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The 1963 Vajont Slide was an unparalleled natural disaster; it produced a displacement wave that overtopped the Vajont Dam and destroyed several villages, with the loss of over 2000 lives. In the aftermath of this catastrophe, numerous researchers have attempted to understand the mechanisms and behaviour of the landslide. This paper presents the results of the first detailed digital photogrammetric survey of the Vajont failure surface. Discontinuity orientations were detected and eight discontinuity sets were characterised. Surface morphology profiles reveal several scales of roughness and folding, from a regional-scale syncline to small-scale roughness, all of which played a significant role in failure behaviour.

We present a workflow for investigating large, slow-moving landslides which combines the synthetic aperture radar (SAR) technique, GIS post-processing, and airborne laser scanning (ALS), and apply it to Fels landslide in Alaska, US. First, we exploit a speckle tracking (ST) approach to derive the easting, northing, and vertical components of the displacement vectors across the rock slope for two five-year windows, 2010–2015 and 2015–2020. Then, we perform post-processing in a GIS environment to derive displacement magnitude, trend, and plunge maps of the landslide area. Finally, we compare the ST-derived displacement data with structural lineament maps and profiles extracted from the ALS dataset. Relying on remotely sensed data, we estimate that the thickness of the slide mass is more than 100 m and displacements occur through a combination of slumping at the toe and planar sliding in the central and upper slope. Our approach provides information and interpretations that can assist in optimizing and planning fieldwork activities and site investigations at landslides in remote locations.

The relationship between landslides and rock mass strength is fundamental for assessing landslide hazards. Some researchers have proposed that there is an inverse relationship between the number of landslides and rock mass strength. However, in some tectonically active mountain ranges, higher rates of landsliding appear to be associated with greater rock mass strength. We investigated the relation between landslides and rock mass strength in the Langxian (LX), Lulang (LL), and Tongmai (TM) regions in southeastern Tibet by identifying and mapping 294 large bedrock landslides using 10-m resolution lidar bare-earth imagery. An inverse relationship between topographic relief and the slope angle of historical landslides demonstrates that rock mass strength is an important factor controlling relief in the study area. Applying Culmann's method, we back-calculated rock mass strengths ranging from 60 to 770 kPa at the landscape scale. Our data show that, at the landscape scale, more landslides have occurred on the hillslopes with greater rock mass strength than on those with lower rock mass strength. We conclude that the stability of slopes in our study areas is controlled by rock mass strength, but the dominant drivers of failure are rock uplift and river incision, rather than a reduction in rock strength as has been proposed in some tectonically passive regions.

International audience; Rock mass movements are dominant in the morphodynamics of high Alpine rock slopes and are at the origin of significant risks for people who attend these areas and for infrastructures that are built on (e.g. huts, cable cars). These risks are increasing because of permafrost degradation and glacier retreat as consequences of the global warming. These two factors may affect slope stability by changing mechanical properties of the interstitial ice and modifying the mechanical constraints in these rock slopes. The monitoring of rock slopes is thus an essential element for risk management. Our study focuses on two particularly active areas of the Western Alps: the lower Arête des Cosmiques (3613 m a.s.l., Mont Blanc massif, France) on which is located the very popular Refuge des Cosmiques, and the Col des Gentianes (2894 m a.s.l., Valais, Switzerland) where is located a cable car station. Discussed on the basis of geophysical and glaciological data, the evolutions monitored by terrestrial laser scanning probably result from the combination between permafrost activity/degradation and glacier shrinkage.

Climate change and increased skier density is increasing ski run reworking, use of artificial snow and snow grooming. Few studies are available on these engineering impacts on slope stability. Therefore, the soil properties, compaction and infiltration characteristics were investigated on ski slopes and compared to natural sites for three different ski resorts (Les Menuires, La Rosière and Foppolo) in the French and Italian Alps. The results show that soil properties differ substantially, with lower nitrogen and carbon content and higher pH on ski runs. Soil compaction is up to three times higher and infiltration takes up to four times longer on ski slopes compared to natural sites. Some new ski slopes were even 100 % impermeable. This explains why ski slopes are more prone to landslides, sheet, rill and gully erosion and have a distinct vegetation cover.