Frequent failure of the continental slope: The Gela Basin (Sicily Channel)

Evaluating the recurrence of sediment failure on continental margins is important to better understand the evolution of margins and to assess the geologic risk of slope failure and, possibly, tsunami hazard. This paper proposes an integrated morphological and stratigraphic reconstruction of slope failures to evaluate their timing, frequency and responsible mechanisms. Data from seismic stratigraphy, sediment cores and seafloor geomorphology document multiple slide scars as well as buried and exposed mass-transport deposits originated during the Quaternary Period on the continental slope of the Gela Basin, in the Sicily Channel (Central Mediterranean). The very high resolution data provide clues to recognise: 1) successive phases of failure that have impacted on the same location, 2) main geological factors conducive to recurrent sediment failure in the area, including, in particular, specific stratigraphic surfaces acting as glide planes and high pore-pressure gradients likely generated by high sediment accumulation rates atop mass-transport complexes, and 3) a set of failed sediments that have been deposited since the Last Glacial Maximum defining a return interval in the order of 3-4 kyr.