Seismic-reflection evidence for a deep subglacial trough beneath Jakobshavns Isbræ, West Greenland
Abstract Seismic-reflection methods were used to determine the ice thickness and basal topography of Jakobshavns Isbræ, a large, fast-moving ice stream/outlet glacier in West Greenland. A method of data analysis was developed which involves the pointwise migration of data from a linear seismic array...
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Cambridge University Press (CUP)
1996
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Online Access: | http://dx.doi.org/10.1017/s0022143000004081 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000004081 |
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crcambridgeupr:10.1017/s0022143000004081 2024-09-15T18:07:45+00:00 Seismic-reflection evidence for a deep subglacial trough beneath Jakobshavns Isbræ, West Greenland Clarke, Ted S. Echelmeyer, Keiih 1996 http://dx.doi.org/10.1017/s0022143000004081 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000004081 en eng Cambridge University Press (CUP) Journal of Glaciology volume 42, issue 141, page 219-232 ISSN 0022-1430 1727-5652 journal-article 1996 crcambridgeupr https://doi.org/10.1017/s0022143000004081 2024-07-10T04:04:32Z Abstract Seismic-reflection methods were used to determine the ice thickness and basal topography of Jakobshavns Isbræ, a large, fast-moving ice stream/outlet glacier in West Greenland. A method of data analysis was developed which involves the pointwise migration of data from a linear seismic array and a single explosive source; the method yields the depth, horizontal position and slope of the basal reflector. A deep U-shaped subglacial trough was found beneath the entire length of the well-defined ice stream. The trough is incised up to 1500 m into bedrock, and its base lies 1200–1500 m below sea level for at least 70 km inland. Center-line ice thickness along most of the channel is about 2500 m, or about 2.5 times that of the surrounding ice sheet. This prominent bedrock trough was not apparent in existing radio-echo-sounding data. Reflection coefficients indicate that much of the basal interface is probably underlain by compacted, non-deforming sediment. The large ice thickness, coupled with relatively steep surface slopes, leads to high basal shear stresses (200–300 k Pa) along the ice stream. The large shear stresses and lack of a deformable bed imply that internal deformation plays a dominant role in the dynamics of Jakobshavns Isbræ. Article in Journal/Newspaper glacier Greenland Ice Sheet Journal of Glaciology Cambridge University Press Journal of Glaciology 42 141 219 232 |
institution |
Open Polar |
collection |
Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Abstract Seismic-reflection methods were used to determine the ice thickness and basal topography of Jakobshavns Isbræ, a large, fast-moving ice stream/outlet glacier in West Greenland. A method of data analysis was developed which involves the pointwise migration of data from a linear seismic array and a single explosive source; the method yields the depth, horizontal position and slope of the basal reflector. A deep U-shaped subglacial trough was found beneath the entire length of the well-defined ice stream. The trough is incised up to 1500 m into bedrock, and its base lies 1200–1500 m below sea level for at least 70 km inland. Center-line ice thickness along most of the channel is about 2500 m, or about 2.5 times that of the surrounding ice sheet. This prominent bedrock trough was not apparent in existing radio-echo-sounding data. Reflection coefficients indicate that much of the basal interface is probably underlain by compacted, non-deforming sediment. The large ice thickness, coupled with relatively steep surface slopes, leads to high basal shear stresses (200–300 k Pa) along the ice stream. The large shear stresses and lack of a deformable bed imply that internal deformation plays a dominant role in the dynamics of Jakobshavns Isbræ. |
format |
Article in Journal/Newspaper |
author |
Clarke, Ted S. Echelmeyer, Keiih |
spellingShingle |
Clarke, Ted S. Echelmeyer, Keiih Seismic-reflection evidence for a deep subglacial trough beneath Jakobshavns Isbræ, West Greenland |
author_facet |
Clarke, Ted S. Echelmeyer, Keiih |
author_sort |
Clarke, Ted S. |
title |
Seismic-reflection evidence for a deep subglacial trough beneath Jakobshavns Isbræ, West Greenland |
title_short |
Seismic-reflection evidence for a deep subglacial trough beneath Jakobshavns Isbræ, West Greenland |
title_full |
Seismic-reflection evidence for a deep subglacial trough beneath Jakobshavns Isbræ, West Greenland |
title_fullStr |
Seismic-reflection evidence for a deep subglacial trough beneath Jakobshavns Isbræ, West Greenland |
title_full_unstemmed |
Seismic-reflection evidence for a deep subglacial trough beneath Jakobshavns Isbræ, West Greenland |
title_sort |
seismic-reflection evidence for a deep subglacial trough beneath jakobshavns isbræ, west greenland |
publisher |
Cambridge University Press (CUP) |
publishDate |
1996 |
url |
http://dx.doi.org/10.1017/s0022143000004081 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000004081 |
genre |
glacier Greenland Ice Sheet Journal of Glaciology |
genre_facet |
glacier Greenland Ice Sheet Journal of Glaciology |
op_source |
Journal of Glaciology volume 42, issue 141, page 219-232 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000004081 |
container_title |
Journal of Glaciology |
container_volume |
42 |
container_issue |
141 |
container_start_page |
219 |
op_container_end_page |
232 |
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1810445128647573504 |