Geophysical Research Letters
American Geophysical Union
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 about 115 m depth suggest a constitutive relationship with a stress exponent n about 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.
© 2002 by the American Geophysical Union
Marshall, H. P., J. T. Harper, W. T. Pfeffer, and N. F. Humphrey, Depth-varying constitutive properties observed in an isothermal glacier, Geophys. Res. Lett., 29(23), 2146, doi:10.1029/2002GL015412, 2002.