Frictional Origin of Slip Events of the Whillans Ice Stream, Antarctica
International audience Ice sheet evolution depends on subglacial conditions, with the ice-bed interface's strength exerting an outsized role on the ice dynamics. Along fast-flowing glaciers, this strength is often controlled by the deformation of subglacial till, making quantification of spatia...
Published in: | Geophysical Research Letters |
---|---|
Main Authors: | , , , , |
Other Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2021
|
Subjects: | |
Online Access: | https://hal.archives-ouvertes.fr/hal-03327192 https://hal.archives-ouvertes.fr/hal-03327192/document https://hal.archives-ouvertes.fr/hal-03327192/file/Geophysical%20Research%20Letters%20-%202021%20-%20Guerin%20-%20Frictional%20Origin%20of%20Slip%20Events%20of%20the%20Whillans%20Ice%20Stream%20Antarctica.pdf https://doi.org/10.1029/2021GL092950 |
Summary: | International audience Ice sheet evolution depends on subglacial conditions, with the ice-bed interface's strength exerting an outsized role on the ice dynamics. Along fast-flowing glaciers, this strength is often controlled by the deformation of subglacial till, making quantification of spatial variations of till strength essential for understanding ice-sheet contribution to sea-level. This task remains challenging due to a lack of in situ observations. We analyze continuous seismic data from the Whillans Ice Plain (WIP), West Antarctica, to uncover spatio-temporal patterns in subglacial conditions. We exploit tidally modulated stick-slip events as a natural source of sliding variability. We observe a significant reduction of the till seismic wave-speed between the WIP sticky-spots. These observations are consistent with a poroelastic model where the bed experiences relative porosity and effective pressure increases of >11% during stick-slips. We conclude that dilatant strengthening appears to be an essential mechanism in stabilizing the rapid motion of fast-flowing ice streams. |
---|