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Published Online April 17, 2008
Science DOI: 10.1126/science.1153360

Reports

Submitted on November 26, 2007
Accepted on March 31, 2008

Fracture Propagation to the Base of the Greenland Ice Sheet During Supraglacial Lake Drainage

Sarah B. Das 1*, Ian Joughin 2, Mark D. Behn 1, Ian M. Howat 2, Matt A. King 3, Dan Lizarralde 1, Maya P. Bhatia 4

1 Department of Geology and Geophysics, Woods Hole Oceanographic Institute, Woods Hole, MA 02543, USA.
2 Polar Science Center, Applied Physics Lab, University of Washington, 1013 NE 40th Street, Seattle, WA 98105–6698, USA.
3 School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
4 Department of Geology and Geophysics, MIT/WHOI Joint Program, Woods Hole, MA 02543, USA.

* To whom correspondence should be addressed.
Sarah B. Das , E-mail: sdas{at}whoi.edu

Surface meltwater that reaches the base of an ice sheet creates a mechanism for the rapid response of ice flow to climate change. The process whereby such a pathway is created through thick, cold ice has not, however, been previously observed. We describe the rapid (<2 hours) drainage of a large supraglacial lake down 980 m through to the bed of the Greenland Ice Sheet initiated by water-driven fracture propagation evolving into moulin flow. Drainage coincided with increased seismicity, transient acceleration, ice sheet uplift and horizontal displacement. Subsidence and deceleration occurred over the following 24 hours. The short-lived dynamic response suggests an efficient drainage system dispersed the meltwater subglacially. The integrated effect of multiple lake drainages could explain the observed net regional summer ice speedup.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Large and Rapid Melt-Induced Velocity Changes in the Ablation Zone of the Greenland Ice Sheet.
R. S. W. van de Wal, W. Boot, M. R. van den Broeke, C. J. P. P. Smeets, C. H. Reijmer, J. J. A. Donker, and J. Oerlemans (2008)
Science 321, 111-113
   Abstract »    Full Text »    PDF »
Seasonal Speedup Along the Western Flank of the Greenland Ice Sheet.
I. Joughin, S. B. Das, M. A. King, B. E. Smith, I. M. Howat, and T. Moon (2008)
Science 320, 781-783
   Abstract »    Full Text »    PDF »


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Science. ISSN 0036-8075 (print), 1095-9203 (online)