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Ice fabric in an Antarctic ice stream interpreted from seismic anisotropy
Author(s) -
Smith Emma C.,
Baird Alan F.,
Kendall J. Michael,
Martín Carlos,
White Robert S.,
Brisbourne Alex M.,
Smith Andrew M.
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl072093
Subject(s) - geology , ice stream , anisotropy , ice divide , fast ice , shearing (physics) , sea ice , isotropy , drift ice , ice wedge , ice shelf , geomorphology , arctic ice pack , geophysics , cryosphere , climatology , oceanography , geotechnical engineering , physics , permafrost , quantum mechanics
Here we present new measurements of an anisotropic ice fabric in a fast moving (377 ma −1 ) ice stream in West Antarctica. We use ∼6000 measurements of shear wave splitting observed in microseismic signals from the bed of Rutford Ice Stream, to show that in contrast to large‐scale ice flow models, which assume that ice is isotropic, the ice in Rutford Ice Stream is dominated by a previously unobserved type of partial girdle fabric. This fabric has a strong directional contrast in mechanical properties, shearing 9.1 times more easily along the ice flow direction than across flow. This observed fabric is likely to be widespread and representative of fabrics in other ice streams and large glaciers, suggesting it is essential to consider anisotropy in data‐driven models to correctly predict ice loss and future flow in these regions. We show how passive microseismic monitoring can be effectively used to provide these data.