Simple criteria for Ploughing and Runout in post-failure evolution of submarine landslides

Abstract

This paper extends shear band propagation analysis of slope failures to the investigation of ploughing and runout phenomena in submarine landslides. The ability to predict the two different modes of post-failure landslide evolution is critical for determining the tsunami hazard and type of landslide impact on offshore structures. The proposed analysis is based on the analogy between ploughing and spreading failures. It uses the energy balance approach to develop the criterion for progressive shear band propagation driven by accumulation of sliding material on top of the stable slope. This criterion is then combined with the kinematic passive block mechanism to produce analytical ploughing failure criteria formulated in terms of the critical rise in the seabed level. If the minimum rise of the seabed level at which ploughing can take place is larger than the maximum possible free-standing step in the seabed surface, the first passive failure block will start crumbling over top the stable zone causing the landslide to runout. Application of the derived criteria to the analysis of observed geomorphological features is demonstrated using an example of a paleolandslide complex in the Caspian Sea.