Il telerilevamento satellitare per la valutazione dei rischi geologici lungo le infrastrutture lineari

The linear infrastructures can extend their routes for several hundred kilometres, crossing geologically complex areas. For this reason, during the design phase of a linear infrastructure, but also during the construction itself, a careful analysis of geological risk variables (geohazard) must be conducted. Furthermore, attention should be focused to the possible interactions that the structure itself could have with the surrounding area. The need for effective and rapid solutions for the analysis and monitoring of geological phenomena can find a valid answer in the application of modern remote sensing techniques. In the last decades, spaceborne radar differential interferometry or D-InSAR (Differential Interferometric Synthetic Aperture Radar) is one of the most used techniques used for the identification, and measurement, of Earth's surface deformations produced by natural or anthropic events. Since the launch of the Sentinel-1 missions (ESA), the use of radar data has moved from purely research purposes, to more applied uses, like the identification and monitoring of natural hazards, supporting conventional techniques. In this thesis, the theory fundamentals and the main uses of InSAR applied to the analysis of geological risks are introduced, together with the most used and recent techniques. This is accomplished through the presentation of some real case studies, which present, more or less directly, affinity with some of the geological problems that could be addressed during the design, construction or operation of a linear infrastructure. The first part is dedicated to the use of InSAR for the analysis of ground displacements produced by strong seismic events and active tectonics. Some field-validated methodologies for detecting coseismic fractures through D-InSAR techniques are presented. In addition, some results relating to multi-temporal analyses for the identification of aseismic deformations are shown. The second part deals with the use of satellite SAR remote sensing for monitoring the settlements induced by underground tunnelling on the environment and surrounding structures. This in order both to exclude possible previous deformations, and to monitor, or to evaluate, what may have been, for example, the actual induced subsidence. In the last part of the thesis, the performances on the use of interferometric techniques for the characterization of landslides and for the preliminary screening of landslide treat over large areas are assessed. A method to deal with lack of ground reflectors in rural areas is tested and validated. The critical evaluation of the results obtained in the various applications confirms, and highlights, the expectations related to the potential of SAR data for the rapid assessment of geological risks along linear infrastructures. The application limits are also described. InSAR confirms his role as a promising technology that could find application at every stage of a project, from feasibility analysis to decommissioning.