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Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica

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Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica
Other Titles
측면전단 가장부의 주기적 변화: 남극 프리슬리빙하
Holly Still
Christina Hulbe
Martin Forbes
David J. Prior
Hamish Bowman
Bia Boucinhas
Lisa Craw
Franz Lutz
Robert Mulvaney
Rilee Thomas
AntarcticaGNSSPriestley Glacierelastic modelice deformationice flexureshear margintides
Issue Date
Holly Still, et al. 2022. "Tidal Modulation of a Lateral Shear Margin: Priestley Glacier, Antarctica". FRONTIERS IN EARTH SCIENCE, 10(1): 1-17.
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 ~50% of the mean speed (±46 ma?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.
Jang Bogo Station
Appears in Collections  
2022-2022, Investigating anthropogenic and natural characteristics of atmosphere-ice sheet exchanges using the international deep ice coring network (22-22) / Han, Yeongcheol (PE22100)
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