Subglacial melt channels and fracture in the floating part of Pine Island Glacier, Antarctica
Article first published online: 3 AUG 2012
©2012. American Geophysical Union. All Rights Reserved.
Journal of Geophysical Research: Earth Surface (2003–2012)
Volume 117, Issue F3, September 2012
How to Cite
2012), Subglacial melt channels and fracture in the floating part of Pine Island Glacier, Antarctica, J. Geophys. Res., 117, F03012, doi:10.1029/2012JF002360., , , , , , , , and (
- Issue published online: 3 AUG 2012
- Article first published online: 3 AUG 2012
- Manuscript Accepted: 22 JUN 2012
- Manuscript Revised: 14 JUN 2012
- Manuscript Received: 30 JAN 2012
- ice shelf;
 A dense grid of ice-penetrating radar sections acquired over Pine Island Glacier, West Antarctica has revealed a network of sinuous subglacial channels, typically 500 m to 3 km wide, and up to 200 m high, in the ice-shelf base. These subglacial channels develop while the ice is floating and result from melting at the base of the ice shelf. Above the apex of most channels, the radar shows isolated reflections from within the ice shelf. Comparison of the radar data with acoustic data obtained using an autonomous submersible, confirms that these echoes arise from open basal crevasses 50–100 m wide aligned with the subglacial channels and penetrating up to 1/3 of the ice thickness. Analogous sets of surface crevasses appear on the ridges between the basal channels. We suggest that both sets of crevasses were formed during the melting of the subglacial channels as a response to vertical flexing of the ice shelf toward the hydrostatic condition. Finite element modeling of stresses produced after the formation of idealized basal channels indicates that the stresses generated have the correct pattern and, if the channels were formed sufficiently rapidly, would have sufficient magnitude to explain the formation of the observed basal and surface crevasse sets. We conclude that ice-shelf basal melting plays a role in determining patterns of surface and basal crevassing. Increased delivery of warm ocean water into the sub-ice shelf cavity may therefore cause not only thinning but also structural weakening of the ice shelf, perhaps, as a prelude to eventual collapse.