Tracking the Cracking: A Holistic Analysis of Rapid Ice Shelf Fracture Using Seismology, Geodesy, and Satellite Imagery on the Pine Island Glacier Ice Shelf, West Antarctica

Ice shelves regulate the stability of marine ice sheets. We track fractures on Pine Island Glacier, a quickly accelerating glacier in West Antarctica that contributes more to sea level rise than any other glacier. Using an on-ice seismic network deployed from 2012 to 2014, we catalog icequakes that dominantly consist of flexural gravity waves. Icequakes occur near the rift tip and in two distinct areas of the shear margin, and TerraSAR-X imagery shows significant fracture in each source region. Rift-tip icequakes increase with ice speed, linking rift fracture to glaciological stresses and/or localized thinning. Using a simple flexural gravity wave model, we deconvolve wave propagation effects to estimate icequake source durations of 19.5-50.0 s and transient loads of 3.8-14.0 kPa corresponding to 4.3-15.9 m of crevasse growth per icequake. These long-source durations suggest that water flow may limit the rate of crevasse opening.

Automated summary

Ice shelves play an important role in maintaining the stability of marine ice sheets. A study on Pine Island Glacier in West Antarctica reveals that fractures on the glacier are mainly caused by flexural gravity waves. The occurrences of icequakes near the rift tip and shear margin suggest a connection with glaciological stresses and/or localized thinning. Analysis using a flexural gravity wave model estimates that each icequake results in crevasse growth of 4.3-15.9 meters, and water flow may limit the opening rate of the fractures.