Ross Ice Shelf Icequakes Associated With Ocean Gravity Wave Activity

Abstract

Gravity waves impacting ice shelves illicit a suite of responses that can affect ice shelf integrity. Broadband seismometers deployed on the Ross Ice Shelf, complemented by a near-icefront seafloor hydrophone, establish the association of strong icequake activity with ocean gravity wave amplitudes (A(G)) below 0.04 Hz. The Ross Ice Shelf-front seismic vertical displacement amplitudes (A(SV)) are well correlated with A(G), allowing estimating the frequency-dependent transfer function from gravity wave amplitude to icefront vertical displacement amplitude (T-GSV(f)). T-GSV(f) is 0.6-0.7 at 0.001-0.01 Hz but decreases rapidly at higher frequencies. Seismicity of strong icequakes exhibits spatial and seasonal associations with different gravity wave frequency bands, with the strongest icequakes observed at the icefront primarily during the austral summer when sea ice is minimal and swell impacts are strongest.