Crevasse-induced Rayleigh-wave azimuthal anisotropy on Glacier de la Plaine Morte, Switzerland
Crevasses and englacial fracture networks route meltwater from a glacier's surface to the subglacial drainage system and thus influence glacial hydraulics. However, rapid fracture growth may also lead to sudden and potentially hazardous structural failure of unstable glaciers and ice dams, rift...
Published in: | Annals of Glaciology |
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Format: | Article in Journal/Newspaper |
Language: | English |
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2019
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Online Access: | https://gfzpublic.gfz-potsdam.de/pubman/item/item_5003669 |
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ftgfzpotsdam:oai:gfzpublic.gfz-potsdam.de:item_5003669 2023-05-15T13:29:12+02:00 Crevasse-induced Rayleigh-wave azimuthal anisotropy on Glacier de la Plaine Morte, Switzerland Lindner, F. Laske, G. Walter, F. Doran, A. 2019 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5003669 eng eng info:eu-repo/semantics/altIdentifier/doi/10.1017/aog.2018.25 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5003669 Annals of Glaciology info:eu-repo/semantics/article 2019 ftgfzpotsdam https://doi.org/10.1017/aog.2018.25 2022-09-14T05:57:25Z Crevasses and englacial fracture networks route meltwater from a glacier's surface to the subglacial drainage system and thus influence glacial hydraulics. However, rapid fracture growth may also lead to sudden and potentially hazardous structural failure of unstable glaciers and ice dams, rifting of ice shelves, or iceberg calving. Here, we use passive seismic recordings to investigate the englacial fracture network on Glacier de la Plaine Morte, Switzerland. Glacier dynamics and the drainage of an ice-marginal lake give rise to numerous icequakes, the majority of which generate dispersed, high-frequency Rayleigh waves. A wide distribution of events allows us to study azimuthal anisotropy between 10 and 30 Hz in order to extract englacial seismic velocities in regions of preferentially oriented crevasses. Beamforming applied to a 100-m-aperture array reveals azimuthal anisotropy of Rayleigh-wave phase velocities reaching a strength of 8% at high frequencies. In addition, we find that the fast direction of wave propagation coincides with the observed surface strike of the narrow crevasses. Forward modeling and inversion of dispersion curves suggest that the azimuthal anisotropy is induced by a 40-m-thick crevassed layer at the surface of the glacier with 8% anisotropy in shear-wave velocity. Article in Journal/Newspaper Annals of Glaciology Ice Shelves GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) Marginal Lake ENVELOPE(163.500,163.500,-74.600,-74.600) Annals of Glaciology 60 79 96 111 |
institution |
Open Polar |
collection |
GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) |
op_collection_id |
ftgfzpotsdam |
language |
English |
description |
Crevasses and englacial fracture networks route meltwater from a glacier's surface to the subglacial drainage system and thus influence glacial hydraulics. However, rapid fracture growth may also lead to sudden and potentially hazardous structural failure of unstable glaciers and ice dams, rifting of ice shelves, or iceberg calving. Here, we use passive seismic recordings to investigate the englacial fracture network on Glacier de la Plaine Morte, Switzerland. Glacier dynamics and the drainage of an ice-marginal lake give rise to numerous icequakes, the majority of which generate dispersed, high-frequency Rayleigh waves. A wide distribution of events allows us to study azimuthal anisotropy between 10 and 30 Hz in order to extract englacial seismic velocities in regions of preferentially oriented crevasses. Beamforming applied to a 100-m-aperture array reveals azimuthal anisotropy of Rayleigh-wave phase velocities reaching a strength of 8% at high frequencies. In addition, we find that the fast direction of wave propagation coincides with the observed surface strike of the narrow crevasses. Forward modeling and inversion of dispersion curves suggest that the azimuthal anisotropy is induced by a 40-m-thick crevassed layer at the surface of the glacier with 8% anisotropy in shear-wave velocity. |
format |
Article in Journal/Newspaper |
author |
Lindner, F. Laske, G. Walter, F. Doran, A. |
spellingShingle |
Lindner, F. Laske, G. Walter, F. Doran, A. Crevasse-induced Rayleigh-wave azimuthal anisotropy on Glacier de la Plaine Morte, Switzerland |
author_facet |
Lindner, F. Laske, G. Walter, F. Doran, A. |
author_sort |
Lindner, F. |
title |
Crevasse-induced Rayleigh-wave azimuthal anisotropy on Glacier de la Plaine Morte, Switzerland |
title_short |
Crevasse-induced Rayleigh-wave azimuthal anisotropy on Glacier de la Plaine Morte, Switzerland |
title_full |
Crevasse-induced Rayleigh-wave azimuthal anisotropy on Glacier de la Plaine Morte, Switzerland |
title_fullStr |
Crevasse-induced Rayleigh-wave azimuthal anisotropy on Glacier de la Plaine Morte, Switzerland |
title_full_unstemmed |
Crevasse-induced Rayleigh-wave azimuthal anisotropy on Glacier de la Plaine Morte, Switzerland |
title_sort |
crevasse-induced rayleigh-wave azimuthal anisotropy on glacier de la plaine morte, switzerland |
publishDate |
2019 |
url |
https://gfzpublic.gfz-potsdam.de/pubman/item/item_5003669 |
long_lat |
ENVELOPE(163.500,163.500,-74.600,-74.600) |
geographic |
Marginal Lake |
geographic_facet |
Marginal Lake |
genre |
Annals of Glaciology Ice Shelves |
genre_facet |
Annals of Glaciology Ice Shelves |
op_source |
Annals of Glaciology |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1017/aog.2018.25 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5003669 |
op_doi |
https://doi.org/10.1017/aog.2018.25 |
container_title |
Annals of Glaciology |
container_volume |
60 |
container_issue |
79 |
container_start_page |
96 |
op_container_end_page |
111 |
_version_ |
1765999258034503680 |