Constraints on the lake volume required for hydro-fracture through ice sheets

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 similar to 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 similar to 98% of the meltwater volume held in supraglacial lakes in the central western margin of the Greenland Ice Sheet. Citation: Krawczynski, M. J., M. D. Behn, S. B. Das, and I. Joughin (2009), Constraints on the lake volume required for hydro-fracture through ice sheets, Geophys. Res. Lett., 36, L10501, doi: 10.1029/2008GL036765.