Kinematic investigations on the Furggwanghorn Rock Glacier, Switzerland

Many thermo-hydro-mechanical parameters and their interactions influence the creep behaviour of rock glaciers, with the result that the kinematics of rock glaciers are complex and not fully understood. An interdisciplinary project began in 2010 to investigate the physical ground conditions and any climatic dependence of a fast-moving rock glacier below the Furggwanghorn peak, in the Turtmann Valley of the Swiss Alps. Remote sensing and subsurface instrumentation (in-place inclinometers and temperature sensors), together with ground and airborne geophysical methods, reveal the creep rate and the hydrological and thermal conditions of the rock glacier. The Furggwanghorn rock glacier exhibits displacements in the order of metres per year and showed substantial surface changes at a minimal ground temperature slightly below 0 degrees C. A detailed three-dimensional kinematic ground model shows the internal structure and shear surfaces, indicating past creep behaviour and failure mechanisms. The results suggest that observed seasonal changes in the creep rate of the rock glacier did not depend directly on the temperature at depth, but were very likely controlled by hydrological processes.