Surge

Surge

Surge refers to a sudden and temporary increase in the velocity of a glacier, caused by an increase in basal water pressure, resulting in a wave of ice moving downglacier at a speed of 4-7 km/year. During the surge phase, there is an intense collision and compression of ice bodies, which leads to the drainage of part of the basal meltwater in early summer, causing the glacier to decelerate correspondingly.From: Geomorphology [2019], A holistic view of Shisper Glacier surge and outburst floods: from physical processes to downstream impacts [2021]

The glacier sedimentary system

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Published in Richard J. Chorley, Stanley A. Schumm, David E. Sugden, Geomorphology, 2019

Richard J. Chorley, Stanley A. Schumm, David E. Sugden

A few glaciers flow at speeds an order of magnitude higher than these figures. For example, Jakobshavn, Isbrae, one of the largest outlet glaciers in Greenland, flows at 7–12 km/year. Also there are a number of glaciers which experience periodic surges in which a wave of ice moves downglacier at velocities of 4–7 km/year. In these cases the surging ice velocities may be 10–100 times greater than the previous velocity. Further, the jump from normal to surging velocities takes place very suddenly.

A holistic view of Shisper Glacier surge and outburst floods: from physical processes to downstream impacts

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Published in Geomatics, Natural Hazards and Risk, 2021

Sher Muhammad, Jia Li, Jakob F. Steiner, Finu Shrestha, Ghulam M. Shah, Etienne Berthier, Lei Guo, Li-xin Wu, Lide Tian

In general, both Sentinel-2 and Sentinel-1 flow velocity results show that the Shisper Glacier accelerated in winter/spring and decelerated in summer, which is a typical feature of hydrologically-controlled glacier surge (Kamb 1987; Round et al., 2017). It is likely that the basal water pressure increased in winter/spring and promoted the glacier acceleration; however, as the collision and compression of ice bodies intensified during the surge phase, part of the basal meltwater drained in early summer and the glacier decelerated correspondingly. Hence, the Shisper Glacier may surge again in the coming decades. To some extent, no matter how much mass the Shisper Glacier accumulates at its upper reaches, it will surge as long as its basal water pressure is high enough.

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The glacier sedimentary system

A holistic view of Shisper Glacier surge and outburst floods: from physical processes to downstream impacts