HR: 0800h
AN: C51B-0389    [Abstracts]
TI: A structural glaciological analysis of the 2002 Larsen B Ice Shelf collapse
AU: * Glasser, N F
EM: nfg@aber.ac.uk
AF: University of Wales, Aberystwyth, Llandinam Building Penglais Campus University of Wales, Aberystwyth, Aberystwyth, SY23 3DB, United Kingdom
AU: Scambos, T A
EM: teds@nsidc.org
AF: National Snow and Ice Data Center, 449 UCB University of Colorado, Boulder, CO 80309, United States
AB: Recent ice-shelf collapse events have been linked to rapid climatic warming of the Antarctic Peninsula. Here we provide a detailed structural glaciological analysis of the changes in surface structures on the Larsen B Ice Shelf ice shelf from a series of visible-channel satellite images acquired between January 2000 and April 2002 and the RAMP mosaic of 1997. Mapped features include the ice-shelf edge, rifts (fractures that penetrate the entire ice shelf), crevasses, longitudinal linear surface structures (also called flow stripes or streaklines), medial moraines, and meltwater features (streams, ponds and dolines). Longitudinal surface structures are particularly important because they can be used to define individual tributary-glacier flow units and their contribution to the ice shelf. Using this approach, we define domains on the ice shelf related to glacier source areas and demonstrate that, prior to collapse, the central Larsen B Ice Shelf consisted of four sutured flow units fed by Crane Glacier, Jorum Glacier, Punchbowl Glacier and Hektoria/Green/Evans Glacier. Between these active glacier-fed flow units were less-active flow units. Prior to collapse, large open rift systems (with floating brash ice) were present ~40 km from the ice-shelf edge at Foyn Point and Cape Disappointment because of the strong lateral shear in the zone separating active and less-active flow units. We suggest that the ice shelf was pre-conditioned to collapse by partial rupturing of the sutures between flow units. Rupturing may have been caused by changes in velocity and shear stresses within the tributary glacier flow units, leading to weaker coupling with islands and peninsulas bounding the shelf.
DE: 0720 Glaciers
DE: 0726 Ice sheets
DE: 0728 Ice shelves
DE: 0774 Dynamics
DE: 0799 General or miscellaneous
SC: Cryosphere [C]
MN: 2007 Fall Meeting