Permanent scatterers in SAR interferometry

Differential SAR interferometry (DInSAR) is an unique tool for low-cost, large-coverage surface deformations monitoring. As well known, the technique involves interferometric phase comparison of SAR images gathered at different times and has the potential to provide millimetric accuracy. Though temporal decorrelation and atmospheric dishomogeneities strongly affect interferogram quality, reliable deformation measurements can be obtained in a multi-image framework on a small subset of image pixels, corresponding to stable areas. These points, hereafter called Permanent Scatterers (PS), can be used as a "natural GPS network" to monitor terrain motion, analysing the phase history of each one. In this paper, results obtained using 34 ERS SAR images gathered over the Italian city of Ancona are presented.