Constraints on the lake volume required for hydro-fracture through ice sheets
Figure S3: Comparison of opening geometries for 2 model calculations, dry versus water-filled. (111.1Kb)
Figure S5: A healed crevasse in the field with dimensions typical for a deep water-filled crack. (47.21Mb)
Figure S6: An ice canyon which yields a 3-D view of crack geometry, again with opening geometry consistent with a deep water-filled crack. (57.08Mb)
Krawczynski, Michael J.
Behn, Mark D.
Das, Sarah B.
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Water-filled cracks are an effective mechanism to drive hydro-fractures through thick ice sheets. Crack geometry is therefore critical in assessing whether a supraglacial lake contains a sufficient volume of water to keep a crack water-filled until it reaches the bed. In this study, we investigate fracture propagation using a linear elastic fracture mechanics model to calculate the dimensions of water-filled cracks beneath supraglacial lakes. We find that the cross-sectional area of water-filled cracks increases non-linearly with ice sheet thickness. Using these results, we place volumetric constraints on the amount of water necessary to drive cracks through ∼1 km of sub-freezing ice. For ice sheet regions under little tension, lakes larger than 0.25–0.80 km in diameter contain sufficient water to rapidly drive hydro-fractures through 1–1.5 km of subfreezing ice. This represents ∼98% of the meltwater volume held in supraglacial lakes in the central western margin of the Greenland Ice Sheet.
Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 36 (2009): L10501, doi:10.1029/2008GL036765.