Stress Redistribution Explains Anti-correlated Subglacial Pressure Variations
We used a finite element model to interpret anti-correlated pressure variations at the base of a glacier to demonstrate the importance of stress redistribution in the basal ice. We first investigated two pairs of load cells installed 20 m apart at the base of the 210 m thick Engabreen glacier in Nor...
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Online Access: | https://doi.org/10.3389/feart.2017.00110 https://doaj.org/article/31b869e40e274d8fbd3df5cda6f36e93 |
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ftdoajarticles:oai:doaj.org/article:31b869e40e274d8fbd3df5cda6f36e93 2023-05-15T16:21:56+02:00 Stress Redistribution Explains Anti-correlated Subglacial Pressure Variations Pierre-Marie Lefeuvre Thomas Zwinger Miriam Jackson Olivier Gagliardini Gaute Lappegard Jon Ove Hagen 2018-01-01T00:00:00Z https://doi.org/10.3389/feart.2017.00110 https://doaj.org/article/31b869e40e274d8fbd3df5cda6f36e93 EN eng Frontiers Media S.A. http://journal.frontiersin.org/article/10.3389/feart.2017.00110/full https://doaj.org/toc/2296-6463 2296-6463 doi:10.3389/feart.2017.00110 https://doaj.org/article/31b869e40e274d8fbd3df5cda6f36e93 Frontiers in Earth Science, Vol 5 (2018) subglacial processes glacier hydrology glacier mechanics glacier modelling Svartisen Subglacial Laboratory Engabreen Science Q article 2018 ftdoajarticles https://doi.org/10.3389/feart.2017.00110 2022-12-31T07:21:33Z We used a finite element model to interpret anti-correlated pressure variations at the base of a glacier to demonstrate the importance of stress redistribution in the basal ice. We first investigated two pairs of load cells installed 20 m apart at the base of the 210 m thick Engabreen glacier in Northern Norway. The load cell data for July 2003 showed that pressurisation of a subglacial channel located over one load cell pair led to anti-correlation in pressure between the two pairs. To investigate the cause of this anti-correlation, we used a full Stokes 3D model of a 210 m thick and 25–200 m wide glacier with a pressurised subglacial channel represented as a pressure boundary condition. The model reproduced the anti-correlated pressure response at the glacier bed and variations in pressure of the same order of magnitude as the load cell observations. The anti-correlation pattern was shown to depend on the bed/surface slope. On a flat bed with laterally constrained cross-section, the resulting bridging effect diverted some of the normal forces acting on the bed to the sides. The anti-correlated pressure variations were then reproduced at a distance >10–20 m from the channel. In contrast, when the bed was inclined, the channel support of the overlying ice was vertical only, causing a reduction of the normal stress on the bed. With a bed slope of 5 degrees, the anti-correlation occurred within 10 m of the channel. The model thus showed that the effect of stress redistribution can lead to an opposite response in pressure at the same distance from the channel and that anti-correlation in pressure is reproduced without invoking cavity expansion caused by sliding. Article in Journal/Newspaper glacier Northern Norway Svartisen Directory of Open Access Journals: DOAJ Articles Norway Svartisen ENVELOPE(13.698,13.698,66.642,66.642) Engabreen ENVELOPE(13.771,13.771,66.682,66.682) Frontiers in Earth Science 5 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
subglacial processes glacier hydrology glacier mechanics glacier modelling Svartisen Subglacial Laboratory Engabreen Science Q |
spellingShingle |
subglacial processes glacier hydrology glacier mechanics glacier modelling Svartisen Subglacial Laboratory Engabreen Science Q Pierre-Marie Lefeuvre Thomas Zwinger Miriam Jackson Olivier Gagliardini Gaute Lappegard Jon Ove Hagen Stress Redistribution Explains Anti-correlated Subglacial Pressure Variations |
topic_facet |
subglacial processes glacier hydrology glacier mechanics glacier modelling Svartisen Subglacial Laboratory Engabreen Science Q |
description |
We used a finite element model to interpret anti-correlated pressure variations at the base of a glacier to demonstrate the importance of stress redistribution in the basal ice. We first investigated two pairs of load cells installed 20 m apart at the base of the 210 m thick Engabreen glacier in Northern Norway. The load cell data for July 2003 showed that pressurisation of a subglacial channel located over one load cell pair led to anti-correlation in pressure between the two pairs. To investigate the cause of this anti-correlation, we used a full Stokes 3D model of a 210 m thick and 25–200 m wide glacier with a pressurised subglacial channel represented as a pressure boundary condition. The model reproduced the anti-correlated pressure response at the glacier bed and variations in pressure of the same order of magnitude as the load cell observations. The anti-correlation pattern was shown to depend on the bed/surface slope. On a flat bed with laterally constrained cross-section, the resulting bridging effect diverted some of the normal forces acting on the bed to the sides. The anti-correlated pressure variations were then reproduced at a distance >10–20 m from the channel. In contrast, when the bed was inclined, the channel support of the overlying ice was vertical only, causing a reduction of the normal stress on the bed. With a bed slope of 5 degrees, the anti-correlation occurred within 10 m of the channel. The model thus showed that the effect of stress redistribution can lead to an opposite response in pressure at the same distance from the channel and that anti-correlation in pressure is reproduced without invoking cavity expansion caused by sliding. |
format |
Article in Journal/Newspaper |
author |
Pierre-Marie Lefeuvre Thomas Zwinger Miriam Jackson Olivier Gagliardini Gaute Lappegard Jon Ove Hagen |
author_facet |
Pierre-Marie Lefeuvre Thomas Zwinger Miriam Jackson Olivier Gagliardini Gaute Lappegard Jon Ove Hagen |
author_sort |
Pierre-Marie Lefeuvre |
title |
Stress Redistribution Explains Anti-correlated Subglacial Pressure Variations |
title_short |
Stress Redistribution Explains Anti-correlated Subglacial Pressure Variations |
title_full |
Stress Redistribution Explains Anti-correlated Subglacial Pressure Variations |
title_fullStr |
Stress Redistribution Explains Anti-correlated Subglacial Pressure Variations |
title_full_unstemmed |
Stress Redistribution Explains Anti-correlated Subglacial Pressure Variations |
title_sort |
stress redistribution explains anti-correlated subglacial pressure variations |
publisher |
Frontiers Media S.A. |
publishDate |
2018 |
url |
https://doi.org/10.3389/feart.2017.00110 https://doaj.org/article/31b869e40e274d8fbd3df5cda6f36e93 |
long_lat |
ENVELOPE(13.698,13.698,66.642,66.642) ENVELOPE(13.771,13.771,66.682,66.682) |
geographic |
Norway Svartisen Engabreen |
geographic_facet |
Norway Svartisen Engabreen |
genre |
glacier Northern Norway Svartisen |
genre_facet |
glacier Northern Norway Svartisen |
op_source |
Frontiers in Earth Science, Vol 5 (2018) |
op_relation |
http://journal.frontiersin.org/article/10.3389/feart.2017.00110/full https://doaj.org/toc/2296-6463 2296-6463 doi:10.3389/feart.2017.00110 https://doaj.org/article/31b869e40e274d8fbd3df5cda6f36e93 |
op_doi |
https://doi.org/10.3389/feart.2017.00110 |
container_title |
Frontiers in Earth Science |
container_volume |
5 |
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1766009904355606528 |