Submarine landslides and the importance of the initial sediment composition for run-out length and final deposit

Abstract

Much remains to understand the dynamic processes during the flow of submarine landslides. A first relevant problem is to explain the extraordinary mobility of submarine landslides, which has no comparison in subaerial mass movement. Another challenging question is the apparent disparity between submarine landslides that remain compact for hundreds of kilometres and those that disintegrate during the flow, finally evolving into turbidity currents. This problem is linked to a central ongoing debate on the relative importance of turbidity currents versus submarine landslides in reshaping the continental margin. Based on three epitomic case studies and on laboratory experiments with artificial debris flows of various composition, we suggest a possible explanation for the disparity between compact and disintegrating landslides, identifying the clay-to-sand ratio as the key control parameter.