Basal Conditions on Pine Island Glacier, West Antarctica

Abstract

NERC GEF high-frequency seismic stations were deployed on Pine Island Glacier during two austral summer field campaigns (2006/7 and 2007/8). During the first season, five ISSI SAQS instruments were operated as a single local array; during the second season, four SAQS were deployed at different locations along the length of the glacier. The aim of these deployments was to detect natural seismicity (microearthquakes) arising from the glacier bed, associated with the motion of the ice over the underlying bed. Basal events were detected at five sites; at three sites no events were detected. A number of equipment problems (mostly interference and firmware issues) significantly reduced the amount of useable data recovered during 06/07. Preliminary analysis indicates that bed events occur in a few concentrated swarms separated by prolonged quiet periods. The results appear to show that ice sliding over its bed is associated with the release of far more elastic energy and therefore possibly higher basal friction, than ice flow by deformation of the underlying basal sediment.