Spontaneous Formation of an Internal Shear Band in Ice Flowing Over Topographically Variable Bedrock
Ice surface speed increases dramatically from upstream to downstream in many ice streams and glaciers. This speed-up is thought to be associated with a transition from internal distributed deformation to highly localized deformation or sliding at the ice-bedrock interface. The physical processes gov...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/667425 2024-05-12T08:04:38+00:00 Spontaneous Formation of an Internal Shear Band in Ice Flowing Over Topographically Variable Bedrock Liu, Emma Weijia Räss, Ludovic id_orcid:0 000-0002-1136-899X Herman, Frédéric Podladchikov, Yury Suckale, Jenny 2024-04 application/application/pdf https://hdl.handle.net/20.500.11850/667425 https://doi.org/10.3929/ethz-b-000667425 en eng Wiley info:eu-repo/semantics/altIdentifier/doi/10.1029/2022jf007040 info:eu-repo/semantics/altIdentifier/wos/001194733900001 http://hdl.handle.net/20.500.11850/667425 doi:10.3929/ethz-b-000667425 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by-nc-nd/4.0/ Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Journal of Geophysical Research: Earth Surface, 129 (4) info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2024 ftethz https://doi.org/20.500.11850/66742510.3929/ethz-b-00066742510.1029/2022jf007040 2024-04-17T14:25:36Z Ice surface speed increases dramatically from upstream to downstream in many ice streams and glaciers. This speed-up is thought to be associated with a transition from internal distributed deformation to highly localized deformation or sliding at the ice-bedrock interface. The physical processes governing this transition remain unclear. Here, we argue that highly localized deformation does not necessarily initiate at the ice-bedrock interface, but could also take the form of an internal shear band inside the ice flow that connects topographic highs. The power-law exponent n in the ice rheology amplifies the feedback between shear heating and shear localization, leading to the spontaneous formation of an internal shear band that can create flow separation within the ice. We model the thermomechanical ice flow over a sinusoidal basal topography by building on the high-resolution Stokes solver FastICE v1.0. We compile a regime diagram summarizing cases in which a sinusoidal topography with a given amplitude and wavelength leads to shear band formation for a given rheology. We compare our model results to borehole measurements from Greenland and find evidence to support the existence of an internal shear band. Our study highlights the importance of re-evaluating the degree to which internal deformation contributes to total deformation in the ice column and to the flow-to-sliding transition. ISSN:0148-0227 ISSN:2169-9003 ISSN:2169-9011 Article in Journal/Newspaper Greenland ETH Zürich Research Collection Greenland |
institution |
Open Polar |
collection |
ETH Zürich Research Collection |
op_collection_id |
ftethz |
language |
English |
description |
Ice surface speed increases dramatically from upstream to downstream in many ice streams and glaciers. This speed-up is thought to be associated with a transition from internal distributed deformation to highly localized deformation or sliding at the ice-bedrock interface. The physical processes governing this transition remain unclear. Here, we argue that highly localized deformation does not necessarily initiate at the ice-bedrock interface, but could also take the form of an internal shear band inside the ice flow that connects topographic highs. The power-law exponent n in the ice rheology amplifies the feedback between shear heating and shear localization, leading to the spontaneous formation of an internal shear band that can create flow separation within the ice. We model the thermomechanical ice flow over a sinusoidal basal topography by building on the high-resolution Stokes solver FastICE v1.0. We compile a regime diagram summarizing cases in which a sinusoidal topography with a given amplitude and wavelength leads to shear band formation for a given rheology. We compare our model results to borehole measurements from Greenland and find evidence to support the existence of an internal shear band. Our study highlights the importance of re-evaluating the degree to which internal deformation contributes to total deformation in the ice column and to the flow-to-sliding transition. ISSN:0148-0227 ISSN:2169-9003 ISSN:2169-9011 |
format |
Article in Journal/Newspaper |
author |
Liu, Emma Weijia Räss, Ludovic id_orcid:0 000-0002-1136-899X Herman, Frédéric Podladchikov, Yury Suckale, Jenny |
spellingShingle |
Liu, Emma Weijia Räss, Ludovic id_orcid:0 000-0002-1136-899X Herman, Frédéric Podladchikov, Yury Suckale, Jenny Spontaneous Formation of an Internal Shear Band in Ice Flowing Over Topographically Variable Bedrock |
author_facet |
Liu, Emma Weijia Räss, Ludovic id_orcid:0 000-0002-1136-899X Herman, Frédéric Podladchikov, Yury Suckale, Jenny |
author_sort |
Liu, Emma Weijia |
title |
Spontaneous Formation of an Internal Shear Band in Ice Flowing Over Topographically Variable Bedrock |
title_short |
Spontaneous Formation of an Internal Shear Band in Ice Flowing Over Topographically Variable Bedrock |
title_full |
Spontaneous Formation of an Internal Shear Band in Ice Flowing Over Topographically Variable Bedrock |
title_fullStr |
Spontaneous Formation of an Internal Shear Band in Ice Flowing Over Topographically Variable Bedrock |
title_full_unstemmed |
Spontaneous Formation of an Internal Shear Band in Ice Flowing Over Topographically Variable Bedrock |
title_sort |
spontaneous formation of an internal shear band in ice flowing over topographically variable bedrock |
publisher |
Wiley |
publishDate |
2024 |
url |
https://hdl.handle.net/20.500.11850/667425 https://doi.org/10.3929/ethz-b-000667425 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Journal of Geophysical Research: Earth Surface, 129 (4) |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1029/2022jf007040 info:eu-repo/semantics/altIdentifier/wos/001194733900001 http://hdl.handle.net/20.500.11850/667425 doi:10.3929/ethz-b-000667425 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by-nc-nd/4.0/ Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International |
op_doi |
https://doi.org/20.500.11850/66742510.3929/ethz-b-00066742510.1029/2022jf007040 |
_version_ |
1798846869679374336 |