Assessing InSAR observability of landslides interfering with bridges.

Landslides are among the most widespread natural hazards worldwide and a major cause of disruption to infrastructure networks, with significant impacts on safety and territorial resilience. Understanding the conditions under which they can be effectively monitored is crucial for reducing risk and supporting mitigation strategies. Satellite radar interferometry enables the detection of ground deformation with high precision and wide spatial coverage, but the main challenge lies in identifying when this technology can detect and characterise landslides, as radar visibility is strongly influenced by topography and acquisition geometry. This study addresses this challenge by analysing the interferometric observability of landslides near infrastructure, integrating European Ground Motion Service data with the Italian landslide inventory. This combination enables a systematic quantification of how geomorphological factors and movement characteristics influence the radar detectability of landslides interacting with infrastructure. The analysis shows how topographic settings and movement types control radar visibility, and how InSAR can identify activity states and reveal the internal variability of deformation. The comparison between landslides and interfering bridges highlights differences attributable to local conditions, emphasising the importance of interpreting structural deformation within the geomorphological context. The results provide a quantitative basis to guide monitoring strategies and risk management in complex infrastructural settings.