Insights into seismic anisotropy of temperate ice during simple shear deformation


Contact
Ilka.Weikusat [ at ] awi.de

Abstract

The ice mass balances of Antarctic and Greenland ice sheets represent the largest uncertainty for predicting future sea-level rise. Understanding how ice flows from the accumulation to the ablation zone is therefore crucial for correctly estimating the changing mass in polar ice-sheets. On Earth, ice crystals have a hexagonal symmetry (ice lh) with a strong anisotropy favouring basal slip. This results in a progressive development of a vertical c-axis preferred orientation (LPO) of ice polycrystalline aggregates during deformation. In depth, the elastic anisotropy of polycrystalline ice gradually increases due the development of a vertical LPO. Observations of P-wave (Vp) and S-wave (Vs) velocities in ice sheets reveal a strong decrease of ~25% of Vs in depth, while Vp remains approximately constant. According to Wittlinger and Farra (2015) the low Vs may be due to the presence of unfrozen liquids resulting from pre-melting at grain joints and/or melting of chemical solutions buried in ice. Although previous studies of two-phase rocks (including melt and water) show that seismic velocities depend on both LPO and water content, studies on the effect of melt on polar ice seismic velocity are scarce. In this contribution we investigate the changes in P- and faster S-wave velocities during deformation of polycrystalline ice with different melt fractions.



Item Type
Conference (Poster)
Authors
Divisions
Primary Division
Programs
Primary Topic
Research Networks
Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
Tectonics Community Science Workshop, 27 Jul 2020 - 31 Jul 2020, virtual.
Eprint ID
52729
Cite as
Llorens, M. G. , Griera, A. , Gomez-Rivas, E. , Bons, P. D. , Weikusat, I. , Prior, D. J. and Lebensohn, R. (2020): Insights into seismic anisotropy of temperate ice during simple shear deformation , Tectonics Community Science Workshop, virtual, 27 July 2020 - 31 July 2020 .


Share

Research Platforms

Campaigns


Actions
Edit Item Edit Item