Bending Shear: The Rate-Controlling Mechanism for Calving Ice Walls
Bending shear was observed to produce nearly vertical shear bands in a calving ice wall standing on dry land on Deception Island (Iat. 63.0 oS., long. 60.6 W.), and slabs calved straight downward when shear rupture occurred along these shear bands (Hughes, 1989). A formula for the calving rate was d...
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ftmaineuniv:oai:digitalcommons.library.umaine.edu:ers_facpub-1015 2023-05-15T16:00:28+02:00 Bending Shear: The Rate-Controlling Mechanism for Calving Ice Walls Hughes, Terence J. Nakagawa, Masayuki 1989-01-01T08:00:00Z application/pdf https://digitalcommons.library.umaine.edu/ers_facpub/16 https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=1015&context=ers_facpub unknown DigitalCommons@UMaine https://digitalcommons.library.umaine.edu/ers_facpub/16 https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=1015&context=ers_facpub This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. In addition, no permission is required from the rights-holder(s) for educational uses. For other uses, you need to obtain permission from the rights-holder(s). Earth Science Faculty Scholarship Earth Sciences text 1989 ftmaineuniv 2023-03-12T18:49:23Z Bending shear was observed to produce nearly vertical shear bands in a calving ice wall standing on dry land on Deception Island (Iat. 63.0 oS., long. 60.6 W.), and slabs calved straight downward when shear rupture occurred along these shear bands (Hughes, 1989). A formula for the calving rate was developed from the Deception Island data, and we have attempted to justify generalizing this formula to include ice walls standing along beaches or in water. These are environments in which a wave-washed groove develops along the base of the ice wall or along a water line above the base. The rate of wave erosion provides an alternative mechanism for controlling the calving rate in these environments. We have determined that the rate at which bending creep produces nearly vertical shear bands, along which shear r upture occurs, controls the calving rate in all environments. Shear rupture occurs at a calving shear stress of about I bar. Our results justify using the calving formula to compute the calving rate of ice walls in computer models of ice-sheet dynamics. This is especially important in simulating retreat of Northern Hemisphere ice sheets during the last deglaciation, when marine and lacustrine environments were common along retreating ice margins. These margins would have been ice walls standing along beaches or in water, because floating ice shelves are not expected in the ablation zone of retreating ice sheets. Text Deception Island Ice Sheet Ice Shelves The University of Maine: DigitalCommons@UMaine Deception Island ENVELOPE(-60.633,-60.633,-62.950,-62.950) |
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Open Polar |
collection |
The University of Maine: DigitalCommons@UMaine |
op_collection_id |
ftmaineuniv |
language |
unknown |
topic |
Earth Sciences |
spellingShingle |
Earth Sciences Hughes, Terence J. Nakagawa, Masayuki Bending Shear: The Rate-Controlling Mechanism for Calving Ice Walls |
topic_facet |
Earth Sciences |
description |
Bending shear was observed to produce nearly vertical shear bands in a calving ice wall standing on dry land on Deception Island (Iat. 63.0 oS., long. 60.6 W.), and slabs calved straight downward when shear rupture occurred along these shear bands (Hughes, 1989). A formula for the calving rate was developed from the Deception Island data, and we have attempted to justify generalizing this formula to include ice walls standing along beaches or in water. These are environments in which a wave-washed groove develops along the base of the ice wall or along a water line above the base. The rate of wave erosion provides an alternative mechanism for controlling the calving rate in these environments. We have determined that the rate at which bending creep produces nearly vertical shear bands, along which shear r upture occurs, controls the calving rate in all environments. Shear rupture occurs at a calving shear stress of about I bar. Our results justify using the calving formula to compute the calving rate of ice walls in computer models of ice-sheet dynamics. This is especially important in simulating retreat of Northern Hemisphere ice sheets during the last deglaciation, when marine and lacustrine environments were common along retreating ice margins. These margins would have been ice walls standing along beaches or in water, because floating ice shelves are not expected in the ablation zone of retreating ice sheets. |
format |
Text |
author |
Hughes, Terence J. Nakagawa, Masayuki |
author_facet |
Hughes, Terence J. Nakagawa, Masayuki |
author_sort |
Hughes, Terence J. |
title |
Bending Shear: The Rate-Controlling Mechanism for Calving Ice Walls |
title_short |
Bending Shear: The Rate-Controlling Mechanism for Calving Ice Walls |
title_full |
Bending Shear: The Rate-Controlling Mechanism for Calving Ice Walls |
title_fullStr |
Bending Shear: The Rate-Controlling Mechanism for Calving Ice Walls |
title_full_unstemmed |
Bending Shear: The Rate-Controlling Mechanism for Calving Ice Walls |
title_sort |
bending shear: the rate-controlling mechanism for calving ice walls |
publisher |
DigitalCommons@UMaine |
publishDate |
1989 |
url |
https://digitalcommons.library.umaine.edu/ers_facpub/16 https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=1015&context=ers_facpub |
long_lat |
ENVELOPE(-60.633,-60.633,-62.950,-62.950) |
geographic |
Deception Island |
geographic_facet |
Deception Island |
genre |
Deception Island Ice Sheet Ice Shelves |
genre_facet |
Deception Island Ice Sheet Ice Shelves |
op_source |
Earth Science Faculty Scholarship |
op_relation |
https://digitalcommons.library.umaine.edu/ers_facpub/16 https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=1015&context=ers_facpub |
op_rights |
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. In addition, no permission is required from the rights-holder(s) for educational uses. For other uses, you need to obtain permission from the rights-holder(s). |
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1766396447999131648 |