Detecting site instability hazards with SAR interferometry

摘要

The advanced multi-temporal Differential Synthetic Aperture Radar Interferometry (DInSAR) methods e.g. Permanent Scatterers Interferometry (PSIn-SAR), mitigate the limitations of conventional DInSAR and extend the applicability of radar interferometry from wide-area, regional-scale detection and monitoring of ground surface deformations to local-scale engineering geology investigations of site instability linked to settlements and/or deterioration of engineering structures. Since the presence of movements can be taken as a direct evidence of potential failure hazard, PSInSAR can be used to provide a preliminary distinction of conditions of relative stability or instability. Furthermore, thanks to a regular re-visit schedule of the radar satellites and the millimetric precision of measurements, a long-term monitoring of small displacements is feasible. To show the practical applicability of PSInSAR in site instability investigations we present two examples from Italy's capital, which reveal (ⅰ) presence of local subsidence (settlements) in areas of the old Rome underlain by the Holocene age alluvial deposits of the Tiber River and (ⅱ) very local site instability (or monument deterioration) in the Imperial Forum area (ancient Rome).