Basal crevasses on the Larsen C Ice Shelf, Antarctica: Implications for meltwater ponding and hydrofracture

• Published in: Geophysical Research Letters
• Main Authors: McGrath, D, Steffen, K, Rajaram, H, Scambos, T, Abdalati, W, Rignot, E
• Format: Article in Journal/Newspaper
• Language: English
• Published: eScholarship, University of California 2012
• Subjects: Amery; Cabinet Inlet; Getz; Antarc*; Antarctica; Ice Shelf; Ice Shelves
• Online Access: http://www.escholarship.org/uc/item/9m65b7mc

A key mechanism for the rapid collapse of both the Larsen A and B Ice Shelves was meltwater-driven crevasse propagation. Basal crevasses, large-scale structural features within ice shelves, may have contributed to this mechanism in three important ways: i) the shelf surface deforms due to modified buoyancy and gravitational forces above the basal crevasse, creating >10 m deep compressional surface depressions where meltwater can collect, ii) bending stresses from the modified shape drive surface crevassing, with crevasses reaching 40 m in width, on the flanks of the basal-crevasse-induced trough and iii) the ice thickness is substantially reduced, thereby minimizing the propagation distance before a full-thickness rift is created. We examine a basal crevasse (4.5 km in length, ∼230 m in height), and the corresponding surface features, in the Cabinet Inlet sector of the Larsen C Ice Shelf using a combination of high-resolution (0.5 m) satellite imagery, kinematic GPS and in situ ground penetrating radar. We discuss how basal crevasses may have contributed to the breakup of the Larsen B Ice Shelf by directly controlling the location of meltwater ponding and highlight the presence of similar features on the Amery and Getz Ice Shelves with high-resolution imagery. © 2012. American Geophysical Union. All Rights Reserved.