Reconstruction of the rock fall/avalanche frequency in the Mont Blanc massif since the Last Glacial Maximum by means of TCND and reflectance spectroscopy.
Rockfalls and rock avalanches are active processes in the Mont Blanc massif, with infrastructure and alpinists at risk. Thanks to a network of observers (hut keepers, mountain guides, alpinists) set up in 2007 present rockfalls are well surveyed and documented. Rockfall frequency over the past 150 y...
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ftinsu:oai:HAL:hal-01757945v1 2024-04-28T08:36:09+00:00 Reconstruction of the rock fall/avalanche frequency in the Mont Blanc massif since the Last Glacial Maximum by means of TCND and reflectance spectroscopy. Gallach, Xavi Ogier, Christophe Ravanel, Ludovic Deline, Philip Carcaillet, Julien 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) Institut des Sciences de la Terre (ISTerre) Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement IRD : UR219-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ) Department of Physical Geography, Stockholm University Stockholm, Sweden 2016-06-08 https://sde.hal.science/hal-01757945 en eng HAL CCSD hal-01757945 https://sde.hal.science/hal-01757945 Third Nordic Workshop on cosmogenic nuclide techniques https://sde.hal.science/hal-01757945 Third Nordic Workshop on cosmogenic nuclide techniques, Department of Physical Geography, Stockholm University, Jun 2016, Stockholm, Sweden [SDE.BE]Environmental Sciences/Biodiversity and Ecology [SDE.ES]Environmental Sciences/Environment and Society [SDE.MCG]Environmental Sciences/Global Changes [SDE.IE]Environmental Sciences/Environmental Engineering [SHS.GEO]Humanities and Social Sciences/Geography info:eu-repo/semantics/conferenceObject Conference papers 2016 ftinsu 2024-04-05T00:46:12Z Rockfalls and rock avalanches are active processes in the Mont Blanc massif, with infrastructure and alpinists at risk. Thanks to a network of observers (hut keepers, mountain guides, alpinists) set up in 2007 present rockfalls are well surveyed and documented. Rockfall frequency over the past 150 years has been studied by comparison of historical photographs, showing that it strongly increased during the three last decades, especially during hot periods like the summer of 2003 and 2015, due to permafrost degradation driven by the climate change. In order to decipher the possible relationship between rockfall occurrence and the warmest periods of the Lateglacial and the Holocene, we start to study the morphodynamics of some selected high-elevated (>3000 m a.s.l.) rockwalls of the massif on a long timescale. Contrary to low altitude, deglaciated sites where study of large rockfall deposits allows to quantify frequency and magnitude of the process, rockfalls that detached from high-elevated rockwalls are no more noticeable as debris were absorbed and evacuated by the glaciers. Therefore, our study focuses on the rockfall scars. Their 10Be dating gives us the rock surface exposure age from present to far beyond the Last Glacial Maximum, interpreted as the rockfall ages. TCN dating of rockfalls has been carried out at the Aiguille du Midi in 2007 (Boehlert et al., 2008), and three other sites in the Mont Blanc massif in 2011 (Gallach et al., submitted). Here we present a new data set of rockfall dating carried out in 2015 that improves the 2007 and 2011 data. Furthermore, a relationship between the colour of the Mont Blanc granite and its exposure age has been shown: fresh rock surface is light grey (e.g. in recent rockfall scars) whereas weathered rock surface is in the range grey to orange/red: the redder a rock surface, the older its age. Here, reflectance spectroscopy is used to quantify the granite surface colour. Böhlert, R., Gruber, S., Egli, M., Maisch, M., Brandová, D., Haeberli, W., Ivy-Ochs, S., ... Conference Object permafrost Institut national des sciences de l'Univers: HAL-INSU |
institution |
Open Polar |
collection |
Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
English |
topic |
[SDE.BE]Environmental Sciences/Biodiversity and Ecology [SDE.ES]Environmental Sciences/Environment and Society [SDE.MCG]Environmental Sciences/Global Changes [SDE.IE]Environmental Sciences/Environmental Engineering [SHS.GEO]Humanities and Social Sciences/Geography |
spellingShingle |
[SDE.BE]Environmental Sciences/Biodiversity and Ecology [SDE.ES]Environmental Sciences/Environment and Society [SDE.MCG]Environmental Sciences/Global Changes [SDE.IE]Environmental Sciences/Environmental Engineering [SHS.GEO]Humanities and Social Sciences/Geography Gallach, Xavi Ogier, Christophe Ravanel, Ludovic Deline, Philip Carcaillet, Julien Reconstruction of the rock fall/avalanche frequency in the Mont Blanc massif since the Last Glacial Maximum by means of TCND and reflectance spectroscopy. |
topic_facet |
[SDE.BE]Environmental Sciences/Biodiversity and Ecology [SDE.ES]Environmental Sciences/Environment and Society [SDE.MCG]Environmental Sciences/Global Changes [SDE.IE]Environmental Sciences/Environmental Engineering [SHS.GEO]Humanities and Social Sciences/Geography |
description |
Rockfalls and rock avalanches are active processes in the Mont Blanc massif, with infrastructure and alpinists at risk. Thanks to a network of observers (hut keepers, mountain guides, alpinists) set up in 2007 present rockfalls are well surveyed and documented. Rockfall frequency over the past 150 years has been studied by comparison of historical photographs, showing that it strongly increased during the three last decades, especially during hot periods like the summer of 2003 and 2015, due to permafrost degradation driven by the climate change. In order to decipher the possible relationship between rockfall occurrence and the warmest periods of the Lateglacial and the Holocene, we start to study the morphodynamics of some selected high-elevated (>3000 m a.s.l.) rockwalls of the massif on a long timescale. Contrary to low altitude, deglaciated sites where study of large rockfall deposits allows to quantify frequency and magnitude of the process, rockfalls that detached from high-elevated rockwalls are no more noticeable as debris were absorbed and evacuated by the glaciers. Therefore, our study focuses on the rockfall scars. Their 10Be dating gives us the rock surface exposure age from present to far beyond the Last Glacial Maximum, interpreted as the rockfall ages. TCN dating of rockfalls has been carried out at the Aiguille du Midi in 2007 (Boehlert et al., 2008), and three other sites in the Mont Blanc massif in 2011 (Gallach et al., submitted). Here we present a new data set of rockfall dating carried out in 2015 that improves the 2007 and 2011 data. Furthermore, a relationship between the colour of the Mont Blanc granite and its exposure age has been shown: fresh rock surface is light grey (e.g. in recent rockfall scars) whereas weathered rock surface is in the range grey to orange/red: the redder a rock surface, the older its age. Here, reflectance spectroscopy is used to quantify the granite surface colour. Böhlert, R., Gruber, S., Egli, M., Maisch, M., Brandová, D., Haeberli, W., Ivy-Ochs, S., ... |
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) Institut des Sciences de la Terre (ISTerre) Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement IRD : UR219-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ) Department of Physical Geography, Stockholm University |
format |
Conference Object |
author |
Gallach, Xavi Ogier, Christophe Ravanel, Ludovic Deline, Philip Carcaillet, Julien |
author_facet |
Gallach, Xavi Ogier, Christophe Ravanel, Ludovic Deline, Philip Carcaillet, Julien |
author_sort |
Gallach, Xavi |
title |
Reconstruction of the rock fall/avalanche frequency in the Mont Blanc massif since the Last Glacial Maximum by means of TCND and reflectance spectroscopy. |
title_short |
Reconstruction of the rock fall/avalanche frequency in the Mont Blanc massif since the Last Glacial Maximum by means of TCND and reflectance spectroscopy. |
title_full |
Reconstruction of the rock fall/avalanche frequency in the Mont Blanc massif since the Last Glacial Maximum by means of TCND and reflectance spectroscopy. |
title_fullStr |
Reconstruction of the rock fall/avalanche frequency in the Mont Blanc massif since the Last Glacial Maximum by means of TCND and reflectance spectroscopy. |
title_full_unstemmed |
Reconstruction of the rock fall/avalanche frequency in the Mont Blanc massif since the Last Glacial Maximum by means of TCND and reflectance spectroscopy. |
title_sort |
reconstruction of the rock fall/avalanche frequency in the mont blanc massif since the last glacial maximum by means of tcnd and reflectance spectroscopy. |
publisher |
HAL CCSD |
publishDate |
2016 |
url |
https://sde.hal.science/hal-01757945 |
op_coverage |
Stockholm, Sweden |
genre |
permafrost |
genre_facet |
permafrost |
op_source |
Third Nordic Workshop on cosmogenic nuclide techniques https://sde.hal.science/hal-01757945 Third Nordic Workshop on cosmogenic nuclide techniques, Department of Physical Geography, Stockholm University, Jun 2016, Stockholm, Sweden |
op_relation |
hal-01757945 https://sde.hal.science/hal-01757945 |
_version_ |
1797568005034475520 |