A Novel Over-Sea-Ice Seismic Reflection Survey in McMurdo Sound, Antarctica

During the austral spring of 2005, approximately 28 km of over-sea-ice seismic reflection data were recorded over McMurdo Sound, Antarctica, in support of the ANtarctic geological DRILLing Program (ANDRILL). The 2005 ANDRILL Southern McMurdo Sound Project (SMS) seismic survey incorporated techniques that improved the quality of over-sea-ice seismic data. Previous over-sea-ice seismic experiments have had limited success because of poor source coupling caused by thin sea ice and source bubble-pulse effects caused by explosive seismic sources placed in the water column. To mitigate these problems, a Generator-Injector (GI) air gun was used as the seismic source. The GI air gun was lowered into the water column through holes drilled through the sea ice. The GI air gun minimized the source bubble effects that had plagued previous over-sea-ice experiments in the Antarctic. A 60-channel seismic snow streamer consisting of vertically oriented gimbaled geophones with 25-m takeout spacing was employed to aid rapid data collection. The 2005 SMS seismic survey produced data that accurately tied into existing single-channel marine seismic data and demonstrated the value of the air-gun/snow-streamer system for future over-sea-ice seismic surveys in the Antarctic