Contemporary glacier retreat triggers a rapid landslide response, Great Aletsch Glacier, Switzerland

Abstract

Abstract The destabilization and catastrophic failure of landslides triggered by retreating glaciers is an expected outcome of global climate change and poses a significant threat to inhabitants of glaciated mountain valleys around the globe. Of particular importance are the formation of landslide‐dammed lakes, outburst floods, and related sediment entrainment. Based on field observations and remote sensing of a deep‐seated landslide, located at the present‐day terminus of the Great Aletsch Glacier, we show that the spatiotemporal response of the landslide to glacier retreat is rapid, occurring within a decade. Our observations uniquely capture the critical period of increase in slope deformations, onset of failure, and show that measured displacements at the crown and toe regions of the landslide demonstrate a feedback mechanism between glacier ice reduction and response of the entire landslide body. These observations shed new light on the geomorphological processes of landslide response in paraglacial environments, which were previously understood to occur over significantly longer time periods.