Repeated Holocene rock avalanches onto the Brenva Glacier, Mont Blanc massif, Italy: A chronology
International audience Infrequent rock avalanches (volume ≥1 Mm3) are long-runout processes, especially when travelling onto a glacier, that may threaten populated mountain valleys. Rock avalanches also have strong implications are for relief generation and destruction though time. Both consequences...
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ftunigrenoble:oai:HAL:hal-01349722v1 2024-09-15T18:11:35+00:00 Repeated Holocene rock avalanches onto the Brenva Glacier, Mont Blanc massif, Italy: A chronology Deline, Philip Akçar, Naki Ivy-Ochs, Susan Kubik, Peter W. 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) Institute of Geological Sciences Bern Universität Bern = University of Bern = Université de Berne (UNIBE) Institute of Particle Physics Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology Zürich (ETH Zürich) 2015 https://hal.science/hal-01349722 en eng HAL CCSD Elsevier hal-01349722 https://hal.science/hal-01349722 ISSN: 0277-3791 EISSN: 1873-457X Quaternary Science Reviews https://hal.science/hal-01349722 Quaternary Science Reviews, 2015, 126, pp.186-200 Rock avalanche Glacier Moraine Permafrost Radiocarbon dating Surface exposure dating 10Be Historical sources Holocene [SDE.MCG]Environmental Sciences/Global Changes [SDE.BE]Environmental Sciences/Biodiversity and Ecology [SDE.IE]Environmental Sciences/Environmental Engineering [SDE.ES]Environmental Sciences/Environment and Society [SHS.GEO]Humanities and Social Sciences/Geography info:eu-repo/semantics/article Journal articles 2015 ftunigrenoble 2024-07-29T23:39:57Z International audience Infrequent rock avalanches (volume ≥1 Mm3) are long-runout processes, especially when travelling onto a glacier, that may threaten populated mountain valleys. Rock avalanches also have strong implications are for relief generation and destruction though time. Both consequences make reconstruction and dating of past events crucial, but dense clusters of events documented in one basin that may improve our knowledge of rock-avalanche frequency and triggering are very rare. Here we propose a chronology of seven of the rock-ice avalanches that affected a steep glacier basin on the southeast side of the Mont Blanc during the late Holocene. A geomorphological study of the runout deposits on the valley floor and the opposite side was combined with the analysis of historical sources and the use of absolute and relative dating methods, especially surface exposure dating with cosmogenic nuclides of 18 granite boulders from two deposits.These rock-ice avalanches are dated AD 1997 and 1920, with a rock volume in the range 2.4–3.6 and 2 × 106 m3, respectively; AD 1767, with a slightly shorter runout; AD 1000–1200, with a longer runout; c. AD 500, the runout of which is uncertain; c. 2500 BP, the determination of which is indirect; and c. 3500 years, with the longest runout.There is no distinct relationship between climatic periods and occurrence of these rock avalanches. Even for the two best documented ones, modelling suggests that the 1997 scar was characterized by a permafrost close to 0 °C, whereas in contrast, the 1920 scar was on the contrary located in cold permafrost. Article in Journal/Newspaper Ice permafrost Université Grenoble Alpes: HAL |
institution |
Open Polar |
collection |
Université Grenoble Alpes: HAL |
op_collection_id |
ftunigrenoble |
language |
English |
topic |
Rock avalanche Glacier Moraine Permafrost Radiocarbon dating Surface exposure dating 10Be Historical sources Holocene [SDE.MCG]Environmental Sciences/Global Changes [SDE.BE]Environmental Sciences/Biodiversity and Ecology [SDE.IE]Environmental Sciences/Environmental Engineering [SDE.ES]Environmental Sciences/Environment and Society [SHS.GEO]Humanities and Social Sciences/Geography |
spellingShingle |
Rock avalanche Glacier Moraine Permafrost Radiocarbon dating Surface exposure dating 10Be Historical sources Holocene [SDE.MCG]Environmental Sciences/Global Changes [SDE.BE]Environmental Sciences/Biodiversity and Ecology [SDE.IE]Environmental Sciences/Environmental Engineering [SDE.ES]Environmental Sciences/Environment and Society [SHS.GEO]Humanities and Social Sciences/Geography Deline, Philip Akçar, Naki Ivy-Ochs, Susan Kubik, Peter W. Repeated Holocene rock avalanches onto the Brenva Glacier, Mont Blanc massif, Italy: A chronology |
topic_facet |
Rock avalanche Glacier Moraine Permafrost Radiocarbon dating Surface exposure dating 10Be Historical sources Holocene [SDE.MCG]Environmental Sciences/Global Changes [SDE.BE]Environmental Sciences/Biodiversity and Ecology [SDE.IE]Environmental Sciences/Environmental Engineering [SDE.ES]Environmental Sciences/Environment and Society [SHS.GEO]Humanities and Social Sciences/Geography |
description |
International audience Infrequent rock avalanches (volume ≥1 Mm3) are long-runout processes, especially when travelling onto a glacier, that may threaten populated mountain valleys. Rock avalanches also have strong implications are for relief generation and destruction though time. Both consequences make reconstruction and dating of past events crucial, but dense clusters of events documented in one basin that may improve our knowledge of rock-avalanche frequency and triggering are very rare. Here we propose a chronology of seven of the rock-ice avalanches that affected a steep glacier basin on the southeast side of the Mont Blanc during the late Holocene. A geomorphological study of the runout deposits on the valley floor and the opposite side was combined with the analysis of historical sources and the use of absolute and relative dating methods, especially surface exposure dating with cosmogenic nuclides of 18 granite boulders from two deposits.These rock-ice avalanches are dated AD 1997 and 1920, with a rock volume in the range 2.4–3.6 and 2 × 106 m3, respectively; AD 1767, with a slightly shorter runout; AD 1000–1200, with a longer runout; c. AD 500, the runout of which is uncertain; c. 2500 BP, the determination of which is indirect; and c. 3500 years, with the longest runout.There is no distinct relationship between climatic periods and occurrence of these rock avalanches. Even for the two best documented ones, modelling suggests that the 1997 scar was characterized by a permafrost close to 0 °C, whereas in contrast, the 1920 scar was on the contrary located in cold permafrost. |
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) Institute of Geological Sciences Bern Universität Bern = University of Bern = Université de Berne (UNIBE) Institute of Particle Physics Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology Zürich (ETH Zürich) |
format |
Article in Journal/Newspaper |
author |
Deline, Philip Akçar, Naki Ivy-Ochs, Susan Kubik, Peter W. |
author_facet |
Deline, Philip Akçar, Naki Ivy-Ochs, Susan Kubik, Peter W. |
author_sort |
Deline, Philip |
title |
Repeated Holocene rock avalanches onto the Brenva Glacier, Mont Blanc massif, Italy: A chronology |
title_short |
Repeated Holocene rock avalanches onto the Brenva Glacier, Mont Blanc massif, Italy: A chronology |
title_full |
Repeated Holocene rock avalanches onto the Brenva Glacier, Mont Blanc massif, Italy: A chronology |
title_fullStr |
Repeated Holocene rock avalanches onto the Brenva Glacier, Mont Blanc massif, Italy: A chronology |
title_full_unstemmed |
Repeated Holocene rock avalanches onto the Brenva Glacier, Mont Blanc massif, Italy: A chronology |
title_sort |
repeated holocene rock avalanches onto the brenva glacier, mont blanc massif, italy: a chronology |
publisher |
HAL CCSD |
publishDate |
2015 |
url |
https://hal.science/hal-01349722 |
genre |
Ice permafrost |
genre_facet |
Ice permafrost |
op_source |
ISSN: 0277-3791 EISSN: 1873-457X Quaternary Science Reviews https://hal.science/hal-01349722 Quaternary Science Reviews, 2015, 126, pp.186-200 |
op_relation |
hal-01349722 https://hal.science/hal-01349722 |
_version_ |
1810449180368306176 |