Near-surface environmentally forced changes in the Ross Ice Shelf observed with ambient seismic noise

J. Chaput; R. C. Aster; D. McGrath; M.G.W. Baker; Robert E. Anthony; P. Gerstoft; P. Bromirski; A. Nyblade; R.A. Stephen; D. Wiens

doi:10.1029/2018gl079665

USGS · 70203348

Near-surface environmentally forced changes in the Ross Ice Shelf observed with ambient seismic noise

J. Chaput·R. C. Aster·D. McGrath·M.G.W. Baker·Robert E. Anthony·P. Gerstoft·P. Bromirski·A. Nyblade·R.A. Stephen·D. Wiens

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Abstract

Continuous seismic observations across the Ross Ice Shelf reveal ubiquitous ambient res- onances at frequencies >5 Hz. These firn-trapped surface wave signals arise through wind and snow bedform interactions coupled with very low velocity structures. Progressive and long-term spectral changes are associated with surface snow redistribution by wind and with a January 2016 regional melt event. Modeling demonstrates high spectral sen- sitivity to near-surface (top several m) elastic parameters. We propose that spectral peak changes arise from surface snow redistribution in wind events, and to velocity drops re- flecting snow lattice weakening near 0◦C for the melt event. Percolation-related refrozen layers and layer thinning may also contribute to long-term spectral changes after the melt event. Single-station observations are inverted for elastic structure for multiple stations across the ice shelf. High-frequency ambient noise seismology presents opportunities for continuous assessment of near surface ice shelf or other firn environments.

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J. Chaput, R. C. Aster, D. McGrath, M.G.W. Baker, Robert E. Anthony, P. Gerstoft, P. Bromirski, A. Nyblade, R.A. Stephen, D. Wiens. 2018-10-16. Near-surface environmentally forced changes in the Ross Ice Shelf observed with ambient seismic noise. https://doi.org/10.1029/2018gl079665

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