A review of methods used to estimate initial landslide failure surface depths and volumes

Abstract

This paper presents an overview of existing methods developed to characterize initial landslide failure surfaces and compute volumes based on surface information, when it is buried. This paper reviews the simplest models, such as volume estimation based on ellipsoids, and the information that can be obtained from surface displacement and morphology. A simple method to define the volume of a rockslide using the identified discontinuities is also outlined. The sloping local base level (SLBL), which is able to automatically obtain a possible failure surface on the basis of a digital elevation model (DEM), is described. The balanced cross section methods applied to landslides are illustrated and can give the depth of the failure surface. Using predefined assumptions, such as vector displacement parallel to the failure surface, we can obtain an approximation of the failure surface either along translational or circular slides, and this method can be improved by adding a mass balance equation. Recent work has also shown that using an inverse model, a mass balance equation and assumptions about the rheology enables estimation of the failure surface.These methods are illustrated with examples, and they are applied to case studies and compared when the data available makes it possible. The advantages and disadvantages of the methods are discussed. This paper shows that the use high-resolution topography and interpretation of the morphology is underexploited to extract information about failure surfaces geometry.