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Originally published in Science Express on 17 April 2008
Science 9 May 2008:
Vol. 320. no. 5877, pp. 778 - 781
DOI: 10.1126/science.1153360
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Reports

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,2,3 Matt A. King,4 Dan Lizarralde,1 Maya P. Bhatia5

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 meters 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 subsequent 24 hours. The short-lived dynamic response suggests that an efficient drainage system dispersed the meltwater subglacially. The integrated effect of multiple lake drainages could explain the observed net regional summer ice speedup.

1 Department of Geology and Geophysics, Woods Hole Oceanographic Institution, 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 Earth Sciences and Byrd Polar Research Center, The Ohio State University, 1090 Carmack Road, Columbus, OH 43210–1002, USA.
4 School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
5 Department of Geology and Geophysics, Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program, Woods Hole, MA 02543, USA.

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

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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)