Sudden increase in tidal response linked to calving and acceleration at a large Greenland outlet glacier

• Published in: Geophysical Research Letters
• Main Authors: de Juan, Julia, Elósegui, Pedro, Nettles, Meredith, Larsen, Tine B., Davis, James L., Hamilton, Gordon S., Stearns, Leigh A., Andersen, Morten L., Ekström, Göran, Ahlstrøm, Andreas P., Stenseng, Lars, Khan, Shfaqat Abbas, Forsberg, René
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2010
• Subjects: glacier; Greenland
• Online Access: https://orbit.dtu.dk/en/publications/b82eb766-fa63-476b-a245-f0ba18290864; https://doi.org/10.1029/2010GL043289

Large calving events at Greenland's largest outlet glaciers are associated with glacial earthquakes and near-instantaneous increases in glacier flow speed. At some glaciers and ice streams, flow is also modulated in a regular way by ocean tidal forcing at the terminus. At Helheim Glacier, analysis of geodetic data shows decimeter-level periodic position variations in response to tidal forcing. However, we also observe transient increases of more than 100% in the glacier's responsiveness to such tidal forcing following glacial-earthquake calving events. The timing and amplitude of the changes correlate strongly with the step-like increases in glacier speed and longitudinal strain rate associated with glacial earthquakes. The enhanced response to the ocean tides may be explained by a temporary disruption of the subglacial drainage system and a concomitant reduction of the friction at the ice-bedrock interface, and suggests a new means by which geodetic data may be used to infer glacier properties.