Dynamics of stick–slip motion, Whillans Ice Stream, Antarctica

AbstractA puzzling phenomenon of ice-stream flow is the stick–slip motion displayed by Whillans Ice Stream (WIS), West Antarctica. In this study we test the hypothesis that the WIS stick–slip motion has features similar to those of other known stick–slip systems, and thus might be of the same origin. To do so, we adapt a simple mechanical model widely used in seismology to study classic stick–slip behavior observed in tectonic faults, in which the difference between static and dynamic friction allows for the generation and spatial propagation of abrupt slip events. We show how spatial variability in friction properties, as well as a periodic forcing intended to mimic the effect of tides, can reproduce the observed duration and periodicity of stick–slip motion in an ice stream. An intriguing aspect of the association of WIS with mechanical stick–slip oscillators is that the onset of stick–slip cycling from a condition of permanent slip appears to be associated with the reduction in overall speed of WIS. If this association is true, then stick–slip behavior of WIS is a transitional phase of behavior associated with the ice stream's recent deceleration.

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

Annals of Glaciology ◽

10.3189/172756403781816284 ◽

2003 ◽

Vol 36 ◽

pp. 263-272 ◽

Cited By ~ 49

Author(s):

Robert A. Bindschadler ◽

Patricia L. Vornberger ◽

Matt A. King ◽

Laurie Padman

Keyword(s):

High Tide ◽

Spring Tide ◽

Shear Stresses ◽

Motion Events ◽

Stick Slip ◽

Ice Stream ◽

Whillans Ice Stream ◽

Stick Slip Motion ◽

Tide Period ◽

Slip Motion

AbstractWe 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 m s−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.

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Tidal pacing, skipped slips and the slowdown of Whillans Ice Stream, Antarctica

Journal of Glaciology ◽

10.3189/2014jog14j038 ◽

2014 ◽

Vol 60 (222) ◽

pp. 795-807 ◽

Cited By ~ 38

Author(s):

J. Paul Winberry ◽

Sridhar Anandakrishnan ◽

Richard B. Alley ◽

Douglas A. Wiens ◽

Martin J. Pratt

Keyword(s):

Elastic Strain ◽

Temporal Evolution ◽

Flow Speed ◽

Stick Slip ◽

Ice Stream ◽

Steady Rate ◽

Decadal Scale ◽

Whillans Ice Stream ◽

Stick Slip Motion

AbstractWe summarize new observations of the deceleration and stick–slip motion of Whillans Ice Stream (WIS), Antarctica. We refine the location of the large sticky spots that resist motion between slip events, the locations of which are controlled by the patterns of subglacial water flow. Our examination of the long-term velocity time series for the ice stream reveals that the decadal-scale deceleration is not occurring at a steady rate, but varies at the sub-decadal timescale. This unsteady deceleration modulates the temporal evolution of a broad (~50 km across) surface-elevation bulge forming at the junction between the relatively narrow upstream portion of the ice stream and broad ice plain that constitutes the downstream end of WIS. Comparison of observations from April 2003 and November 2010 reveals significant changes in the tidally modulated stick–slip cycle that regulates motion on the ice plain. We observe that the timing of slip events has become less regular in response to decreased flow speed in the upstream portions of the ice stream. The decreased regularity of slip events has reduced the release of stored elastic strain during slip events, increasing the rate of deceleration.

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Simultaneous teleseismic and geodetic observations of the stick–slip motion of an Antarctic ice stream

Nature ◽

10.1038/nature06990 ◽

2008 ◽

Vol 453 (7196) ◽

pp. 770-774 ◽

Cited By ~ 99

Author(s):

Douglas A. Wiens ◽

Sridhar Anandakrishnan ◽

J. Paul Winberry ◽

Matt A. King

Keyword(s):

Stick Slip ◽

Ice Stream ◽

Stick Slip Motion ◽

Slip Motion

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A Viscoelastic Model of Ice Stream Flow with Application to Stick-Slip Motion

Frontiers in Earth Science ◽

10.3389/feart.2016.00002 ◽

2016 ◽

Vol 4 ◽

Cited By ~ 5

Author(s):

Ryan T. Walker ◽

Byron R. Parizek ◽

Richard B. Alley ◽

Sophie M. J. Nowicki

Keyword(s):

Stream Flow ◽

Viscoelastic Model ◽

Stick Slip ◽

Ice Stream ◽

Stick Slip Motion ◽

Slip Motion

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Stick-slip motion of an Antarctic Ice Stream: The effects of viscoelasticity

Journal of Geophysical Research Earth Surface ◽

10.1002/2014jf003132 ◽

2014 ◽

Vol 119 (7) ◽

pp. 1564-1580 ◽

Cited By ~ 17

Author(s):

D. N. Goldberg ◽

C. Schoof ◽

O. V. Sergienko

Keyword(s):

Stick Slip ◽

Ice Stream ◽

Stick Slip Motion ◽

Slip Motion

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Towards a description of stick-slip motion using a viscoelastic Full Stokes model

10.5194/egusphere-egu21-11898 ◽

2021 ◽

Author(s):

Cristina Gerli ◽

Sebastian Rosier ◽

Hilmar Gudmundsson

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Element Model ◽

Stick Slip ◽

Ice Stream ◽

Basal Sliding ◽

Rate And State Friction ◽

Set Up ◽

Stick Slip Motion ◽

Slip Motion

<p>The lightly grounded portion of the Whillans Ice Stream (WIS, Siple Coast, Antarctica), has a unique stick-slip motion behaviour, where prolonged stagnant phases (6-25 hrs) are interrupted by rapid active slip events (up to 0.5 m in < 1 hr).&#160; WIS is also interesting because it is currently stagnating, presenting an important opportunity to understand this behaviour and its effect on future sea level rise. Detailed observations and a variety of modelling approaches have revealed the complexity of stick-slip behaviour and the importance of correctly representing ice rheology, ice stream geometry, spatial variability of friction strength, and boundary conditions. Currently, no single model exists that can fully replicate all the observed features of stick-slip motion as observed on the Whillans Ice Plain.&#160;Here we describe a full-Stokes viscoelastic finite element model that has been previously used to explore tidal modulation of ice stream flow, and which can overcome some of the assumptions adopted in previous work. The model is&#160; set up for an idealised configuration of the Whillans Ice Plain, with the aim of exploring how the inclusion of relevant additional physics affects stick-slip motion for a rate and state friction law, and whether other sliding laws could also explain the observed motion. Ultimately, this modelling work aims to put tighter constraints on the conditions required to initiate stick-slip behaviour, improving our understanding of basal sliding and future sea level rise.</p>

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