InSARmonitoring

InSAR monitoring, short for interferometric synthetic aperture radar monitoring, is a remote sensing technique that measures ground deformation by analyzing the phase difference between radar echoes acquired by satellites during successive passes. By comparing complex radar images, it reveals line-of-sight displacement with spatially dense coverage over large areas. Time-series variants of InSAR extend this capability to track deformation continuously over days to years.

Different methods exist within InSAR monitoring. Differential InSAR (DInSAR) compares pairs of acquisitions to produce a deformation map for a specific time interval. Time-series approaches such as Persistent Scatterer Interferometry (PSInSAR) and Small Baseline Subset (SBAS) extract displacement signals over many acquisitions, mitigate atmospheric and orbital noise, and generate displacement time series and velocity maps. The results are typically expressed as deformation along the radar line of sight, which can be combined with multiple viewing geometries to estimate other components of motion.

Data sources include a range of SAR satellites, notably Sentinel-1, TerraSAR-X, Cosmo-SkyMed, and RADARSAT missions. Outputs of InSAR monitoring are deformation maps, velocity maps, and time-series plots that can be integrated into GIS for visualization and analysis. Common applications span geohazards and engineering, including subsidence from groundwater or mining, volcano inflation or eruption precursors, earthquake faulting, landslide monitoring, and structural health assessment of dams, bridges, and tunnels.

Limitations include decorrelation in vegetated or rapidly changing areas, atmospheric phase delays, thermal noise, and operational constraints such as revisit times and orbital geometries. Despite these challenges, InSAR monitoring provides a valuable, repeatable, high-resolution view of surface deformation over large areas.