Monitoring very slow slope movements by means of SAR interferometry: A case study from a mass waste above a reservoir in the Otztal Alps, Austria

The application of radar interferometry to detect slope movements on the or der of millimeters to centimeters per year is demonstrated. The deformation field of a slope above a hydropower reservoir in the Austrian Alps was der ived from SAR interferometric pairs of the satellites ERS-1 and ERS-2 acqui red between July 1992 and August 1998. Above the treeline it was possible t o map the motion from interferograms covering time spans up to three years. Whereas ground-based geodetic measurements focussed on the movements of th e lower slope section, the interferometric analysis shows that the mass was ting processes affect the entire slope of 1000 m vertical extent. Significa nt interannual differences of the displacement rates became apparent which were found to be related to the pattern of summer rainfall.