Satellite radar interferometry for the assessment of ground instability at a cultural heritage site: the case study of Civita di Bagnoregio, Italy|Interferometria radar satellitare per l’analisi della stabilità del terreno su un sito di alto valore per il Patrimonio Culturale: il caso studio di Civita di Bagnoregio, Italia

The town of Civita di Bagnoregio (Central Italy), located at the border of the ancient volcanic complex and placed on a high tuff peak that rests on stiff clay base, represent a site of high cultural-historical value that is linked to the clearly visible effects of the geomorphological evolution of its slopes across time. Multi-temporal satellite SAR interferometry techniques such as PSI (Persistent Scatterers Interferometry) approaches, which analyse long temporal series of SAR images acquired by satellite on the same area in different times, allow accurate measures of terrain displacements on highly reflective radar benchmarks. PSI techniques are remarkably useful over CH (Cultural Heritage) built-areas given their non-invasiveness and high accuracy. Within the Extraordinary Plan for Monitoring and Conservation of Cultural Heritage financed by the national Ministry of Culture since 2022, we exploited X-band high resolution satellite radar interferometric data from the Italian COSMO-SkyMed constellation for detecting and monitoring ground movements over Civita di Bagnoregio site. These data were integrated and cross-compared with cartographic, geomorphological data and location of underground cavities. A good cross-comparison of remotely-sensed ground motion rates with thematic data and with on-site observations was found. Overall, no critical situation arised from the PSI-based results on Civita di Bagnoregio, even if some isolated radar targets show velocity higher than the stable range. Highest ground motion rates could be potentially correlated to the presence of underground cavities that induce instability. The proposed methodology applied to Civita di Bagnoregio enables urban planners, decision-makers, and other stakeholders to better assess hydrogeological ground motion urban sites.