A GIS framework for prediction of basin-wide post-failure geometry of confined subaqueous landslides

Abstract

Stability analysis of submarine and sub-lacustrine slopes requires special attention to the strain-softening nature of clay-rich sediments. Utilizing the often-used infinite slope assumption using the peak strength is inadequate for the task at hand as the well-known limit equilibrium method may provide non-conservative estimate of marine slopes’ stability. In this paper, a GIS based framework is developed to account for a more suitable shear band propagation slope-failure criterion for basin-wide stability calculations. After determining the slab failure prone areas, the framework employs analytical criterion for retrogressive failure above the slab and depth-integrated finite element method for calculating the size of confined slides at the toe. This allows predicting the landslide's post-failure configuration and the overall landslide coverage zone. The framework is first benchmarked to prove its competence and then applied to the well documented Zinnen Slide and the southeastern banks of the Küssnacht Basin, Lake Lucerne, Switzerland. The results of the application show good agreement with the observed basin geomorphology.