Urgeles, Roger , Gracia, Eulalia , Lo Iacono, Claudio , Sanchez-Serra, Cristina and Løvholt, Finn (2017) Frequency-Magnitude relationships for Underwater Landslides of the Mediterranean Sea. [Poster] In: AGU Fall Meeting 2017. , 11.12 - 15.12.2017, New Orleans, USA .

Abstract

An updated version of the submarine landslide database of the Mediterranean Sea contains 955 MTDs and 2608 failure scars showing that submarine landslides are ubiquitous features along Mediterranean continental margins. Their distribution reveals that major deltaic wedges display the larger submarine landslides, while seismically active margins are characterized by relatively small failures. In all regions, landslide size distributions display power law scaling for landslides > 1 km3. We find consistent differences on the exponent of the power law depending on the geodynamic setting. Active margins present steep slopes of the frequency-magnitude relationship whereas passive margins tend to display gentler slopes. This pattern likely responds to the common view that tectonically active margins have numerous but small failures, while passive margins have larger but fewer failures. Available age information suggests that failures exceeding 1000 km3 are infrequent and may recur every ~40 kyr. Smaller failures that can still cause significant damage might be relatively frequent, with failures > 1 km3 likely recurring every 40 years. The database highlights that our knowledge of submarine landslide activity with time is limited to a few tens of thousand years. Available data suggest that submarine landslides may preferentially occur during lowstand periods, but no firm conclusion can be made on this respect, as only 149 landslides (out of 955 included in the database) have relatively accurate age determinations. The timing and regional changes in the frequency-magnitude distribution suggest that sedimentation patterns and pore pressure development have had a major role in triggering slope failures and control the sediment flux from mass wasting to the deep basin.

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