Monitoring Landslide-Induced Displacements with TerraSAR-X Persistent Scatterer Interferometry (PSI): Gimigliano Case Study in Calabria Region (Italy)

Abstract

This work provides a detailed detection of landslide-induced displacements at local scale on Gimigliano site (Italy), by means of PSI (Persistent Scatterers Interferometry) analysis, exploiting TerraSAR-X data acquired in November 2010-October 2011. In February-March 2010, several landslides affected Gimigliano, following high-intensity precipitation, and causing damages to structures and roads. In order to assess any spatial and temporal patterns of deformation, the present X-band PS data were compared with historical motion rates derived from ERS1/2 and ENVISAT satellites, and with geological and geomorphological evidences resulting from auxiliary data such as landslide databases and orthophotos referred to different dates, finally validated with recent field checks. The PSI analysis of the historical ground motion rates highlighted that the modern built-up area located downhill was already affected by surface ground deformation since 1993. A significant enlargement of the instability phenomena is detected across time. The recent PS data analysis and the in situ observations permitted us to accurately update the ground movements in the investigated site: their evidence allowed assessing a reactivation of the large deep-seated landslide zone on which the new urbanized area had built-up, with an average deformation rate of about 8 - 9 mm/yr. The higher instability phenomenon is affecting the eastern part of Gimigliano old village, with a mean displacement velocity reaching up values of -30 mm/yr, in the radar temporal acquisition of only 10 months. These outcomes can be taken into account for further hazard-reduction analysis and to support risk mitigation design within the investigated area.