Direct observations of a three million cubic meter rock-slope collapse with almost immediate initiation of ensuing debris flows ...
Catastrophic collapse of large rock slopes ranks as one of the most hazardous natural phenomena in mountain landscapes. The cascade of events, from rock-slope failure, to rock avalanche and the near-immediate release of debris flows has not previously been described from direct observations. We repo...
| Main Authors: | , , , , , , , , , |
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| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
ETH Zurich
2020
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.3929/ethz-b-000379987 http://hdl.handle.net/20.500.11850/379987 |
| Summary: | Catastrophic collapse of large rock slopes ranks as one of the most hazardous natural phenomena in mountain landscapes. The cascade of events, from rock-slope failure, to rock avalanche and the near-immediate release of debris flows has not previously been described from direct observations. We report on the 2017, 3.0 × 10^6 m3 failure on Pizzo Cengalo in Switzerland, which led to human casualties and 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. The resulting rock avalanche traveled for 3.2 km and removed over one million m3 of glacier ice and debris deposits from a previous rock avalanche in 2011. Whereas this entrainment did not lead to an unusually large runout distance, it favored debris flow activity from the 2017 rock avalanche deposits: the first debris flow occurred with a delay of 30 s followed by ten debris flows within 9.5 h and two ... : Geomorphology, 351 ... |
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