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Tidally driven stick-slip motion in the mouth of Whillans Ice Stream, Antarctica


Bindschadler, RA and Vornberger, PL and King, MA and Padman, L, Tidally driven stick-slip motion in the mouth of Whillans Ice Stream, Antarctica, Annals of Glaciology, 36 pp. 263-272. ISSN 0260-3055 (2003) [Refereed Article]


We show that the ice plain in the mouth of Whillans Ice Stream (formerly Ice Stream B), Antarctica, moves by stick-slip motion. During a spring-tide period, rapid motions regularly occur near high tide and during falling tide. This correlation is weaker during a neap-tide period when the tidal magnitudes are less. Precise timing of these motion events suggests that they propagate through the region with a mean velocity of 88 ms-1. We hypothesize that this speed is associated with the propagation of shear waves through a wet subglacial till. Motion events are also seen on more smoothly flowing floating ice. Event delays are very short between grounded and floating stations, suggesting the events propagate through the ice shelf as an elastic wave. We further hypothesize the events are caused by the interaction of a sticky bed, the accumulation of stored elastic strain through the compression of ice by upstream inflow, and tidal forcing. Motion events seem to be triggered either by reduction of vertical normal stresses at high tide or by the increase of shear stresses from sub-shelf ocean currents during falling tide. Event magnitudes are not related to the length of the preceding quiescent period, suggesting significant viscous dissipation within the till.

Item Details

Item Type:Refereed Article
Keywords:floating ice; glacier flow; ice stream; ice-ocean interaction; tidal cycle; tidewater glacier; Antarctica
Research Division:Earth Sciences
Research Group:Physical geography and environmental geoscience
Research Field:Physical geography and environmental geoscience not elsewhere classified
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:King, MA (Professor Matt King)
ID Code:81800
Year Published:2003
Deposited By:Geography and Environmental Studies
Deposited On:2013-01-08
Last Modified:2013-01-08

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