Sentinel-1 PSI Data for the Evaluation of Landslide Geohazard and Impact

In this work we exploited Sentinel-1 satellite radar images processed by means of Persistent Scatterers Interferometry (PSI) techniques for the evaluation of landslide geohazard and impact on a mountainous region. In particular, we used PSI data as starting point in a working chain whose final goal is the estimation of the potential worth of loss of the structures involved by slope instability phenomena. We applied this approach on a test area in the Valle d’Aosta Region (North Italy) where more than fifty percent of the territory is above 2000 m a.s.l. and extensively affected by landslides. Firstly, PSI Sentinel-1 data permitted to scan the territory and to highlight the areas characterized by the highest ground motion rates, namely Active Deformation Areas (ADA). These areas were used to derive the intensity of potential landslides in terms of magnitude. Then, for the different elements at risk (EAR) we estimated both the vulnerability, by referring to values already proposed in literature for similar working scale, and the exposure, by considering the current real estate market values of the EAR in the area. We finally derived color-scale maps showing landslide intensity and values of potential loss expressed in quantitative terms (Euros for square meters). This operational methodology can provide useful indications and outputs for landslide risk management at regional scale. Considering the present availability of Sentinel-1 SAR images with 6-days revisiting time, this procedure can represent an example of satellite InSAR monitoring as supporting tool for Civil Protection activities and geohazard mitigation long-term strategies.