East Greenland Glacier Dynamics: An Interdisciplinary Study of Helheim Glacier

Our study of Helheim glacier was initiated in 2006 primarily to investigate the source of glacial earthquakes. Glacial earthquakes appear to be sensitive to climate parameters and could potentially serve as an "early warning" for changes in the dynamics of the Arctic glaciers. However, glacial earthquakes are only useful for this purpose if we understand the mechanisms controlling them. Interdisciplinary project groups from Denmark, Spain, and the US have joined forces to cover a wide range of observables related to glacial earthquakes and glacier dynamics. The study involves seismology, geodesy, glaciology, and climatology. The seismic waves from the glacial earthquakes are detected at teleseismic distances as well as by regional and local seismographs in Greenland. The higher frequency waves from glacial earthquakes have only reasonable signal to noise ratios at distances less than a few hundred km away, whereas the lower frequencies survive to teleseismic distances. The velocity field of Helheim glacier is measured through three summer field seasons using high-rate GPS measurements directly on the ice. Automatic Weather Stations record a wide range of meteorological parameters for the purpose of looking for correlations between changes in glacier dynamics and changes in melting. Lidar data were collected in 2007 and interpreted jointly with ASTER data. It is difficult to penetrate the highly crevassed part of the glacier with radar, so in order to get a better estimate of the thickness of the ice a gravity profile was measured across Helheim glacier in 2008. The data and the preliminary results will be presented