InSAR for mapping ground deformation
Interferometric Synthetic Aperture Radar (InSAR) is a satellite-based technique used to measure ground deformation by comparing radar images acquired at different times. It enables precise monitoring of surface motion with millimetre-scale accuracy, independent of weather conditions or daylight.
Method and applications
InSAR is based on the analysis of phase differences between two or more Synthetic Aperture Radar (SAR) images, which are generated by active radar sensors transmitting and receiving microwave signals reflected from the Earth’s surface. Because SAR signals can penetrate clouds and operate day and night, InSAR provides reliable, continuous observations over large areas. Surface displacement is inferred from changes in the radar signal phase between repeated acquisitions, allowing relative ground motion to be mapped with high precision.
Data from missions such as ESA’s Sentinel-1 enable systematic monitoring of processes including landslides, glacier flow, subsidence, and tectonic deformation. In rapidly changing environments, complementary techniques such as offset (feature) tracking are often used to derive surface velocities, particularly over glaciers and ice sheets in polar regions.