The 2006 Collapse of the Bérard Rock Glacier (Southern French Alps)

Abstract

In the Mediterranean French Alps, the Bérard rock glacier suddenly collapsed during the summer of 2006; this was a rarely documented event in the world, exceptional for the amount of disturbed material (estimated at 250 000–500 000 m3). Located near the lower limit of permafrost, the Bérard rock glacier collapse might exemplify the possible consequences of the degradation of ice‐rich mountain permafrost. The causes of the collapse may include long‐term atmospheric warming, recent air temperature anomalies, niveo‐meteorological conditions prior to the collapse, geological settings and topographical context. Geomorphological interpretations and analysis of climatic data‐sets allow us to specify the different stages of the collapse and discuss the respective roles of the geological and hydro‐climatic factors and unfrozen water in the ground which could have led to the collapse. Geophysical measurements and ice observations in the scarp reveal that the internal structure of the intact part of the rock glacier is composed of both ice‐cemented and massive‐ice layers. The rock glacier also contains a high proportion of fine material (essentially silt and clay), which could have played an important role in the collapse. Geodetic measurements repeated since 2007 show that, with the exception of the upper part, the whole rock glacier was still experiencing destabilisation in 2010, with very high deformation rates exceeding 30 m in 3 years. The continuous monitoring of surface displacement carried out during the summer of 2007 has not shown any clear meteorological control on the post‐collapse rock glacier dynamics. Copyright © 2016 John Wiley & Sons, Ltd.

Kinematic investigations on the Furggwanghorn Rock Glacier, Switzerland

“…Understanding the thermal state and the kinematic behaviour of rock glaciers is essential for assessing hazards and limiting risks to infrastructure and human activities. Several past mass‐movement events have occurred in warm rock glaciers (eg, Val Pola in Italy in 1997, and the Bérard rock glacier in France; ), where heavy rainfall can trigger downslope transport of large volumes of soil …”

Mountain permafrost and associated geomorphological processes: recent changes in the French Alps

“…To date, the detachment of the Bérard rock glacier (Fig. 8c) Mountain permafrost and associated geomorphological processes: recent changes... in the French Alps is one of only two known cases in the world (Bodin et al, 2012;Bodin et al, accepted . Cryokarstic processes 25 One of the effects of ice loss due to permafrost degradation is the development of "cryokarstic" phenomena, i.e.…”

Multi-Annual Kinematics of an Active Rock Glacier Quantified from Very High-Resolution DEMs: An Application-Case in the French Alps

“…In the Alps, synchronous inter-annual fluctuations of surface velocities have been observed on many rock glaciers, suggesting a control of the ground thermal state on the deformation rate of the permafrost [3,4]. Some cases of rock glaciers' destabilization were also observed in various mountain chains, such as in the Alps [5,6] or in the Andes [7], becoming a potential source of hazards [8]. These temporal changes in rock glaciers' deformation patterns pointed out various mechanical processes involved in their behavior [9].…”