The Engineering Geology Hazards of Rock Glaciers

Abstract

Rock glaciers are common, yet, because of the association with past periglacial and glacial activity, are often ignored as present day engineering hazards. As alpine development increases, rock glacier location and analysis becomes vital. Air and ground reconnaissance easily identifies rock glaciers using four characteristics: 1) slope angle somewhere between that of the adjoining rock face and the valley floor below; 2) surface of coarse rock fragments; 3) little or no surface vegetation; and 4) concave-upward slope profiles in the upper parts and strongly convex fronts. Active rock glaciers are best avoided because of rock glacier movement and ice melting and subsidence. Inactive rock glaciers may be built on or excavated depending on the presence of clear ice layers in the rock glacier and the amount of risk engineers are willing to assume. On inactive rock glaciers containing only interstitial ice, permafrost construction techniques may be effective.