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

J. Paul Winberry, Sridhar Anandakrishnan, Douglas A. Wiens, Richard B. Alley, Knut Christianson

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

The stick-slip motion and associated seismic emissions of Whillans Ice Stream (WIS), West Antarctica are two of the many recent observations of unexpected ice sheet behavior that are challenging traditional models of rapid glacier motion. Here we find that the WIS slip events repeatedly nucleate from a sticky-spot located in the middle of the ice stream, acting similar to an asperity in traditional models of earthquake physics. This region shows less motion than surrounding areas during the inter-slip periods, thus, concentrating stress and producing a pulse of seismic energy at the onset of slip. The propagating rupture breaks through an additional asperity in the northern part of the ice stream, producing another pulse of seismic energy 6-12. min after initiation. Both asperities are regions of higher hydraulic potential than surrounding regions, suggesting they may have greater bed friction due to reduced water lubrication. Tidal pacing of the stress accumulation combined with fault healing controls the applied stress at failure, with higher stress giving faster propagation of the rupture front and higher slip velocities; these differences are reflected in the timing of the teleseismic arrivals. Our results highlight both the great sensitivity of large ice streams to small changes in external forcing and the importance of limited regions of the subglacial bed in controlling their motion, as well as providing insights to the mechanics of repeating earthquakes.

Original languageEnglish (US)
Pages (from-to)283-289
Number of pages7
JournalEarth and Planetary Science Letters
Volume305
Issue number3-4
DOIs
StatePublished - May 15 2011

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'Dynamics of stick-slip motion, Whillans Ice Stream, Antarctica'. Together they form a unique fingerprint.

Cite this