An investigation into the forces that drive ice-shelf rift propagation on the Amery Ice Shelf, East Antarctica

• Published in: Journal of glaciology Vol. 54; no. 184; pp. 17 - 27
• Main Authors: Bassis, Jeremy N., Fricker, Helen A., Coleman, Richard, Minster, Jean-Bernard
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 2008; International Glaciological Society
• Subjects: Earth, ocean, space; Exact sciences and technology; External geophysics; Snow. Ice. Glaciers; polar regions; Antarctica; East Antarctica; Antarctica, MacRobertson Land, Amery Ice Shelf; PSE, Antarctica, MacRobertson Land, Amery Ice Shelf; PSE, Antarctica, East Antarctica; Antarctica, East Antarctica; Fracture mechanics; Wind velocity; Environmental factor; Wind effect; Measurement campaign; swells; Crack propagation; Global Positioning System; Tide effect; seismometers; Ice shelf; Observation data; Polar region; Triggering; Ice calving
• ISSN: 0022-1430; 1727-5652
• DOI: 10.3189/002214308784409116

For three field seasons (2002/03, 2004/05, 2005/06) we have deployed a network of GPS receivers and seismometers around the tip of a propagating rift on the Amery Ice Shelf, East Antarctica. During these campaigns we detected seven bursts of episodic rift propagation. To determine whether these rift propagation events were triggered by short-term environmental forcings, we analyzed simultaneous ancillary data such as wind speeds, tidal amplitudes and sea-ice fraction (a proxy variable for ocean swell). We find that none of these environmental forcings, separately or together, correlated with rift propagation. This apparent insensitivity of ice-shelf rift propagation to short-term environmental forcings leads us to suggest that the rifting process is primarily driven by the internal glaciological stress. Our hypothesis is supported by order-of-magnitude calculations that the glaciological stress is the dominant term in the force balance. However, our calculations also indicate that as the ice shelf thins or the rift system matures and iceberg detachment becomes imminent, short-term stresses due to winds and ocean swell may become more important.