Deformation monitoring over large areas with multipass differential SAR interferometry: a new approach based on the use of spatial differences

Multipass differential synthetic aperture radar interferometry is becoming increasingly important as a powerful technique for ground deformation retrieval compared with classical geodetic techniques such as levelling and global positioning system (GPS). It proves superior in terms of costs, coverage, data accessibility and availability of historical archives. Application to different areas of risk management such as monitoring of volcanoes and slope instabilities, tectonic movements, urban areas and infrastructure, has already been successfully demonstrated. In this work we discuss a new multipass differential synthetic aperture radar interferometry processing technique that makes extensive use of spatial differences. The results obtained demonstrate that this technique allows the monitoring of ground deformation over wide areas. The processed data were acquired from ERS-1 and ERS-2 sensors over three partially overlapping tracks related to a region, approximately 240km N-S and 80km E-W wide, located in the centre-south of Italy, along the west coast. Comparison of the mean deformation velocity results over the different tracks and of the deformation evolution with levelling measures, available in some areas, shows good agreement and goes to validate the technique.