Abstract
Cryoseismic studies are increasingly being used to measure intraglacial
deformation, reliant on lab observations that sheared ice crystals
create seismic ‘fast’ directions at predictable orientations to the flow
direction. However, icy materials are often in contact with liquid
phases that modify seismic properties of the aggregate. Previous studies
describing seismic anisotropy in temperate ice considered how melt
affects the orientation of solid ice, but not the orientation of the
melt itself. We simulated microstructural shear deformation of partially
molten ice with variable melt orientations, and calculated resultant
seismic properties. Our results demonstrate that ≤ 3.5% 3D melt
concentration changes the fast direction of a deforming icy aggregate,
and higher degrees can completely overprint the solid-induced fast
direction. Melt orientation is thus a key control on the seismic
anisotropy of deforming partially molten ice, and solid-based methods
may incorrectly estimate the magnitude and direction of subsurface flow
in temperate icy bodies.