Monitoring Subsidence and Building Vulnerability in Como, Italy: 30 Years of InSAR

Urban areas built on alluvial and lacustrine deposits in low-lying, coastal, and delta regions are increasingly exposed to geohazards such as subsidence, driven by both natural processes and human activity, and further intensified by climate change. This study presents a synthesis of 30 years (1993–2023) of satellite-based ground deformation monitoring in the city of Como (Northern Italy), integrating multi-sensor Interferometric Synthetic Aperture Radar (InSAR) data with building damage surveys conducted in 2019 and geological–stratigraphic data. The analysis adopts a multi-scale and multi-temporal approach, combining long-term C-band observations (ERS-1/2, Envisat, Sentinel-1) with high-resolution X-band Cosmo-SkyMed data at the building scale. The investigation reveals prolonged deformation patterns in specific sectors of the city, correlated with known fill areas, historical drainage basins, and low-lying zones. Damaged buildings are predominantly concentrated in the historic city centre, where cumulative vertical displacements exceeded 10 mm in the years leading up to 2019, thus suggesting the presence of measurable pre-failure signals. This work highlights the value of long-term, satellite-based deformation monitoring as a practical decision-support tool for engineering geologists and urban planners in geologically sensitive urban environments. We also discuss implications for early-warning systems, urban resilience planning, and future monitoring strategies.