C33A-0765: Subglacial processes recorded by in situ wireless probes: stick-slip motion and till deposition
C33A-0765: Subglacial processes recorded by in situ wireless probes: stick-slip motion and till deposition
We investigate the subglacial behaviour of a glacier resting on a deformable bed with a ‘fast’ transfer rate through the ice, using the unique Glacsweb wireless in situ probes, embedded in both the ice and till. This glacier responds immediately to changes in surface meltwater inputs, with a secondary slower englacial pathway with a five lag. In summer the subglacial hydrology is in semi-equilibrium and most meltwater fluctuations are absorbed by the system. However, whenever meltwater inputs exceed the subglacial hydrological systems ability to cope (a few days in summer, but all the time in winter) a distinct pattern of stick-slip motion occurs. Melt events cause basal sliding, leading to antithetic (backwards) tilt, water pressure decreases and dilatant strengthening, followed by a slow water pressure rise and strain softening, until the next cycle begins. We show the bed is a patchwork of different strengths, indicate their scale and describe any temporal changes. We reveal the behaviour of the till, showing that deformation occurs all year, with a combination of lodging and till flowing around obstacles, stable ‘islands’ of high pressures with constant depositional processes, and variable water pressures leading to a more complex sedimentary patterns. These processes combine together to produce a deformation till.
Hart, Jane
e949a885-7b26-4544-9e15-32ba6f87e49a
December 2016
Hart, Jane
e949a885-7b26-4544-9e15-32ba6f87e49a
Hart, Jane
(2016)
C33A-0765: Subglacial processes recorded by in situ wireless probes: stick-slip motion and till deposition.
American Geophysical Union, Fall Meeting 2016, , San Francisco, United States.
12 - 16 Dec 2016.
Record type:
Conference or Workshop Item
(Other)
Abstract
We investigate the subglacial behaviour of a glacier resting on a deformable bed with a ‘fast’ transfer rate through the ice, using the unique Glacsweb wireless in situ probes, embedded in both the ice and till. This glacier responds immediately to changes in surface meltwater inputs, with a secondary slower englacial pathway with a five lag. In summer the subglacial hydrology is in semi-equilibrium and most meltwater fluctuations are absorbed by the system. However, whenever meltwater inputs exceed the subglacial hydrological systems ability to cope (a few days in summer, but all the time in winter) a distinct pattern of stick-slip motion occurs. Melt events cause basal sliding, leading to antithetic (backwards) tilt, water pressure decreases and dilatant strengthening, followed by a slow water pressure rise and strain softening, until the next cycle begins. We show the bed is a patchwork of different strengths, indicate their scale and describe any temporal changes. We reveal the behaviour of the till, showing that deformation occurs all year, with a combination of lodging and till flowing around obstacles, stable ‘islands’ of high pressures with constant depositional processes, and variable water pressures leading to a more complex sedimentary patterns. These processes combine together to produce a deformation till.
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Published date: December 2016
Venue - Dates:
American Geophysical Union, Fall Meeting 2016, , San Francisco, United States, 2016-12-12 - 2016-12-16
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Local EPrints ID: 432533
URI: http://eprints.soton.ac.uk/id/eprint/432533
PURE UUID: 57e7498a-e8ac-4d32-abf0-8302d62071f1
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Date deposited: 17 Jul 2019 16:30
Last modified: 23 Feb 2023 02:34
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