BEAMISH

In this project we will address significant aspects of ice stream flow and West Antarctic Ice Sheet stability. Our aims are to provide an observational basis for understanding the fast ice stream flow mechanism and to interpret ice sheet history. Using a hot-water drill we will penetrate an ice stream to its base, sample the ice and the subglacial material, deploy instruments within the ice and the bed, and conduct surface geophysical surveys. Sufficient aperture and fold are essential for accurate event location, reliable focal mechanism discrimination and also anisotropy characterisation. We will deploy 35 Reftek RT130 recorders with 4.5Hz geophones for a polar summer. In addition, we will deploy two sensors over-winter prior to drilling to record background levels. A passive seismic array at the surface will allow us to address the following questions: - What is the relative importance of ice creep, basal sliding and bed deformation in the flow of the ice stream? - What is the nature of the basal hydrological system? - What is the thermal regime of the ice and the bed?