Modelling rock avalanches and their relation to permafrost degradation in glacial environments

High runout distances characterize landslides falling on glaciers because of (1) low friction offered by ice to sliding and (2) complex rock-ice interactions that take place during mass motion. Block-fall models (two (2D) and three dimensional (3D)) were tested on the 1936 Felik landslide (Mount Rosa Massif). Geotechnical parameters were assessed through a back-analysis aided by field surveys, aerial photo and historical data analysis. Outcomes are verified for two rock-ice avalanches which ran along the Brenva Glacier (Mount Blanc Massif) in 1920 and 1997. Empirical models show poor precision (75%). 3D numerical models are too complex but 2D ones gave results that pointed out that real runouts exceed predicted ones by 30%, possibly due to fluidization processes. Rock-ice avalanches require attention because they originate in areas likely destined to experience permafrost degradation and glacier retreat. Copyright (C) 2002 John Wiley Sons, Ltd.