Geomorphology 351 (2020) 106933
Geomorphology 351 (2020) 106933 Contents lists available at ScienceDirect Geomorphology journal homepage: www.elsevier.com/locate/geomorph Direct observations of a three million cubic meter rock-slope collapse with almost immediate initiation of ensuing debris flows a,∗ b c d d Fabian Walter , Florian Amann , Andrew Kos , Robert Kenner , Marcia Phillips , e a,f g h h Antoine de Preux , Matthias Huss , Christian Tognacca , John Clinton , Tobias Diehl , i Yves Bonanomi a Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, Zurich, Switzerland b Chair of Engineering Geology and Hydrogeology, RWTH Aachen University, Germany c Terrasense Switzerland Ltd, Buchs SG, Switzerland d WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland e Marti AG, Bern, Switzerland f Department of Geosciences, University of Fribourg, Fribourg, Switzerland g Beffa Tognacca Gmbh, Switzerland h Swiss Seismological Service, ETH Zurich, Zurich, Switzerland i Bonanomi AG, Igis, Switzerland a r t i c l e i n f o a b s t r a c t Article history: Catastrophic collapse of large rock slopes ranks as one of the most hazardous natural phenomena in Received 26 June 2019 mountain landscapes. The cascade of events, from rock-slope failure, to rock avalanche and the near- Received in revised form 29 October 2019 immediate release of debris flows has not previously been described from direct observations. We report Accepted 30 October 2019 6 3 on the 2017, 3.0 × 10 m failure on Pizzo Cengalo in Switzerland, which led to human casualties and Available online 2 November 2019 significant damage to infrastructure. Based on remote sensing and field investigations, we find a change in critical slope stability prior to failure for which permafrost may have played a destabilizing role.
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