Comparison and Calibration of Sea-Swell with Microseism Observations on Ice-Shelf and Land Based Seismometer Stations

Two broadband seismometer records, one from a location near the seaward iceberg-calving front of the Ross Ice Shelf, and the other at Scott Base, on Ross Island are compared. Despite the fact that the two stations are about 300 km apart, and that one is based on floating ice and the other based on an oceanic island, both records clearly display dispersed sea-swell arrival events from storms in the Indian, Pacific and Southern oceans. The ice shelf record displays the 'direct' sea-swell motion, whereas the land record displays primarily the frequency- doubled microseism motion from near-coastally generated Rayleigh waves arising from incoming and reflected swell interference. Two years of austral summer data are compared to calibrate the microseism observations of the land-based seismometer as a proxy for sea swell signal incident on the ice shelf. Preliminary results are used to estimate sea-swell influences on the Ross Ice Shelf at times prior to the deployment of the near-ice-front seismometer, e.g., to hindcast the sea-swell state at the time when B15 and other large icebergs originally calved from the Ross Ice Shelf.