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Easy Glide in Shear Bands from a Calving Ice Wall Duplicated in Laboratory Creep Experiments

Published online by Cambridge University Press:  20 January 2017

Terence Hughes
Affiliation:
Institute for Quaternary Studies and Department of Geological Sciences, University of Maine, Orono, Maine 04469, U.S.A.
Masayuki Nakagawa
Affiliation:
Department of Physics, Toyama University, Gofuku 3190, Toyama, Japan
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Abstract

Type
Abstracts of Papers Presented at the Symposium but not Published in this Volume
Copyright
Copyright © International Glaciological Society 1989

Slab calving from an ice wall on Deception Island (63.0°S, 60.6°W) has been related to a bending moment at the top of the ice wall that produced nearly vertical shear bands across which shear offset decreases to zero at the bed and in which strain-rates up to 600/a were measured. These shear bands and strain-rates were duplicated in laboratory creep experiments at shear stresses of 100 kPa or more, after a shear strain of about 0.4 at the end of recrystallization. Recrystallization began at a shear strain of about 0.1 when the strain-rate was about 1.9/a, which increases to 24.0/a after recrystallization. Halving the shear stress suppressed recrystallization. Prior to recrystallization, n = 2.17 in the flow law,

. From this, a shear stress of 228 kPa was computed for
in a shear band on the ice wall.