Velocity and Strain changes on the Larsen C ice shelf prior to a major calving event

On 12th July 2017, the A68 iceberg completely calved away from the Larsen C Ice Shelf on the Antarctic Peninsula. Having experienced some of the warmest temperatures in the polar regions over the previous 3 decades - 3.7 ± 1.6 ◦C (Vaughan et al, 2003), calving becomes more common and increases in surface velocity are often seen as a result of atmospheric warming (Rott et al, 2011; Wuite et al, 2015) and oceanic basal melt (Pritchard et al, 2012). The stability and velocity change as the iceberg is in the process of calving, showing increases in the overall velocity between the 22 SAR image pairs examined. This is followed by velocity decreases in the shelf and inlet glaciers feeding the shelf as the weight of the calving mass disconnects. Strain rates are show to increase, becoming expansive as the calving occurs and remaining compressive after the calving. First order calving remains the dominant method of ice loss (Benn et al, 2007), retaining the shelf’s stability in the form of a compressive arch (Kulessa et al, 2014); unaffected by the calving process and resisting complete shelf disintegration (Borstad et al, 2017). Overall, the ice shelf seems to have remained in a good condition due to buttressing and key pinning points (Rignot et al, 2004), not losing any of its structural integrity and showing that velocity and strain rates derived from satellite imagery can be highly effective due to the improving temporal and spatial capabilities