The nature of small to medium earthquakes along the Eastern Mediterranean passive continental margins, and their possible relationships to landslides and submarine salt-tectonic-related shallow faults

Abstract

AbstractWe analysed here, for the first time, 278 small to medium earthquakes that have occurred since 1985 along a 200 km section of the Levant passive continental margins, offshore Israel. The earthquakes are spatially overlapping with numerous submarine landslides and thin-skinned salt-tectonic-related faults scarps, bisecting the continental slope. Thus, we focus on the genetic relationship between the earthquakes, the faults and the landslides.We found that a subgroup of 55 earthquakes is spatially overlapping with the marine extension of the Carmel Fault and thus might be of tectonic origin. A second subgroup, hosting approximately 130 earthquakes, is spatially overlapping with the longshore salt-tectonic-related submarine faults. However, due to the non-shallow focal depth of most of these earthquakes, salt tectonics was ruled out as their possible seismic origin. Thus, the seismic source for theanalysed earthquakes is yet to be revealed.We further found that the observed medium earthquakes (M > 4) have a calculated reoccurrence time of more than 10 years and they are capable of inducing submarine slope failure within the studied area. Hence, they might play a role in submarine mass-wasting processes along the studied continental slope, and must now be considered in future hazard analysis.