Runout of Submarine Landslide Simulated with Material Point Method

Most of the present knowledge on submarine landslides relies upon back-analysis of post-failure deposits identified using geophysical techniques. In this paper, the runout of slides on rigid bases is explored using the material point method with focus on the geotechnical aspects of the morphologies. In MPM, the sliding material and bases are discretised into a number of Lagrangian particles, and a background Eulerian mesh is employed to update the state of the particles. The morphologies of the slide can be reproduced by tracking the Lagrangian particles in the dynamic processes. A real case history of a submarine slide is back-analyzed with the MPM and also a depth-averaged method. Runout of the slides from steep slopes to moderate bases are reproduced. Then different combinations of soil and basal parameters are assumed to trigger runout mechanisms of elongation, block sliding and spreading. The runout distances predicted by the MPM match well with those from large deformation finite element analysis for the elongation and block sliding patterns. Horst and grabens are shaped in a spreading pattern. However, the current MPM simulations for materials with high sensitivities are relatively mesh sensitive.