1000m, where slopes exceed a critical gradient of about 4°–5°. Landslide surface areas range from 0.0024km2 to 91km2, where the observed size distribution has a peak (roll over) showing that the most probable landslide area is 1.6×10−2km2. In general landslides in the north of the studied area are smaller and occur at shallower depth than the southern ones. Landslides show a hierarchical pattern, resulting from sequential, retrograding, slope-failure events and are also observed to interact with a group of faults oriented sub-parallel to the coast. These faults are a result of salt tectonic related extension, their scarps forming elongated step-like morphological features rupturing the surface of the continental slope, as well as the deeper sea floor.The morphology of the landslides as well as their cross cutting relation with the faults scarps, suggest that these landslide are recent, apparently younger than 50,000years. The triggering mechanism is not clear yet, though several conditions which are known to promote slope instability prevail in the studied area: submarine slope gradients are close to the inferred critical slope angle; continuous sedimentation increases the load on the slope; active salt tectonic results in an overall extension and surface rupturing by normal faults; the studied area is merely 100km away from seismogenic zones; and finally, apparent existence of gas close to the surface. Hence, it is suggested that submarine slope failure events in the studied area are also possible in the future.