Grounding zone subglacial properties from calibrated active-source seismic methods
The grounding zone of Whillans Ice Stream, West Antarctica, exhibits an abrupt transition in basal properties from the grounded ice to the ocean cavity over distances of less than 0.5–1 km. Active-source seismic methods reveal the downglacier-most grounded portion of the ice stream is underlain by a...
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Copernicus Publications
2021
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00056292 2024-09-15T17:47:37+00:00 Grounding zone subglacial properties from calibrated active-source seismic methods Horgan, Huw J. van Haastrecht, Laurine Alley, Richard B. Anandakrishnan, Sridhar Beem, Lucas H. Christianson, Knut Muto, Atsuhiro Siegfried, Matthew R. 2021-04 electronic https://doi.org/10.5194/tc-15-1863-2021 https://noa.gwlb.de/receive/cop_mods_00056292 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00055943/tc-15-1863-2021.pdf https://tc.copernicus.org/articles/15/1863/2021/tc-15-1863-2021.pdf eng eng Copernicus Publications The Cryosphere -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-15-1863-2021 https://noa.gwlb.de/receive/cop_mods_00056292 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00055943/tc-15-1863-2021.pdf https://tc.copernicus.org/articles/15/1863/2021/tc-15-1863-2021.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2021 ftnonlinearchiv https://doi.org/10.5194/tc-15-1863-2021 2024-06-26T04:40:00Z The grounding zone of Whillans Ice Stream, West Antarctica, exhibits an abrupt transition in basal properties from the grounded ice to the ocean cavity over distances of less than 0.5–1 km. Active-source seismic methods reveal the downglacier-most grounded portion of the ice stream is underlain by a relatively stiff substrate (relatively high shear wave velocities of 1100±430 m s−1) compared to the deformable till found elsewhere beneath the ice stream. Changes in basal reflectivity in our study area cannot be explained by the stage of the tide. Several kilometres upstream of the grounding zone, layers of subglacial water are detected, as are regions that appear to be water layers but are less than the thickness resolvable by our technique. The presence of stiff subglacial sediment and thin water layers upstream of the grounding zone supports previous studies that have proposed the dewatering of sediment within the grounding zone and the trapping of subglacial water upstream of the ocean cavity. The setting enables calibration of our methodology using returns from the floating ice shelf. This allows a comparison of different techniques used to estimate the sizes of the seismic sources, a constraint essential for the accurate recovery of subglacial properties. We find a strong correlation (coefficient of determination=0.46) between our calibrated method and a commonly used multiple-bounce method, but our results also highlight the incomplete knowledge of other factors affecting the amplitude of seismic sources and reflections in the cryosphere. Article in Journal/Newspaper Antarc* Antarctica Ice Shelf The Cryosphere West Antarctica Whillans Ice Stream Niedersächsisches Online-Archiv NOA The Cryosphere 15 4 1863 1880 |
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Niedersächsisches Online-Archiv NOA |
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English |
topic |
article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Horgan, Huw J. van Haastrecht, Laurine Alley, Richard B. Anandakrishnan, Sridhar Beem, Lucas H. Christianson, Knut Muto, Atsuhiro Siegfried, Matthew R. Grounding zone subglacial properties from calibrated active-source seismic methods |
topic_facet |
article Verlagsveröffentlichung |
description |
The grounding zone of Whillans Ice Stream, West Antarctica, exhibits an abrupt transition in basal properties from the grounded ice to the ocean cavity over distances of less than 0.5–1 km. Active-source seismic methods reveal the downglacier-most grounded portion of the ice stream is underlain by a relatively stiff substrate (relatively high shear wave velocities of 1100±430 m s−1) compared to the deformable till found elsewhere beneath the ice stream. Changes in basal reflectivity in our study area cannot be explained by the stage of the tide. Several kilometres upstream of the grounding zone, layers of subglacial water are detected, as are regions that appear to be water layers but are less than the thickness resolvable by our technique. The presence of stiff subglacial sediment and thin water layers upstream of the grounding zone supports previous studies that have proposed the dewatering of sediment within the grounding zone and the trapping of subglacial water upstream of the ocean cavity. The setting enables calibration of our methodology using returns from the floating ice shelf. This allows a comparison of different techniques used to estimate the sizes of the seismic sources, a constraint essential for the accurate recovery of subglacial properties. We find a strong correlation (coefficient of determination=0.46) between our calibrated method and a commonly used multiple-bounce method, but our results also highlight the incomplete knowledge of other factors affecting the amplitude of seismic sources and reflections in the cryosphere. |
format |
Article in Journal/Newspaper |
author |
Horgan, Huw J. van Haastrecht, Laurine Alley, Richard B. Anandakrishnan, Sridhar Beem, Lucas H. Christianson, Knut Muto, Atsuhiro Siegfried, Matthew R. |
author_facet |
Horgan, Huw J. van Haastrecht, Laurine Alley, Richard B. Anandakrishnan, Sridhar Beem, Lucas H. Christianson, Knut Muto, Atsuhiro Siegfried, Matthew R. |
author_sort |
Horgan, Huw J. |
title |
Grounding zone subglacial properties from calibrated active-source seismic methods |
title_short |
Grounding zone subglacial properties from calibrated active-source seismic methods |
title_full |
Grounding zone subglacial properties from calibrated active-source seismic methods |
title_fullStr |
Grounding zone subglacial properties from calibrated active-source seismic methods |
title_full_unstemmed |
Grounding zone subglacial properties from calibrated active-source seismic methods |
title_sort |
grounding zone subglacial properties from calibrated active-source seismic methods |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-15-1863-2021 https://noa.gwlb.de/receive/cop_mods_00056292 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00055943/tc-15-1863-2021.pdf https://tc.copernicus.org/articles/15/1863/2021/tc-15-1863-2021.pdf |
genre |
Antarc* Antarctica Ice Shelf The Cryosphere West Antarctica Whillans Ice Stream |
genre_facet |
Antarc* Antarctica Ice Shelf The Cryosphere West Antarctica Whillans Ice Stream |
op_relation |
The Cryosphere -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-15-1863-2021 https://noa.gwlb.de/receive/cop_mods_00056292 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00055943/tc-15-1863-2021.pdf https://tc.copernicus.org/articles/15/1863/2021/tc-15-1863-2021.pdf |
op_rights |
https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/tc-15-1863-2021 |
container_title |
The Cryosphere |
container_volume |
15 |
container_issue |
4 |
container_start_page |
1863 |
op_container_end_page |
1880 |
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1810497077907554304 |