Ground Penetrating Radar (GPR) surveys of a an ice rise on the southern McMurdo Ice Shelf, Antarctica.

A topographic rise was observed on satellite imagery and ground traverses of the southern McMurdo Ice Shelf, part way between the SW tip of Black Island and the north shore of Minna Bluff was investigated in January 2005 using Ground Penetrating Radar (GPR) and GPS. Nine 50 MHz GPR profiles ranging from 1.5 to 2.5 km in length, were collected using a snowmobile-towed Sensors & Software Pulse Ekko 100 radar system. The GPR transects were configured in an obliquely crossing network, with accompanying topographic information provided by continuous kinematic GPS. Reflectors identified on the GPR profiles indicate that the ice shelf in this locality is grounded on an asymmetric crater-shaped bathymetric feature. Following conversion of two-way-travel-times (TWTT) to depth, it appears that the crater rims are ~50 m below the ice shelf surface while the crater floor is undulating at ~100 m depth. The presence of this pinning point and its morphology has implications for local ice shelf flow characteristics and for understanding the dynamics of the McMurdo Ice Shelf as a whole. Eight out of 44 ice movement poles established in the 02/03 and 03/04 season were resurveyed using differential GPS. This study builds on studies investigating the characteristics and processes of the southern McMurdo Ice Shelf.