InSAR techniques and applications for monitoring landslides and subsidence

Interferometric synthetic aperture radar (InSAR) methods and applications for mapping and monitoring displacements on mountain slopes and subsidence in urban areas were investigated in the EC project MUSCL (Monitoring Urban Subsidence, Cavities and Landslides by means of remote sensing) using various techniques. The area-extended differential InSAR technique was applied for mapping slow slope movements in Alpine areas, based on interferograms over annual time spans derived from ERS repeat pass SAR data. The Permanent Scatterer technique, using long time series of SAR data, was applied to map ground deformation at millimetric accuracy. The PS technique is based on dense grids of stable radar targets, enabling the correction of atmospheric noise and the measurement of motion at the scale of individual pixels. An example is shown for motion analysis of a landslide in the Italian Alps. The application of ground-based InSAR was investigated at a rockfall area in the Austrian Alps, revealing a complex deformation pattern. This technique offers flexibility in terms of observation geometry and enables continuous monitoring, making it an excellent tool for emergency cases. The investigations demonstrate the power and complementarity of various InSAR methods for detecting and monitoring hazardous mass wastes.