Rock temperature prior to failure: analysis of 209 rockfall events in the Mont Blanc massif (Western European Alps)
International audience Periglacial rock walls are affected by an increase in rockfall activity attributed to permafrost degradation. While recent laboratory tests have asserted the role of permafrost in bedrock stability, linking experimental findings to field applications is hindered by the difficu...
Published in: | Permafrost and Periglacial Processes |
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Language: | English |
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Online Access: | https://hal.science/hal-03024101 https://hal.science/hal-03024101/document https://hal.science/hal-03024101/file/PPP_Legay_Magnin_Ravanel_r%C3%A9vis%C3%A9e_no_track.pdf https://doi.org/10.1002/ppp.2110 |
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ftunivsavoie:oai:HAL:hal-03024101v1 2024-02-11T10:07:49+01:00 Rock temperature prior to failure: analysis of 209 rockfall events in the Mont Blanc massif (Western European Alps) Legay, A Magnin, Florence Ravanel, Ludovic Environnements, Dynamiques et Territoires de Montagne (EDYTEM) Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS) ANR-19-CE01-0018,WISPER,Processus thermo-mécaniques liés à l'eau et à la glace dans les fractures des parois alpines à permafrost(2019) 2021-06-16 https://hal.science/hal-03024101 https://hal.science/hal-03024101/document https://hal.science/hal-03024101/file/PPP_Legay_Magnin_Ravanel_r%C3%A9vis%C3%A9e_no_track.pdf https://doi.org/10.1002/ppp.2110 en eng HAL CCSD Wiley info:eu-repo/semantics/altIdentifier/doi/10.1002/ppp.2110 hal-03024101 https://hal.science/hal-03024101 https://hal.science/hal-03024101/document https://hal.science/hal-03024101/file/PPP_Legay_Magnin_Ravanel_r%C3%A9vis%C3%A9e_no_track.pdf doi:10.1002/ppp.2110 info:eu-repo/semantics/OpenAccess ISSN: 1045-6740 EISSN: 1099-1530 Permafrost and Periglacial Processes https://hal.science/hal-03024101 Permafrost and Periglacial Processes, 2021, 32 (3), pp.520-536. ⟨10.1002/ppp.2110⟩ rockfall alpine rockwall thermal modeling permafrost Mont Blanc massif [SDE.ES]Environmental Sciences/Environment and Society [SDE]Environmental Sciences [SDE.MCG]Environmental Sciences/Global Changes info:eu-repo/semantics/article Journal articles 2021 ftunivsavoie https://doi.org/10.1002/ppp.2110 2024-01-23T23:37:53Z International audience Periglacial rock walls are affected by an increase in rockfall activity attributed to permafrost degradation. While recent laboratory tests have asserted the role of permafrost in bedrock stability, linking experimental findings to field applications is hindered by the difficulty to assess bedrock temperature at observed rockfall locations and time. In this study, we simulated bedrock temperature for 209 rockfalls inventoried in the Mont Blanc massif between 2007 and 2015 and 209 000 random events artificially created at observed rockfall locations. Real and random events are then compared in a statistical analysis to determine the results significance. Permafrost conditions (or very close to 0 °C) were consistently found for all events with failure depth > 6 m, and for some events affecting depths from 4 to 6 m. Shallower events were likely not related to permafrost processes. Surface temperatures were significantly high up to at least 2 months prior to failure with the highest peaks in significance 1.5 to 2 months and 1 to 5 days before rockfalls. Similarly, temperature significances at scar depths were significantly high, but steadily decreasing, 1 day to 3 weeks before failure. The study confirms that warm permafrost areas (> -2 °C) are particularly prone to rockfalls, and that failures are a direct response to extraordinary high bedrock temperature in both frozen and unfrozen conditions. The results are promising for the development of a rockfall susceptibility index but uncertainty analysis encourages to use a greater rockfall sample and a different sample of random events. Article in Journal/Newspaper permafrost Permafrost and Periglacial Processes Université Savoie Mont Blanc: HAL Mont Blanc ENVELOPE(69.468,69.468,-49.461,-49.461) Permafrost and Periglacial Processes 32 3 520 536 |
institution |
Open Polar |
collection |
Université Savoie Mont Blanc: HAL |
op_collection_id |
ftunivsavoie |
language |
English |
topic |
rockfall alpine rockwall thermal modeling permafrost Mont Blanc massif [SDE.ES]Environmental Sciences/Environment and Society [SDE]Environmental Sciences [SDE.MCG]Environmental Sciences/Global Changes |
spellingShingle |
rockfall alpine rockwall thermal modeling permafrost Mont Blanc massif [SDE.ES]Environmental Sciences/Environment and Society [SDE]Environmental Sciences [SDE.MCG]Environmental Sciences/Global Changes Legay, A Magnin, Florence Ravanel, Ludovic Rock temperature prior to failure: analysis of 209 rockfall events in the Mont Blanc massif (Western European Alps) |
topic_facet |
rockfall alpine rockwall thermal modeling permafrost Mont Blanc massif [SDE.ES]Environmental Sciences/Environment and Society [SDE]Environmental Sciences [SDE.MCG]Environmental Sciences/Global Changes |
description |
International audience Periglacial rock walls are affected by an increase in rockfall activity attributed to permafrost degradation. While recent laboratory tests have asserted the role of permafrost in bedrock stability, linking experimental findings to field applications is hindered by the difficulty to assess bedrock temperature at observed rockfall locations and time. In this study, we simulated bedrock temperature for 209 rockfalls inventoried in the Mont Blanc massif between 2007 and 2015 and 209 000 random events artificially created at observed rockfall locations. Real and random events are then compared in a statistical analysis to determine the results significance. Permafrost conditions (or very close to 0 °C) were consistently found for all events with failure depth > 6 m, and for some events affecting depths from 4 to 6 m. Shallower events were likely not related to permafrost processes. Surface temperatures were significantly high up to at least 2 months prior to failure with the highest peaks in significance 1.5 to 2 months and 1 to 5 days before rockfalls. Similarly, temperature significances at scar depths were significantly high, but steadily decreasing, 1 day to 3 weeks before failure. The study confirms that warm permafrost areas (> -2 °C) are particularly prone to rockfalls, and that failures are a direct response to extraordinary high bedrock temperature in both frozen and unfrozen conditions. The results are promising for the development of a rockfall susceptibility index but uncertainty analysis encourages to use a greater rockfall sample and a different sample of random events. |
author2 |
Environnements, Dynamiques et Territoires de Montagne (EDYTEM) Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS) ANR-19-CE01-0018,WISPER,Processus thermo-mécaniques liés à l'eau et à la glace dans les fractures des parois alpines à permafrost(2019) |
format |
Article in Journal/Newspaper |
author |
Legay, A Magnin, Florence Ravanel, Ludovic |
author_facet |
Legay, A Magnin, Florence Ravanel, Ludovic |
author_sort |
Legay, A |
title |
Rock temperature prior to failure: analysis of 209 rockfall events in the Mont Blanc massif (Western European Alps) |
title_short |
Rock temperature prior to failure: analysis of 209 rockfall events in the Mont Blanc massif (Western European Alps) |
title_full |
Rock temperature prior to failure: analysis of 209 rockfall events in the Mont Blanc massif (Western European Alps) |
title_fullStr |
Rock temperature prior to failure: analysis of 209 rockfall events in the Mont Blanc massif (Western European Alps) |
title_full_unstemmed |
Rock temperature prior to failure: analysis of 209 rockfall events in the Mont Blanc massif (Western European Alps) |
title_sort |
rock temperature prior to failure: analysis of 209 rockfall events in the mont blanc massif (western european alps) |
publisher |
HAL CCSD |
publishDate |
2021 |
url |
https://hal.science/hal-03024101 https://hal.science/hal-03024101/document https://hal.science/hal-03024101/file/PPP_Legay_Magnin_Ravanel_r%C3%A9vis%C3%A9e_no_track.pdf https://doi.org/10.1002/ppp.2110 |
long_lat |
ENVELOPE(69.468,69.468,-49.461,-49.461) |
geographic |
Mont Blanc |
geographic_facet |
Mont Blanc |
genre |
permafrost Permafrost and Periglacial Processes |
genre_facet |
permafrost Permafrost and Periglacial Processes |
op_source |
ISSN: 1045-6740 EISSN: 1099-1530 Permafrost and Periglacial Processes https://hal.science/hal-03024101 Permafrost and Periglacial Processes, 2021, 32 (3), pp.520-536. ⟨10.1002/ppp.2110⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1002/ppp.2110 hal-03024101 https://hal.science/hal-03024101 https://hal.science/hal-03024101/document https://hal.science/hal-03024101/file/PPP_Legay_Magnin_Ravanel_r%C3%A9vis%C3%A9e_no_track.pdf doi:10.1002/ppp.2110 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1002/ppp.2110 |
container_title |
Permafrost and Periglacial Processes |
container_volume |
32 |
container_issue |
3 |
container_start_page |
520 |
op_container_end_page |
536 |
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1790606572041273344 |