FRACTURE-MECHANICS APPROACH TO PENETRATION OF BOTTOM CREVASSES ON GLACIERS

A simple model, based on linear elastic fracture mechanics, is used to investigate conditions allowing the existence of bottom crevasses. On grounded glaciers, these crevasses can only occur if the basal water pressure is close to the ice overburden pressure. If the piezometric h ead drops more than similar to 10 m below the flotation level, very la rge stretching rates are required for appreciable bottom crevasses to form. This combination of special conditions may explain the lack of o bservations of basal crevassing on grounded glaciers. (C) 1998 Elsevie r Science B.V. All rights reserved.