Integrating InSAR into engineering geological practice: Insights from urban excavation and slope failure

Satellite Interferometric Synthetic Aperture Radar (InSAR) is increasingly being integrated into the engineering geology workflow for infrastructure projects, providing spatially continuous ground deformation measurements across wide areas. This presentation demonstrates the power of InSAR through two contrasting Italian case studies.

The first examines the January 2026 Niscemi landslide, where long-term satellite archives reveal regional deformation patterns and short-term datasets capture the acceleration preceding failure. By analysing all spatial scales, the temporal evolution of instability is reconstructed. InSAR uniquely delivers retrospective, quantitative measurements of historical ground behaviour, providing critical insight into legacy deformation patterns.

The second case study covers excavations of the Milan Metro Line 4 (2019–2021), where InSAR characterises pre-construction conditions and detects millimetre-scale subsidence during tunnelling beneath a dense urban centre. The study illustrates the advantages of consistent, wide-area satellite monitoring for measuring and contextualising ground movements across complex urban settings.

Together, these examples demonstrate how InSAR complements investigation and modelling, enabling evidence-based decision-making in challenging engineering settings.