A PSI-based analysis of landslides in the historic town of Volterra (Italy)

Landslides threaten human lives and structures, especially in urbanized areas, where the density of elements at risk that are sensitive to ground movements is high. Persistent Scatterer Interferometry (PSI) techniques are particularly effective to measure Earth surface displacements for monitoring natural processes just on built-up areas, where many radar benchmarks can be retrieved. This paper aims at detecting terrain motions and their effects on built-up zones, through satellite radar data combined with background data such as aerial imagery and in-situ field surveys on the historic town of Volterra (Tuscany region, Italy). In particular, recent COSMO-SkyMed satellite images acquired in 2010–2015 and processed with SqueeSAR technique permitted to improve the knowledge on mechanisms and spatial distribution of landslide phenomena, as well as to carry out a deformation assessment as a single building-scale analysis. Maximum settlement values of some sample buildings were derived from radar measurements, and then cross-compared with constructive features and with geo-morphological conditions on the known landslide areas, as well as validated with on-field evidences. This work turns out to be useful as a preliminary step for further risk management strategies.