Glacier Surge Mechanism Based on Linked Cavity Configuration of the Basal Water Conduit System
Based on observations of the 1982–1983 surge of Variegated Glacier, Alaska, a model of the surge mechanism is developed in terms of a transition from the normal tunnel configuration of the basal water conduit system to a linked cavity configuration that tends to restrict the flow of water, resulti...
Published in: | Journal of Geophysical Research: Solid Earth |
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American Geophysical Union
1987
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Online Access: | https://doi.org/10.1029/JB092iB09p09083 |
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ftcaltechauth:oai:authors.library.caltech.edu:xeaqw-0es87 2024-09-15T18:07:34+00:00 Glacier Surge Mechanism Based on Linked Cavity Configuration of the Basal Water Conduit System Kamb, Barclay 1987-08-10 https://doi.org/10.1029/JB092iB09p09083 unknown American Geophysical Union https://doi.org/10.1029/JB092iB09p09083 oai:authors.library.caltech.edu:xeaqw-0es87 eprintid:49956 resolverid:CaltechAUTHORS:20140923-143045627 info:eu-repo/semantics/openAccess Other Journal of Geophysical Research B, 92(B9), 9083-9100, (1987-08-10) info:eu-repo/semantics/article 1987 ftcaltechauth https://doi.org/10.1029/JB092iB09p09083 2024-08-06T15:34:58Z Based on observations of the 1982–1983 surge of Variegated Glacier, Alaska, a model of the surge mechanism is developed in terms of a transition from the normal tunnel configuration of the basal water conduit system to a linked cavity configuration that tends to restrict the flow of water, resulting in increased basal water pressures that cause rapid basal sliding. The linked cavity system consists of basal cavities formed by ice-bedrock separation (cavitation), ∼1 m high and ∼10 m in horizontal dimensions, widely scattered over the glacier bed, and hydraulically linked by narrow connections where separation is minimal (separation gap ≲ 0.1 m). The narrow connections, called orifices, control the water flow through the conduit system; by throttling the flow through the large cavities, the orifices keep the water flux transmitted by the basal water system at normal levels even though the total cavity cross-sectional area (∼200 m^2) is much larger than that of a tunnel system (∼10 m^2). A physical model of the linked cavity system is formulated in terms of the dimensions of the "typical" cavity and orifice and the numbers of these across the glacier width. The model concentrates on the detailed configuration of the typical orifice and its response to basal water pressure and basal sliding, which determines the water flux carried by the system under given conditions. Configurations are worked out for two idealized orifice types, step orifices that form in the lee of downglacier-facing bedrock steps, and wave orifices that form on the lee slopes of quasisinusoidal bedrock waves and are similar to transverse "N channels." The orifice configurations are obtained from the results of solutions of the basal-sliding-with-separation problem for an ice mass constituting of linear half-space of linear rheology, with nonlinearity introduced by making the viscosity stress-dependent on an intuitive basis. Modification of the orifice shapes by melting of the ice roof due to viscous heat dissipation in the flow of ... Article in Journal/Newspaper glacier Alaska Caltech Authors (California Institute of Technology) Journal of Geophysical Research: Solid Earth 92 B9 9083 9100 |
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Caltech Authors (California Institute of Technology) |
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unknown |
description |
Based on observations of the 1982–1983 surge of Variegated Glacier, Alaska, a model of the surge mechanism is developed in terms of a transition from the normal tunnel configuration of the basal water conduit system to a linked cavity configuration that tends to restrict the flow of water, resulting in increased basal water pressures that cause rapid basal sliding. The linked cavity system consists of basal cavities formed by ice-bedrock separation (cavitation), ∼1 m high and ∼10 m in horizontal dimensions, widely scattered over the glacier bed, and hydraulically linked by narrow connections where separation is minimal (separation gap ≲ 0.1 m). The narrow connections, called orifices, control the water flow through the conduit system; by throttling the flow through the large cavities, the orifices keep the water flux transmitted by the basal water system at normal levels even though the total cavity cross-sectional area (∼200 m^2) is much larger than that of a tunnel system (∼10 m^2). A physical model of the linked cavity system is formulated in terms of the dimensions of the "typical" cavity and orifice and the numbers of these across the glacier width. The model concentrates on the detailed configuration of the typical orifice and its response to basal water pressure and basal sliding, which determines the water flux carried by the system under given conditions. Configurations are worked out for two idealized orifice types, step orifices that form in the lee of downglacier-facing bedrock steps, and wave orifices that form on the lee slopes of quasisinusoidal bedrock waves and are similar to transverse "N channels." The orifice configurations are obtained from the results of solutions of the basal-sliding-with-separation problem for an ice mass constituting of linear half-space of linear rheology, with nonlinearity introduced by making the viscosity stress-dependent on an intuitive basis. Modification of the orifice shapes by melting of the ice roof due to viscous heat dissipation in the flow of ... |
format |
Article in Journal/Newspaper |
author |
Kamb, Barclay |
spellingShingle |
Kamb, Barclay Glacier Surge Mechanism Based on Linked Cavity Configuration of the Basal Water Conduit System |
author_facet |
Kamb, Barclay |
author_sort |
Kamb, Barclay |
title |
Glacier Surge Mechanism Based on Linked Cavity Configuration of the Basal Water Conduit System |
title_short |
Glacier Surge Mechanism Based on Linked Cavity Configuration of the Basal Water Conduit System |
title_full |
Glacier Surge Mechanism Based on Linked Cavity Configuration of the Basal Water Conduit System |
title_fullStr |
Glacier Surge Mechanism Based on Linked Cavity Configuration of the Basal Water Conduit System |
title_full_unstemmed |
Glacier Surge Mechanism Based on Linked Cavity Configuration of the Basal Water Conduit System |
title_sort |
glacier surge mechanism based on linked cavity configuration of the basal water conduit system |
publisher |
American Geophysical Union |
publishDate |
1987 |
url |
https://doi.org/10.1029/JB092iB09p09083 |
genre |
glacier Alaska |
genre_facet |
glacier Alaska |
op_source |
Journal of Geophysical Research B, 92(B9), 9083-9100, (1987-08-10) |
op_relation |
https://doi.org/10.1029/JB092iB09p09083 oai:authors.library.caltech.edu:xeaqw-0es87 eprintid:49956 resolverid:CaltechAUTHORS:20140923-143045627 |
op_rights |
info:eu-repo/semantics/openAccess Other |
op_doi |
https://doi.org/10.1029/JB092iB09p09083 |
container_title |
Journal of Geophysical Research: Solid Earth |
container_volume |
92 |
container_issue |
B9 |
container_start_page |
9083 |
op_container_end_page |
9100 |
_version_ |
1810444954662600704 |