Seismic survey considerations in glaciology
Seismic surveying of glaciers give both englacial and subglacial physical information and is as such an important tool in glaciology. In comparison with the collection of radar data, mainly performed from airborne platforms, seismic data acquisition is a time consuming process practiced in small survey areas and used less frequent. Over the last six years, AWI developed an effective strategy to collect seismic data on glaciers, ice sheets and ice shelves, at a high production rate with a small team (three to five persons) at relatively little effort. The survey areas varied from a 4500m high Alpine saddle to several hundreds of kilometers long transects on the Antarctic ice sheet and adjacent ice shelf. Each survey area has its own possibilities and limitations in the survey set-up. I will reflect upon the hardware, methods, advantages and shortcomings of the performed surveys and will discuss some results. In particular I will focus on the results of two seismic surveys performed in the ablation zone on the West coast of the Greenland Ice Sheet. The main objective here was to characterize the subglacial conditions of the glacier. One site was Russell glacier where ice terminates on land, a second site was Store Glacier, a tidewater glacier in Uummannaq Fjord. In both areas the subglacial hydrology probably plays a key role in the ice dynamics as ice velocities pick up in Summer.