The contribution of radar interferometry to the assessment of landslide hazards

Interferometric analysis of repeat pass radar images (InSAR) enables the mapping of slope movements with high accuracy, being of great relevance for the assessment of landslide risk. The InSAR method is briefly explained, with emphasis on data processing for landslide motion mapping. Constraints of the method are discussed, mainly resulting from temporal decorrelation of the radar signal in vegetated areas. Application examples for InSAR mapping of very slow slope movements, using SAR data of the European Earth Observation Satellite ERS, are shown for a mass waste above an alpine traffic route and for slope deformation in a mountain village. The comparison with GPS measurements of surface motion shows RMSE = 3.7 mm a⁻¹ between the InSAR and GPS retrieved motion, where part of this difference is attributed to the different observation periods. The investigations demonstrate the good capability of InSAR for detecting and monitoring surface deformation on mountain slopes, thus providing valuable support for landslide inventories and risk assessment.