This article highlights the influence of surface meltwater and tides on crevasse opening leading to major calving events at grounded tidewater glaciers, such as Bowdoin Glacier, Northwest Greenland, where most calving occurs by a few large events resulting from kilometre-scale fractures forming parallel to the calving front. High-resolution terrestrial radar interferometry data of such an event reveal that crevasse opening is fastest at low tide and accelerates during the final 36 h before calving. Using  Elmer/Ice, the authors identify the crevasse water level as a key driver of modelled opening rates. Sea water-level variations in the range of local tidal amplitude (1 m) can reproduce observed opening rate fluctuations, provided crevasse water level is at least 4 m above the low-tide sea level. The accelerated opening rates within the final 36 h before calving can be modelled by additional meltwater input into the crevasse, enhanced ice cliff undercutting by submarine melt, ice damage increase due to tidal cyclic fatigue, crevasse deepening or a combination of all these processes.

Read more: van Dongen E.,G. Jouvet,A. Walter,J. Todd,T. Zwinger,I. Asaji,S. Sugiyama, F. Walter and M. Funk, 2019. Tides modulate crevasse opening prior to a major calving event at Bowdoin Glacier, Northwest Greenland. Journal of Glaciology 1–11, DOI: 10.1017/jog.2019.89.