Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica
We use high resolution, ground-based observations of ice displacement to investigate ice deformation across the floating left-lateral shear margin of Priestley Glacier, Terra Nova Bay, Antarctica. Bare ice conditions allow us to fix survey marks directly to the glacier surface. A combination of cont...
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ftdoajarticles:oai:doaj.org/article:631b573be59c44b6967adf80eaae62c6 2023-05-15T14:03:12+02:00 Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica Holly Still Christina Hulbe Martin Forbes David J. Prior M. Hamish Bowman Bia Boucinhas Lisa Craw Daeyeong Kim Franz Lutz Robert Mulvaney Rilee E. Thomas 2022-05-01T00:00:00Z https://doi.org/10.3389/feart.2022.828313 https://doaj.org/article/631b573be59c44b6967adf80eaae62c6 EN eng Frontiers Media S.A. https://www.frontiersin.org/articles/10.3389/feart.2022.828313/full https://doaj.org/toc/2296-6463 2296-6463 doi:10.3389/feart.2022.828313 https://doaj.org/article/631b573be59c44b6967adf80eaae62c6 Frontiers in Earth Science, Vol 10 (2022) shear margin tides ice deformation elastic model ice flexure GNSS Science Q article 2022 ftdoajarticles https://doi.org/10.3389/feart.2022.828313 2022-12-31T02:39:39Z We use high resolution, ground-based observations of ice displacement to investigate ice deformation across the floating left-lateral shear margin of Priestley Glacier, Terra Nova Bay, Antarctica. Bare ice conditions allow us to fix survey marks directly to the glacier surface. A combination of continuous positioning of a local reference mark, and repeat positioning of a network of 33 stakes installed across a 2 km width of the shear margin are used to quantify shear strain rates and the ice response to tidal forcing over an 18-day period. Along-flow velocity observed at a continuous Global Navigation Satellite Systems (GNSS) station within the network varies by up to ∼30% of the mean speed (±28 m a−1) over diurnal tidal cycles, with faster flow during the falling tide and slower flow during the rising tide. Long-term deformation in the margin approximates simple shear with a small component of flow-parallel shortening. At shorter timescales, precise optical techniques allow high-resolution observations of across-flow bending in response to the ocean tide, including across-flow strains on the order of 10–5. An elastodynamic model informed by the field observations is used to simulate the across-flow motion and deformation. Flexure is concentrated in the shear margin, such that a non-homogeneous elastic modulus is implied to best account for the combined observations. The combined pattern of ice displacement and ice strain also depends on the extent of coupling between the ice and valley sidewall. These conclusions suggest that investigations of elastic properties made using vertical ice motion, but neglecting horizontal displacement and surface strain, will lead to incorrect conclusions about the elastic properties of ice and potentially over-simplified assumptions about the sidewall boundary condition. Article in Journal/Newspaper Antarc* Antarctica Priestley Glacier Directory of Open Access Journals: DOAJ Articles Terra Nova Bay Priestley ENVELOPE(161.883,161.883,-75.183,-75.183) Priestley Glacier ENVELOPE(163.367,163.367,-74.333,-74.333) Frontiers in Earth Science 10 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
shear margin tides ice deformation elastic model ice flexure GNSS Science Q |
spellingShingle |
shear margin tides ice deformation elastic model ice flexure GNSS Science Q Holly Still Christina Hulbe Martin Forbes David J. Prior M. Hamish Bowman Bia Boucinhas Lisa Craw Daeyeong Kim Franz Lutz Robert Mulvaney Rilee E. Thomas Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica |
topic_facet |
shear margin tides ice deformation elastic model ice flexure GNSS Science Q |
description |
We use high resolution, ground-based observations of ice displacement to investigate ice deformation across the floating left-lateral shear margin of Priestley Glacier, Terra Nova Bay, Antarctica. Bare ice conditions allow us to fix survey marks directly to the glacier surface. A combination of continuous positioning of a local reference mark, and repeat positioning of a network of 33 stakes installed across a 2 km width of the shear margin are used to quantify shear strain rates and the ice response to tidal forcing over an 18-day period. Along-flow velocity observed at a continuous Global Navigation Satellite Systems (GNSS) station within the network varies by up to ∼30% of the mean speed (±28 m a−1) over diurnal tidal cycles, with faster flow during the falling tide and slower flow during the rising tide. Long-term deformation in the margin approximates simple shear with a small component of flow-parallel shortening. At shorter timescales, precise optical techniques allow high-resolution observations of across-flow bending in response to the ocean tide, including across-flow strains on the order of 10–5. An elastodynamic model informed by the field observations is used to simulate the across-flow motion and deformation. Flexure is concentrated in the shear margin, such that a non-homogeneous elastic modulus is implied to best account for the combined observations. The combined pattern of ice displacement and ice strain also depends on the extent of coupling between the ice and valley sidewall. These conclusions suggest that investigations of elastic properties made using vertical ice motion, but neglecting horizontal displacement and surface strain, will lead to incorrect conclusions about the elastic properties of ice and potentially over-simplified assumptions about the sidewall boundary condition. |
format |
Article in Journal/Newspaper |
author |
Holly Still Christina Hulbe Martin Forbes David J. Prior M. Hamish Bowman Bia Boucinhas Lisa Craw Daeyeong Kim Franz Lutz Robert Mulvaney Rilee E. Thomas |
author_facet |
Holly Still Christina Hulbe Martin Forbes David J. Prior M. Hamish Bowman Bia Boucinhas Lisa Craw Daeyeong Kim Franz Lutz Robert Mulvaney Rilee E. Thomas |
author_sort |
Holly Still |
title |
Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica |
title_short |
Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica |
title_full |
Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica |
title_fullStr |
Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica |
title_full_unstemmed |
Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica |
title_sort |
tidal modulation of a lateral shear margin: priestley glacier, antarctica |
publisher |
Frontiers Media S.A. |
publishDate |
2022 |
url |
https://doi.org/10.3389/feart.2022.828313 https://doaj.org/article/631b573be59c44b6967adf80eaae62c6 |
long_lat |
ENVELOPE(161.883,161.883,-75.183,-75.183) ENVELOPE(163.367,163.367,-74.333,-74.333) |
geographic |
Terra Nova Bay Priestley Priestley Glacier |
geographic_facet |
Terra Nova Bay Priestley Priestley Glacier |
genre |
Antarc* Antarctica Priestley Glacier |
genre_facet |
Antarc* Antarctica Priestley Glacier |
op_source |
Frontiers in Earth Science, Vol 10 (2022) |
op_relation |
https://www.frontiersin.org/articles/10.3389/feart.2022.828313/full https://doaj.org/toc/2296-6463 2296-6463 doi:10.3389/feart.2022.828313 https://doaj.org/article/631b573be59c44b6967adf80eaae62c6 |
op_doi |
https://doi.org/10.3389/feart.2022.828313 |
container_title |
Frontiers in Earth Science |
container_volume |
10 |
_version_ |
1766273760219889664 |