Experimental and theoretical fracture mechanics applied to Antarctic ice fracture and surface crevassing

• Published in: Journal of Geophysical Research: Solid Earth
• Main Authors: Rist, M. A., Sammonds, P. R., Murrell, S. A. F., Meredith, P. G., Doake, C. S. M., Oerter, H., Matsuki, K.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union 1999
• Subjects: Antarctic; The Antarctic; Antarctic Peninsula; Ronne Ice Shelf; Antarc*; Filchner Ronne Ice Shelf; Filchner-Ronne Ice Shelf; ice core; Ice Shelf; Ice Shelves
• Online Access: http://nora.nerc.ac.uk/id/eprint/503773/; https://doi.org/10.1029/1998JB900026

Recent disintegration of ice shelves on the Antarctic Peninsula has highlighted the need for a better understanding of ice shelf fracture processes generally. In this paper we present a fracture criterion, incorporating new experimental fracture data, coupled with an ice shelf flow model to predict the spatial distribution of surface crevassing on the Filchner-Ronne Ice Shelf. We have developed experiments that have enabled us to quantify, for the first time, quasi-stable crack growth in Antarctic ice core specimens using a fracture initiation toughness, Kinit, for which crack growth commences. The tests cover a full range of near-surface densities, ρ = 560–871 kg m−3 (10.9–75.7 m depth). Results indicate an apparently linear dependence of fracture toughness on porosity such that Kinit = 0.257 ρ-80.7, predicting a zero-porosity toughness of Ko = 155 kPa m1/2. We have used this data to test the applicability to crevassing of a two-dimensional fracture mechanics criterion for the propagation of a small sharp crack in a biaxial stress field. The growth of an initial flaw into a larger crevasse, which involves a purely tensile crack opening, depends on the size of the flaw, the magnitude of Kinit and the nature of the applied stress field. By incorporating the criterion into a stress map of the Filchner-Ronne Ice Shelf derived from a depth-integrated finite element model of the strain-rate field, we have been able to predict regions of potential crevassing. These agree well with satellite imagery provided an initial flaw size is assumed in the range 5–50 cm.