Current glacier recession causes significant rockfall increase: the immediate paraglacial response of deglaciating cirque walls
In the European Alps, almost half the glacier volume has disappeared over the past 150 years. The loss is reflected in glacier retreat and ice surface lowering even at high altitude. In steep glacial cirques, surface lowering exposes rock to atmospheric conditions probably for the very first time in...
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ftcopernicus:oai:publications.copernicus.org:esurf83425 2023-05-15T16:37:53+02:00 Current glacier recession causes significant rockfall increase: the immediate paraglacial response of deglaciating cirque walls Hartmeyer, Ingo Delleske, Robert Keuschnig, Markus Krautblatter, Michael Lang, Andreas Schrott, Lothar Otto, Jan-Christoph 2020-09-11 application/pdf https://doi.org/10.5194/esurf-8-729-2020 https://esurf.copernicus.org/articles/8/729/2020/ eng eng doi:10.5194/esurf-8-729-2020 https://esurf.copernicus.org/articles/8/729/2020/ eISSN: 2196-632X Text 2020 ftcopernicus https://doi.org/10.5194/esurf-8-729-2020 2020-09-14T16:22:13Z In the European Alps, almost half the glacier volume has disappeared over the past 150 years. The loss is reflected in glacier retreat and ice surface lowering even at high altitude. In steep glacial cirques, surface lowering exposes rock to atmospheric conditions probably for the very first time in several millennia. Instability of rockwalls has long been identified as one of the direct consequences of deglaciation, but so far cirque-wide quantification of rockfall at high resolution is missing. Based on terrestrial lidar, a rockfall inventory for the permafrost-affected rockwalls of two rapidly deglaciating cirques in the Central Alps of Austria (Kitzsteinhorn) is established. Over 6 years (2011–2017), 78 rockwall scans were acquired to generate data of high spatial and temporal resolution. Overall, 632 rockfalls were registered, ranging from 0.003 to 879.4 m 3 , mainly originating from pre-existing structural rock weaknesses. A total of 60 % of the rockfall volume detached from less than 10 vertical metres above the glacier surface, indicating enhanced rockfall activity over tens of years following deglaciation. Debuttressing seems to play a minor effect only. Rather, preconditioning is assumed to start inside the randkluft (void between cirque wall and glacier) where measured sustained freezing and ample supply of liquid water likely cause enhanced physical weathering and high quarrying stresses. Following deglaciation, pronounced thermomechanical strain is induced and an active layer penetrates into the formerly perennially frozen bedrock. These factors likely cause the observed paraglacial rockfall increase close to the glacier surface. This paper, the first of two companion pieces, presents the most extensive dataset of high-alpine rockfall to date and the first systematic documentation of a cirque-wide erosion response of glaciated rockwalls to recent climate warming. Text Ice permafrost Copernicus Publications: E-Journals Earth Surface Dynamics 8 3 729 751 |
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English |
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In the European Alps, almost half the glacier volume has disappeared over the past 150 years. The loss is reflected in glacier retreat and ice surface lowering even at high altitude. In steep glacial cirques, surface lowering exposes rock to atmospheric conditions probably for the very first time in several millennia. Instability of rockwalls has long been identified as one of the direct consequences of deglaciation, but so far cirque-wide quantification of rockfall at high resolution is missing. Based on terrestrial lidar, a rockfall inventory for the permafrost-affected rockwalls of two rapidly deglaciating cirques in the Central Alps of Austria (Kitzsteinhorn) is established. Over 6 years (2011–2017), 78 rockwall scans were acquired to generate data of high spatial and temporal resolution. Overall, 632 rockfalls were registered, ranging from 0.003 to 879.4 m 3 , mainly originating from pre-existing structural rock weaknesses. A total of 60 % of the rockfall volume detached from less than 10 vertical metres above the glacier surface, indicating enhanced rockfall activity over tens of years following deglaciation. Debuttressing seems to play a minor effect only. Rather, preconditioning is assumed to start inside the randkluft (void between cirque wall and glacier) where measured sustained freezing and ample supply of liquid water likely cause enhanced physical weathering and high quarrying stresses. Following deglaciation, pronounced thermomechanical strain is induced and an active layer penetrates into the formerly perennially frozen bedrock. These factors likely cause the observed paraglacial rockfall increase close to the glacier surface. This paper, the first of two companion pieces, presents the most extensive dataset of high-alpine rockfall to date and the first systematic documentation of a cirque-wide erosion response of glaciated rockwalls to recent climate warming. |
format |
Text |
author |
Hartmeyer, Ingo Delleske, Robert Keuschnig, Markus Krautblatter, Michael Lang, Andreas Schrott, Lothar Otto, Jan-Christoph |
spellingShingle |
Hartmeyer, Ingo Delleske, Robert Keuschnig, Markus Krautblatter, Michael Lang, Andreas Schrott, Lothar Otto, Jan-Christoph Current glacier recession causes significant rockfall increase: the immediate paraglacial response of deglaciating cirque walls |
author_facet |
Hartmeyer, Ingo Delleske, Robert Keuschnig, Markus Krautblatter, Michael Lang, Andreas Schrott, Lothar Otto, Jan-Christoph |
author_sort |
Hartmeyer, Ingo |
title |
Current glacier recession causes significant rockfall increase: the immediate paraglacial response of deglaciating cirque walls |
title_short |
Current glacier recession causes significant rockfall increase: the immediate paraglacial response of deglaciating cirque walls |
title_full |
Current glacier recession causes significant rockfall increase: the immediate paraglacial response of deglaciating cirque walls |
title_fullStr |
Current glacier recession causes significant rockfall increase: the immediate paraglacial response of deglaciating cirque walls |
title_full_unstemmed |
Current glacier recession causes significant rockfall increase: the immediate paraglacial response of deglaciating cirque walls |
title_sort |
current glacier recession causes significant rockfall increase: the immediate paraglacial response of deglaciating cirque walls |
publishDate |
2020 |
url |
https://doi.org/10.5194/esurf-8-729-2020 https://esurf.copernicus.org/articles/8/729/2020/ |
genre |
Ice permafrost |
genre_facet |
Ice permafrost |
op_source |
eISSN: 2196-632X |
op_relation |
doi:10.5194/esurf-8-729-2020 https://esurf.copernicus.org/articles/8/729/2020/ |
op_doi |
https://doi.org/10.5194/esurf-8-729-2020 |
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Earth Surface Dynamics |
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8 |
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3 |
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729 |
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751 |
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1766028189806624768 |