Glacier surges are periodic episodes of mass redistribution characterized by dramatic increases in ice flow velocity and, sometimes, terminus advance. We use optical satellite imagery to document five previously unexamined surge events of Sít’ Kusá (Turner Glacier) in the St. Elias Mountains of Alaska from 1983 to 2013. Surge events had an average recurrence interval of ~5 years, making it the shortest known regular recurrence interval in the world. Surge events appear to initiate in the winter, with speeds reaching up to ~25 m d−1. The surges propagate down-glacier over ~2 years, resulting in maximum thinning of ~100 m in the reservoir zone and comparable thickening at the terminus. Collectively, the rapid recurrence interval, winter initiation and down-glacier propagation suggest Sít’ Kusá's surges are driven by periodic changes in subglacial hydrology and glacier sliding. Elevation change observations from the northern tributary show a kinematic disconnect above and below an icefall located 23 km from the terminus. We suggest the kinematic disconnect inhibits drawdown from the accumulation zone above the icefall, which leads to a steady flux of ice into the reservoir zone, and contributes to the glacier's exceptionally short recurrence interval.
Bibliographical noteFunding Information:
A.N. was supported by the Maine Space Grant Consortium and the Golden Fund. A.N. acknowledges support provided by WestGrid ( www.westgrid.ca ) and Compute Canada Calcul Canada ( www.computecanada.ca ). W.K. was supported by the National Science Foundation Graduate Research Fellowship under grant No. DGE-1144205. R.M. acknowledges support from the European Space Agency through Glaciers_CCI and CCI+ (4000109873/14/I-NB, 4000127593/19/I-NS), and by the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC grant agreement No. 320816. WorldView imagery and DEMs were provided by the Polar Geospatial Center under NSF-OPP awards 1043681, 1559691 and 1542736. A.N. and W.K. thank the Explorers Club and Geologic Society of America for providing funding for a 2018 field season. K.K. was supported by NSF-AGS award 1502783. We thank Hester Jiskoot for her helpful conversations about surging that informed this manuscript through the RemoteEx partnership exchange program, funded by the Norwegian Agency for International Cooperation and Quality Enhancement in Higher Education and in her capacity as Chief Editor. We also thank Scientific Editor Shad O'Neel, William Armstrong and two anonymous reviewers for constructive feedback which helped improve the quality of the manuscript. Finally, we would like to acknowledge the Yakutat Tlingit Tribe on whose land Sít’ Kusá lies.
Copyright © The Author(s), 2021. Published by Cambridge University Press.
- Glacier surges
- glacier hazards
- remote sensing