Tidal bending of glaciers: A linear viscoelastic approach

Abstract

In theoretical treatments of tidal bending of floating glaciers, the glaciers is usually modelled as an elastic beam with uniform thickness, resting on an elastic foundation. With a few exceptions, values of elastic (Young's) modulus E of ice derived from tidal deflection records of floating glaciers are in the range 09-3 GPa. It has therefore been suggested that the elastic-beam model with a single value of E ≈ l GPa adequately describes tidal bending of glaciers. In contrast, laboratory with ice give E = 9.3 GPa, i.e. 3-10 times higher than the glaciers-derived values. This suggests that ice creep may have a significant influence on tidal bending of glaciers. Moreover, detailed tidal-deflection and tilt data from Nioghalvlerdsfjorden glacier, northeast Greenland, cannot be explained by elastic-beam theory. We present a theory of tidal bending of glaciers based on linear viscoelastic-beam theory. A four-element, linear viscoelastic model for glacier ice with a reasonable choice of model parameters can explain the observed tidal flexure data. Implications of the viscoelastic response of glaciers to tidal forcing are discussed briefly. © International Glaciological Society.