Tidal Modulation of Ice Streams: Effect of Periodic Sliding Velocity on Ice Friction and Healing
Basal slip along glaciers and ice streams can be significantly modified by external time-dependent forcing, although it is not clear why some systems are more sensitive to tidal stresses. We have conducted a series of laboratory experiments to explore the effect of time varying load point velocity o...
Published in: | Frontiers in Earth Science |
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Online Access: | http://dx.doi.org/10.3389/feart.2022.719074 https://www.frontiersin.org/articles/10.3389/feart.2022.719074/full |
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crfrontiers:10.3389/feart.2022.719074 2024-05-19T07:32:13+00:00 Tidal Modulation of Ice Streams: Effect of Periodic Sliding Velocity on Ice Friction and Healing McCarthy, Christine Skarbek, Rob M. Savage, Heather M. 2022 http://dx.doi.org/10.3389/feart.2022.719074 https://www.frontiersin.org/articles/10.3389/feart.2022.719074/full unknown Frontiers Media SA https://creativecommons.org/licenses/by/4.0/ Frontiers in Earth Science volume 10 ISSN 2296-6463 journal-article 2022 crfrontiers https://doi.org/10.3389/feart.2022.719074 2024-05-01T06:49:16Z Basal slip along glaciers and ice streams can be significantly modified by external time-dependent forcing, although it is not clear why some systems are more sensitive to tidal stresses. We have conducted a series of laboratory experiments to explore the effect of time varying load point velocity on ice-on-rock friction. Varying the load point velocity induces shear stress forcing, making this an analogous simulation of aspects of ice stream tidal modulation. Ambient pressure, double-direct shear experiments were conducted in a cryogenic servo-controlled biaxial deformation apparatus at temperatures between −2°C and −16°C. In addition to a background, median velocity (1 and 10 μm/s), a sinusoidal velocity was applied to the central sliding sample over a range of periods and amplitudes. Normal stress was held constant over each run (0.1, 0.5 or 1 MPa) and the shear stress was measured. Over the range of parameters studied, the full spectrum of slip behavior from creeping to slow-slip to stick-slip was observed, similar to the diversity of sliding styles observed in Antarctic and Greenland ice streams. Under conditions in which the amplitude of oscillation is equal to the median velocity, significant healing occurs as velocity approaches zero, causing a high-amplitude change in friction. The amplitude of the event increases with increasing period (i.e. hold time). At high normal stress, velocity oscillations force an otherwise stable system to behave unstably, with consistently-timed events during every cycle. Rate-state friction parameters determined from velocity steps show that the ice-rock interface is velocity strengthening. A companion paper describes a method of analyzing the oscillatory data directly. Forward modeling of a sinusoidally-driven slider block, using rate-and-state dependent friction formulation and experimentally derived parameters, successfully predicts the experimental output in all but a few cases. Article in Journal/Newspaper Antarc* Antarctic Greenland Frontiers (Publisher) Frontiers in Earth Science 10 |
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Basal slip along glaciers and ice streams can be significantly modified by external time-dependent forcing, although it is not clear why some systems are more sensitive to tidal stresses. We have conducted a series of laboratory experiments to explore the effect of time varying load point velocity on ice-on-rock friction. Varying the load point velocity induces shear stress forcing, making this an analogous simulation of aspects of ice stream tidal modulation. Ambient pressure, double-direct shear experiments were conducted in a cryogenic servo-controlled biaxial deformation apparatus at temperatures between −2°C and −16°C. In addition to a background, median velocity (1 and 10 μm/s), a sinusoidal velocity was applied to the central sliding sample over a range of periods and amplitudes. Normal stress was held constant over each run (0.1, 0.5 or 1 MPa) and the shear stress was measured. Over the range of parameters studied, the full spectrum of slip behavior from creeping to slow-slip to stick-slip was observed, similar to the diversity of sliding styles observed in Antarctic and Greenland ice streams. Under conditions in which the amplitude of oscillation is equal to the median velocity, significant healing occurs as velocity approaches zero, causing a high-amplitude change in friction. The amplitude of the event increases with increasing period (i.e. hold time). At high normal stress, velocity oscillations force an otherwise stable system to behave unstably, with consistently-timed events during every cycle. Rate-state friction parameters determined from velocity steps show that the ice-rock interface is velocity strengthening. A companion paper describes a method of analyzing the oscillatory data directly. Forward modeling of a sinusoidally-driven slider block, using rate-and-state dependent friction formulation and experimentally derived parameters, successfully predicts the experimental output in all but a few cases. |
format |
Article in Journal/Newspaper |
author |
McCarthy, Christine Skarbek, Rob M. Savage, Heather M. |
spellingShingle |
McCarthy, Christine Skarbek, Rob M. Savage, Heather M. Tidal Modulation of Ice Streams: Effect of Periodic Sliding Velocity on Ice Friction and Healing |
author_facet |
McCarthy, Christine Skarbek, Rob M. Savage, Heather M. |
author_sort |
McCarthy, Christine |
title |
Tidal Modulation of Ice Streams: Effect of Periodic Sliding Velocity on Ice Friction and Healing |
title_short |
Tidal Modulation of Ice Streams: Effect of Periodic Sliding Velocity on Ice Friction and Healing |
title_full |
Tidal Modulation of Ice Streams: Effect of Periodic Sliding Velocity on Ice Friction and Healing |
title_fullStr |
Tidal Modulation of Ice Streams: Effect of Periodic Sliding Velocity on Ice Friction and Healing |
title_full_unstemmed |
Tidal Modulation of Ice Streams: Effect of Periodic Sliding Velocity on Ice Friction and Healing |
title_sort |
tidal modulation of ice streams: effect of periodic sliding velocity on ice friction and healing |
publisher |
Frontiers Media SA |
publishDate |
2022 |
url |
http://dx.doi.org/10.3389/feart.2022.719074 https://www.frontiersin.org/articles/10.3389/feart.2022.719074/full |
genre |
Antarc* Antarctic Greenland |
genre_facet |
Antarc* Antarctic Greenland |
op_source |
Frontiers in Earth Science volume 10 ISSN 2296-6463 |
op_rights |
https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.3389/feart.2022.719074 |
container_title |
Frontiers in Earth Science |
container_volume |
10 |
_version_ |
1799470205620977664 |