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Abstract. Rockfalls are common instabilities in alpine areas and can cause significant damage. Since high mountains have been affected by an increasing number of these phenomena in the last years, a possible correlation with permafrost degradation induced by climate change has been hypothesized.To investigate this topic, a monitoring system, made of 5 triaxial geophones and 1 thermometer, was installed in 2007 at the Carrel hut (3829 m a.s.l., Matterhorn, Northwestern Alps), in the frame of the Interreg IIIA Alcotra project n. 196 "Permadataroc".The preliminary data processing relates to the classification of recorded signals, the identification of the significant microseismic events and the analysis of their distribution in time and space. The first results indicated a possible correlation between clusters of events and temperature trend, and a concentration of events in specific sectors of the rock mass.Research is still in progress. The recording of data for a longer period is planned to fully understand seasonal trends and spatial distribution of microseismic activity, and possible relations with permafrost degradation. Nevertheless, the preliminary observations prove that the monitoring system can detect noises generated by rock slope deformation. Once fully developed, this technique could become a helpful tool for early warning and preliminary stability assessments.

In July 1987 a landslide affected the Val Pola (Central Alps, Italy) causing several casualities and severe damage. The main conditioning and triggering factors for the huge debris avalanche are described and possible mechanisms are suggested. Present‐day high‐mountain periglacial conditions (such as rock glaciers) present in the area highlight the probable role played by the presence of mountain permafrost in triggering the slope instability.

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 © 2002 John Wiley & Sons, Ltd.

Sediment gravity flows are very common sedimentary processes in the Alpine region and are often characterized by rapid deposition of large amounts of material. Hazard evaluation in such mountainous areas depends on proper identification of the dominant sedimentary processes, interpreted both from modern and ancient sedimentary facies and their distribution. Three main groups of alluvial fans, characterized by different dominant sedimentary processes, have been distinguished on the basis of lithological characteristics of the catchment area. The dominant catchment lithologies are: 1 massive and/or crudely stratified carbonate rocks (dolomite and massive limestones); 2 fine-grained sedimentary and metamorphic rocks (schists, calc-schists, mica schists, slate, phyllites and quartzites); 3 massive crystalline rocks (granites, granodiorites). Their main characteristics are illustrated by three case studies concerning large debris-flow events that occurred in the recent past. The comparison of sediment texture and grain-size distribution indicates that important differences in the sedimentological features of debris flows are generated by the three different rock types in the catchments. Colluvium lithology strongly controls the grain-size distribution of the debris available on the catchment that is mobilized, transported and accumulated on the fan during catastrophic flood events. The proportion of fine-grained particles (clay and fine silt) within the colluvium plays a key role in controlling the dominant primary sedimentary processes. The study of 23 flood events over the past 30 yr indicates that the catchments of group 1 and 2 fans produce large amounts of clay and fine silt, which typically can lead to the generation of cohesive sediment gravity flows. Group 3 fan catchments produce colluvium free of clay and fine silt that can be mobilized and transported by water flow processes, and which in extreme flood events usually are associated with non-cohesive sediment gravity flows.