On the Mechanics of Surging Glaciers

摘要: Observations of surging glaciers indicate that the flow regime is one dominated by extensional flow. The stress state has substantial longitudinal deviatoric stress. This very different from conventional model for glacier dynamics which shearing In addition, initiation often involves a compression front travels down glacier. seems to divide an up-stream region high drag at base low allows rapid sliding. We develop framework mechanics undergoing surging. Relevant issues are and flows, stress, near basal discontinuity. find some down-slope component weight borne in rapidly sliding region. thrusts against slowly moving parts hypothesize this effect causes part spread travel A criterion spreading developed. outlined above used highly idealized propose regions relatively common features glaciers. surge initiates when conditions met allow nucleus spread. spreads large Surging ends low-drag terminate. Because changed glacier, nuclei now stable spreading. Several years rebuilding must occur before once more unstable. Calculations performed evolution shape Medvezhy Glacier during 1963. remarkable similarity between data our computations.