A damage mechanics assessment of the Larsen B ice shelf prior to collapse: Toward a physically‐based calving law

• Published in: Geophysical Research Letters
• Main Authors: Borstad, CP, Khazendar, A, Larour, E, Morlighem, M, Rignot, E, Schodlok, MP, Seroussi, H
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: eScholarship, University of California 2012
• Subjects: Meteorology & Atmospheric Sciences; Ice Sheet; Ice Shelf
• Online Access: https://escholarship.org/uc/item/95v6k9p4; https://escholarship.org/content/qt95v6k9p4/qt95v6k9p4.pdf; https://doi.org/10.1029/2012gl053317

Calving is a primary process of mass ablation for glaciers and ice sheets, though it still eludes a general physical law. Here, we propose a calving framework based on continuum damage mechanics coupled with the equations of viscous deformation of glacier ice. We introduce a scalar damage variable that quantifies the loss of load-bearing surface area due to fractures and that feeds back with ice viscosity to represent fracture-induced softening. The calving law is a standard failure criterion for viscous damaging materials and represents a macroscopic brittle instability quantified by a critical or threshold damage. We constrain this threshold using the Ice Sheet System Model (ISSM) by inverting for damage on the Larsen B ice shelf prior to its 2002 collapse. By analyzing the damage distribution in areas that subsequently calved, we conclude that calving occurs after fractures have reduced the load-bearing capacity of the ice by 60 ± 10%. © 2012. American Geophysical Union. All Rights Reserved.