Crevasse initiation and history within the McMurdo Shear Zone, Antarctica

• Published in: Journal of Glaciology
• Main Authors: Lynn Kaluzienski, Peter Koons, Ellyn Enderlin, Gordon Hamilton, Zoe Courville, Steven Arcone
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2019
• Subjects: Crevasses; ice shelves; ground-penetrating radar; ice velocity; Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; Antarc*; Antarctica; Ice Shelves; Journal of Glaciology
• Online Access: https://doi.org/10.1017/jog.2019.65; https://doaj.org/article/fbb285d6042f480b9ebc6d71de6d5923

While large-scale observations of intensified fracture and rifting can be observed through remote-sensing observations, understanding crevasse initiation may best be achieved with small-scale observations in which crevasses can be directly observed. Here we investigate the kinematic drivers of crevasse initiation in the McMurdo Shear Zone (MSZ), Antarctica. We delineated 420 crevasses from ~95 km of 400 MHz frequency ground-penetrating radar data and compared these data with kinematic outputs derived from remotely-sensed ice surface velocities to develop a statistical method to estimate crevasse initiation threshold strain rate values. We found the MSZ to be dominated by simple shear and that surface shear strain rates proved best for predicting crevasse features, with regions of higher shear strain rate more likely to have a greater number of crevasses. In the surveyed portion of our study region, values of shear strain rate and vorticity rate derived from the MEaSUREs2 velocity dataset range between 0.005–0.020 and 0.006–0.022 a−1, respectively, with crevasses located at ≥0.011 and ≥0.013 a−1. While threshold values from this study cannot be directly applied to other glacial environments, the method described here should allow for the study of shear margin evolution and assessment of localized damage and weakening processes in other locations where in situ data are available.