Glacier-Induced Hazards as a Consequence of Glacigenic Mountain Landscapes, in Particular Glacier- and Moraine-Dammed Lake Outbursts and Holocene Debris Production

Abstract

With the help of representative examples this paper attempts to infer the damaging effects, induced by glaciers, not only — as is normally the case (cf. amongst others, Hewitt 1982, 1988, 1995) — from the geomorphodynamics, observed directly on the spot, but from the entire glacigenic character of the high mountain landscape. Accordingly, not only the current changes of the glacier, which produce damage — as for instance the shifting of the glacier termination (cf. 3.) — are on the focus of interest, but also the development of the glacigenic relief during the High- to Late Glacial (cf. 2.). From the mountain shaping through prehistorical glaciation, partly filling up the relief, a transformation of the valleys resulted, which was not stable during the Interglacials. Characteristics of the glacial relief, such as U-shaped valleys, subsequently crumbled away on their typically over-steepened valley flanks and collapsed as soon as, following deglaciation, the abutment of the ice filling was absent in the valley. This is a process which, in the Interglacials, the preglacial U-shaped valley relief — depending on the length of time passed since deglaciation and according to resistance of the valley flanks — more or less quickly reestablishes. Through the processes proceeding as a result, i.e. wet and dry mass self-movements such as rockfall, rock slide, landslide etc., debris bodies are built up on the valley floors. These directly or indirectly result in or induce in the form of fans, cones and screes numerous damaging effects (cf. 4.).