Abstract
The West Antarctic Ice Sheet (WAIS) is the only remaining marine ice sheet; i.e., its base is located well bellow sea level, making this ice sheet potentially unstable with respect to rising sea level. The ice discharge from the WAIS is provided mostly via ice streams, which can be distinguished due to relatively fast ice movement (hundreds meters annually vs. meters for the rest of the ice sheet). The understanding of triggering mechanisms for fast ice flow in ice streams is crucial for predicting the future behavior of the WAIS. The presence of lubricated sediments beneath the ice is thought to be a necessary condition for the initiation of fast ice flow; thus water must-be a component of the system.

The study area for this project is the onset region of the Kamb Ice Stream (formally Ice Stream C) of West Antarctica. This ice stream is known to be stagnant for about 150 years. Radar sounding over the onset region of this ice stream shows the bright sub-ice reflection, suggesting the presence of water beneath the ice sheet. This region of high subglacial echo strength coincides with an area of anomalous height in gravity anomaly. The magnetic field over this area also shows a complex pattern of anomalies. The main purpose of this project is to evaluate the crustal structure beneath the onset of Kamb Ice Stream based on the joint interpretation of airborne gravity and magnetic data and to establish its relevance to the availability of water for ice stream initiation.