The variability of tidewater-glacier calving: origin of event-size and interval distributions

• Published in: Journal of Glaciology
• Main Authors: CHAPUIS, Anne, Tetzlaff, Tom
• Format: Article in Journal/Newspaper
• Language: English
• Published: Soc. 2014
• Subjects: info:eu-repo/classification/ddc/550; glacier; Journal of Glaciology; Svalbard; Tidewater
• Online Access: https://juser.fz-juelich.de/record/155279; https://juser.fz-juelich.de/search?p=id:%22FZJ-2014-04452%22

Calving activity at the termini of tidewater glaciers produces a wide range of iceberg sizes atirregular intervals. We present calving-event data obtained from continuous observations of the terminiof two tidewater glaciers on Svalbard, and show that the distributions of event sizes and inter-eventintervals can be reproduced by a simple calving model, focusing on the mutual interplay between calvingand the destabilization of the glacier terminus. The event-size distributions of both the field and themodel data extend over several orders of magnitude and resemble power laws. The distributions of intereventintervals are broad, but have a less pronounced tail. In the model, the width of the size distributionincreases with the calving susceptibility of the glacier terminus, a parameter measuring the effect ofcalving on the stress in the local neighborhood of the calving region. Inter-event interval distributions, incontrast, are insensitive to the calving susceptibility. Above a critical susceptibility, small perturbations ofthe glacier result in ongoing self-sustained calving activity. The model suggests that the shape of theevent-size distribution of a glacier is informative about its proximity to this transition point. Observationsof rapid glacier retreats can be explained by supercritical self-sustained calving.