InSAR Deformation Monitoring in Urban Areas: Analysis at Different Spatial Scales

In recent decades, Interferometric Synthetic Aperture Radar (InSAR), using satellite imagery, has emerged as a powerful tool for ground-deformation monitoring. It brings an advanced, sustainable, and cost-effective solution for long-term monitoring projects on wide areas. Additionally, InSAR can provide historical measurement data, adding further context about past ground-deformation and motion patterns. When using high-resolution sensors, the measurements can achieve millimetric-range deformation precision (1-2 mm) and metric-range geolocation precision (1-2 m) with densities over tens of thousands of measurement points per km². In urban areas, measuring surface motion and ground stability is key, because vulnerability is high due to large population densities and complex land conditions and uses.

The aim of this work is to showcase the applications of InSAR in urban areas at different spatial scales derived using the ATLAS interferometric processing chain, developed by SIXENSE around the core software GAMMA. In this study, the technology will be detailed and several cities over the globe will be presented as examples. Use cases will be provided at three different scopes: the overall city, a district, and a single building. The results will show how a wider view of the metropolitan area allows for the exploration of general motion patterns at a large scale, leveraging the high density and wide coverage of measurements. At a district or neighbourhood scale, areas of active deformation can be identified and monitored, like groups of buildings and roads experiencing subsidence after tunnelling or nearby construction. For the analysis of singular buildings, deformation can be tracked by analysing a time series of point measurements, and surface changes can be identified by loss of phase coherence. Advanced analytics allow us to calculate acceleration, risk of failure, and provide an estimation of the collapse date of structures, which serves as an alert system to anticipate critical events.