Use of Permanent Scatterers Technique for large scale mass movement investigation

In the Oltrepo Pavese (Northern Italy), several areas subjected to risk assessment according to Italian law are located around a highly fractured sandstone slabs (M. Vallassa Sandstone) lying on a deformable clayey substratum (Epiligurian Sequence). The structural and geomorphologic surveys and comparison with results obtained by some authors in similar geological contexts indicate the possible presence of deep-seated gravitational deformations, which could be classified as lateral spread. The potentiality of the Permanent Scatterers technique has been explored by the authors for investigating large slope displacements in the Oltrepo Pavese. The Permanent Scatterers analysis was combined with in situ conventional geomorphological, structural and geotechnical studies. Test sites, corresponding to sandstone slabs and areas classified at high risk from the institutional authorities, were selected. A geological model of each test area was obtained from the integration of the geological–geomorphological character of the site with the geotechnical data (boreholes, piezometers and laboratory tests). The PS technique allows to detect and delimit the unstable area and to identify some zones within the mass movement characterized by different displacements rates, and thus different degree of hazard.