Radar, electromagnetic, and active seismic investigation of a propagating ice shelf rift tip

A rift system has been growing inward from the seaward edge of the Amery Ice Shelf in East Antarctica for over twenty years. Currently active, the 'Loose Tooth' rift system is in the process of calving off an iceberg that will be at least 30 x 30 km in size. Over the past five field seasons passive seismic and geodetic measurements have been made at one of the propagating tips of the rift system. During the 2006-07 field season pilot Ground Penetrating Radar and Transient Electromagnetic (TEM) data were collected over and near that propagating rift tip, to provide complimentary constraints regarding the internal structure of the ice shelf and to look for evidence of penetration of electrically conductive seawater into the rift from below. In another auxiliary experiment, small charges were set off near the rift tip to provide calibration and velocity structure information for the primary passive seismic data set. Preliminary results are presented in comparison with the passive seismic and geodetic results, as well as a discussion of practical constraints and challenges in collecting these types of data at an ice shelf rift.