HR: 13:40h
AN: C13A-01    [Abstracts]
TI: A Boundary Element Model For Fracture Propagation On The Ronne Ice Shelf, Antarctica
AU: * LeDoux, C M
EM: cledoux@pdx.edu
AF: Portland State University, Department of Geology PO Box 751, Portland, OR 97207-0751 United States
AU: Cruikshank, K M
EM: cruikshankk@pdx.edu
AF: Portland State University, Department of Geology PO Box 751, Portland, OR 97207-0751 United States
AU: Hulbe, C L
EM: chulbe@pdx.edu
AF: Portland State University, Department of Geology PO Box 751, Portland, OR 97207-0751 United States
AB: Large, transverse rifts near the fronts of ice shelves become the planes along which large icebergs calve. At the western front of the Ronne Ice Shelf, such through-cutting rifts are observed to begin as shear-margin fractures along the lateral boundaries of ice streams feeding the shelf. The fractures grow as they are advected through the shelf. Propagation may be episodic (unstable growth followed by arrest) and depends on the stress concentration encountered at the fracture tip. Fracture geometry may record changing stress conditions at the upstream site of fracture initiation, distortion due to advection, or changes in local stress state due to inhomogeneities in the ice and to interaction among fractures. Here, a set of fractures advecting from the Evans Ice Stream to the front of the Ronne Ice Shelf are investigated using propagation models based on linear elastic fracture mechanics. A boundary element model is developed for this purpose, using the displacement discontinuity method. Fractures and related features are digitized from stacked composite MODIS (Moderate Resolution Imaging Spectroradiometer) satellite images. Episodic fracture-tip propagation is found to depend on inhomogeneities in the ice shelf.
DE: 0728 Ice shelves
DE: 0798 Modeling
SC: Cryosphere [C]
MN: Fall Meeting 2005