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Depth-Varying Constitutive Properties Observed in an Isothermal Glacier

Marshall, H. P.
Harper, J. T.
Pfeffer, W. T.
Humphrey, Neil
Detailed three-dimensional in-situ measurements of deformation at depth are used to examine the rheology of a 6 x 106 m3 block of temperate glacier ice. Assuming that the viscosity of this ice is primarily dependent on stress, the relationship between inferred stress and measurements of strain-rate above similar to 115 m depth suggest a constitutive relationship with a stress exponent n similar to 1. Deformation below 115 m is described by a non-linear flow law with a power exponent of approximately 3-4. A sharp transition between the two flow regimes is likely caused by a change in the dominant mechanism from superplastic flow, basal slip, and/or diffusional flow near the surface to dislocation and intragranular deformation at depth.
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University of Wyoming. Libraries