Further Catastrophic Break-Up of a Calving Glacier: Observations at Austerdalsisen, Svartisen, Norway, 1983–87

ABSTRACT

The glacier Austerdalsisen, already subject to break-up by calving, suffered major loss in early summer 1987: almost all the segment of the tongue in the lake Austerdalsvatnet disintegrated. The event probably was triggered by buoyancy forces related to rapid water level change associated with snow melt, but prior fracturing of the tongue was an important factor. As buoyancy forces bent the tongue upwards, bottom crevasses may have linked with fractures which extended down from the glacier surface. Changes of geometry of Austerdalsisen between 1982 and 1987 illustrate the importance of the calving boundary condition in driving glacier flow. Understanding calving is important for management of hydroelectricity power generation schemes, such as those of the Svartisen area, which incorporate glaciers ending in lakes. Several Svartisen glaciers have become much shorter in recent decades as a result of calving.