Landslide Monitoring Using Radar Interferometry in the Alps

Active natural processes, such as landslides, that can induce damages and casualties, recurrently affect mountainous areas. In order to reduce the risks, the careful assessment and monitoring of landslides is highly needed. Interferometric Synthetic Aperture Radar (InSAR) is a powerful tool that can extract useful information to monitor natural hazards. Over the past two decades, several studies have demonstrated the potential of synthetic aperture radar interferometry for detecting and quantifying land surface deformation. Despite the advantages of InSAR methods for quantifying landslide deformation, some limitations remain. The temporal and spatial decorrelation, the presence of atmospheric artifacts, the 1-D Line Of Sight (LOS) observation restriction, the possible high velocity rate and the multi-directional movement properties make it difficult to monitor accurately complex landslides in areas covered by vegetation. Therefore, complementary and integrated approaches, such as offset tracking-based techniques, and sophisticated atmospheric artifacts estimation are needed to overcome these limitations for monitoring ground surface deformations. These critical issues are particularly challenging in mountain environments, due to the SAR properties, the stronger spatial variations of the local atmospheric conditions and the scattering characteristics of the ground surface, leading to spatial and temporal decorrelation of the SAR signal. Hence, the performance evaluation of the offset tracking and atmospheric corrections techniques is important in order to assess their potentials, robustness and limitations. In this thesis, we aim at improving estimation accuracy of offset tracking and InSAR atmospheric phase delay estimation. To this end, the Corvara landslide, located in the Alpine region of South Tyrol, is used as a pilot site to implement and test the offset tracking and atmospheric correction techniques. This area is monitored with GPS periodic campaigns and permanent stations and over there a set of corner reflectors have been installed.