Relating the occurrence of crevasses to surface strain rates
The presence of crevasses on the surface of ice masses indicates that a fracture criterion has been met. Understanding how crevasses form will provide information about the stress and strain-rate fields in the ice. This study derives a relationship between measurements of strain rate and observation...
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International Glaciological Society
1993
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Online Access: | http://nora.nerc.ac.uk/id/eprint/518108/ https://doi.org/10.3189/S0022143000015926 |
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ftnerc:oai:nora.nerc.ac.uk:518108 2023-05-15T13:49:34+02:00 Relating the occurrence of crevasses to surface strain rates Vaughan, David G. 1993 http://nora.nerc.ac.uk/id/eprint/518108/ https://doi.org/10.3189/S0022143000015926 unknown International Glaciological Society Vaughan, David G. orcid:0000-0002-9065-0570 . 1993 Relating the occurrence of crevasses to surface strain rates. Journal of Glaciology, 39 (132). 255-266. https://doi.org/10.3189/S0022143000015926 <https://doi.org/10.3189/S0022143000015926> Publication - Article PeerReviewed 1993 ftnerc https://doi.org/10.3189/S0022143000015926 2023-02-04T19:45:31Z The presence of crevasses on the surface of ice masses indicates that a fracture criterion has been met. Understanding how crevasses form will provide information about the stress and strain-rate fields in the ice. This study derives a relationship between measurements of strain rate and observations of crevassing on the surface of ice masses. A literature search yielded 17 polar and alpine locations where strain rates had been measured and crevassing recorded. By plotting strain rates (converted to stresses using a creep law) using axes representing the surface-parallel principal stresses, failure envelopes were derived by enclosing measurements where surface crevassing was absent. The derived failure envelopes were found to conform well to theoretical ones predicted by the Coulomb and the maximum octahedral shear stress (von Mises) theories of failure. The derived failure envelopes were scaled by the tensile strength, which was found to vary from 90 to 320 kPa. There was no systematic variation of tensile strength with either temperature at 10 m depth or the method used to locate the crevasses. The observed variation in tensile strength could result from variations in ice properties (e.g. crystal size, impurity content or density) or could be related to uncertainty in the constitutive relation. Creep flow and fracture share a very similar temperature dependence, suggesting similar crystal-scale processes are responsible for both. The observed relationship will provide a supplementary tool with which to verify and test models of ice dynamics against remotely sensed imagery. The study also indicates that a temperature rise of a few degrees throughout the ice column will not result directly in any increase in calving rates from the large Antarctic ice shelves such as the Filchner–Ronne or Ross Ice Shelves. Article in Journal/Newspaper Antarc* Antarctic Ice Shelves Journal of Glaciology Natural Environment Research Council: NERC Open Research Archive Antarctic Journal of Glaciology 39 132 255 266 |
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Natural Environment Research Council: NERC Open Research Archive |
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The presence of crevasses on the surface of ice masses indicates that a fracture criterion has been met. Understanding how crevasses form will provide information about the stress and strain-rate fields in the ice. This study derives a relationship between measurements of strain rate and observations of crevassing on the surface of ice masses. A literature search yielded 17 polar and alpine locations where strain rates had been measured and crevassing recorded. By plotting strain rates (converted to stresses using a creep law) using axes representing the surface-parallel principal stresses, failure envelopes were derived by enclosing measurements where surface crevassing was absent. The derived failure envelopes were found to conform well to theoretical ones predicted by the Coulomb and the maximum octahedral shear stress (von Mises) theories of failure. The derived failure envelopes were scaled by the tensile strength, which was found to vary from 90 to 320 kPa. There was no systematic variation of tensile strength with either temperature at 10 m depth or the method used to locate the crevasses. The observed variation in tensile strength could result from variations in ice properties (e.g. crystal size, impurity content or density) or could be related to uncertainty in the constitutive relation. Creep flow and fracture share a very similar temperature dependence, suggesting similar crystal-scale processes are responsible for both. The observed relationship will provide a supplementary tool with which to verify and test models of ice dynamics against remotely sensed imagery. The study also indicates that a temperature rise of a few degrees throughout the ice column will not result directly in any increase in calving rates from the large Antarctic ice shelves such as the Filchner–Ronne or Ross Ice Shelves. |
format |
Article in Journal/Newspaper |
author |
Vaughan, David G. |
spellingShingle |
Vaughan, David G. Relating the occurrence of crevasses to surface strain rates |
author_facet |
Vaughan, David G. |
author_sort |
Vaughan, David G. |
title |
Relating the occurrence of crevasses to surface strain rates |
title_short |
Relating the occurrence of crevasses to surface strain rates |
title_full |
Relating the occurrence of crevasses to surface strain rates |
title_fullStr |
Relating the occurrence of crevasses to surface strain rates |
title_full_unstemmed |
Relating the occurrence of crevasses to surface strain rates |
title_sort |
relating the occurrence of crevasses to surface strain rates |
publisher |
International Glaciological Society |
publishDate |
1993 |
url |
http://nora.nerc.ac.uk/id/eprint/518108/ https://doi.org/10.3189/S0022143000015926 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Ice Shelves Journal of Glaciology |
genre_facet |
Antarc* Antarctic Ice Shelves Journal of Glaciology |
op_relation |
Vaughan, David G. orcid:0000-0002-9065-0570 . 1993 Relating the occurrence of crevasses to surface strain rates. Journal of Glaciology, 39 (132). 255-266. https://doi.org/10.3189/S0022143000015926 <https://doi.org/10.3189/S0022143000015926> |
op_doi |
https://doi.org/10.3189/S0022143000015926 |
container_title |
Journal of Glaciology |
container_volume |
39 |
container_issue |
132 |
container_start_page |
255 |
op_container_end_page |
266 |
_version_ |
1766251707840331776 |