Cyclic Effective Pressure Loading Impacts Glacial Slip Over Deformable Beds
Abstract Tidal fluctuations at the grounding zones of marine‐terminating glaciers induce oscillations in effective pressure at the glacier bed, altering ice‐till coupling and glacial slip. Glaciers slipping atop deformable beds with oscillatory pressure fluctuations can generate a transient porewate...
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| Format: | Article |
| Language: | English |
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Wiley
2025-04-01
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| Series: | Geophysical Research Letters |
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| Online Access: | https://doi.org/10.1029/2024GL113658 |
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| author | N. Morgan‐Witts D. D. Hansen L. K. Zoet M. Haseloff |
| author_facet | N. Morgan‐Witts D. D. Hansen L. K. Zoet M. Haseloff |
| author_sort | N. Morgan‐Witts |
| collection | DOAJ |
| description | Abstract Tidal fluctuations at the grounding zones of marine‐terminating glaciers induce oscillations in effective pressure at the glacier bed, altering ice‐till coupling and glacial slip. Glaciers slipping atop deformable beds with oscillatory pressure fluctuations can generate a transient porewater pressure feedback within the underlying till, affecting bed coupling and the yield stress of the till. The influence of this transient feedback can range from negligible to dominating glacier slip; however, little is known about the governing mechanics. We used a cryogenic ring shear device to simulate basal slip under oscillating pressure conditions with varying amplitudes to directly measure drag under transient forcing. We find a path dependence (hysteresis) within the shear stress–effective pressure relationship and a greater extent of deformation within till undergoing cyclic loading compared to static loading. Importantly, shear stress is greater when effective pressure is unloading, indicating potential stabilizing feedbacks during rising tides or anomalous fluid pressure spikes. |
| format | Article |
| id | doaj-art-fb6d30f74ee04710a78f660a562c5f75 |
| institution | Kabale University |
| issn | 0094-8276 1944-8007 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geophysical Research Letters |
| spelling | doaj-art-fb6d30f74ee04710a78f660a562c5f752025-08-20T03:39:03ZengWileyGeophysical Research Letters0094-82761944-80072025-04-01528n/an/a10.1029/2024GL113658Cyclic Effective Pressure Loading Impacts Glacial Slip Over Deformable BedsN. Morgan‐Witts0D. D. Hansen1L. K. Zoet2M. Haseloff3Department of Geoscience University of Wisconsin‐Madison Madison WI USADepartment of Geoscience University of Wisconsin‐Madison Madison WI USADepartment of Geoscience University of Wisconsin‐Madison Madison WI USADepartment of Geoscience University of Wisconsin‐Madison Madison WI USAAbstract Tidal fluctuations at the grounding zones of marine‐terminating glaciers induce oscillations in effective pressure at the glacier bed, altering ice‐till coupling and glacial slip. Glaciers slipping atop deformable beds with oscillatory pressure fluctuations can generate a transient porewater pressure feedback within the underlying till, affecting bed coupling and the yield stress of the till. The influence of this transient feedback can range from negligible to dominating glacier slip; however, little is known about the governing mechanics. We used a cryogenic ring shear device to simulate basal slip under oscillating pressure conditions with varying amplitudes to directly measure drag under transient forcing. We find a path dependence (hysteresis) within the shear stress–effective pressure relationship and a greater extent of deformation within till undergoing cyclic loading compared to static loading. Importantly, shear stress is greater when effective pressure is unloading, indicating potential stabilizing feedbacks during rising tides or anomalous fluid pressure spikes.https://doi.org/10.1029/2024GL113658till deformationsediment deformationcyclic loadingbasal slipsubglacialhysteresis |
| spellingShingle | N. Morgan‐Witts D. D. Hansen L. K. Zoet M. Haseloff Cyclic Effective Pressure Loading Impacts Glacial Slip Over Deformable Beds Geophysical Research Letters till deformation sediment deformation cyclic loading basal slip subglacial hysteresis |
| title | Cyclic Effective Pressure Loading Impacts Glacial Slip Over Deformable Beds |
| title_full | Cyclic Effective Pressure Loading Impacts Glacial Slip Over Deformable Beds |
| title_fullStr | Cyclic Effective Pressure Loading Impacts Glacial Slip Over Deformable Beds |
| title_full_unstemmed | Cyclic Effective Pressure Loading Impacts Glacial Slip Over Deformable Beds |
| title_short | Cyclic Effective Pressure Loading Impacts Glacial Slip Over Deformable Beds |
| title_sort | cyclic effective pressure loading impacts glacial slip over deformable beds |
| topic | till deformation sediment deformation cyclic loading basal slip subglacial hysteresis |
| url | https://doi.org/10.1029/2024GL113658 |
| work_keys_str_mv | AT nmorganwitts cycliceffectivepressureloadingimpactsglacialslipoverdeformablebeds AT ddhansen cycliceffectivepressureloadingimpactsglacialslipoverdeformablebeds AT lkzoet cycliceffectivepressureloadingimpactsglacialslipoverdeformablebeds AT mhaseloff cycliceffectivepressureloadingimpactsglacialslipoverdeformablebeds |