Ambient Seismic Noise Correlation on Iceberg C16, Ross Sea, Antarctica

Abstract:

This study focuses on the ambient noise transmission between 4 seismometer stations distributed on iceberg C16, Ross Sea, Antarctica. These stations were deployed for a 60-day period in 2003/4. The noise source was associated with constant collisions between C16 and a neighboring iceberg, B15A, which was continually being driven into the northeast edge of C16 by ocean tides. The most significant modes of ambient noise transmission were found to be (1) hydroacoustic modes that bounce off the seabed below the iceberg, and (2) flexural-gravity waves that involve the flexural rigidity of the ice layer. The technique used in the study (and in similar studies of the Amery Ice Shelf reported by Zhan and others) provides a new method for studying floating ice with high sensitivity to factors that control hydroacoustic propagation over long distances. It is possible that secular changes in the sub ice ocean layer (such as changes caused by decreasing ice thickness over time) can be observed using ambient noise correlation similar to that performed here. This suggests a way in which seismic observations can constrain variables that characterize how floating ice, and in particular floating ice shelves, buttress glaciers and ice streams that discharge into the ocean.