Urban subsidence in the city of Prato (Italy) monitored by satellite radar interferometry

Differential Synthetic Aperture Radar (SAR) interferometry has been widely used to monitor centimetric surface deformations in geophysical applications. In this letter, this technique is applied to study the displacement field in an urban area. A set of six European Remote Sensing satellite (ERS)-1/2 SAR images has been used to detect, map and quantify the subsidence occurring in the city of Prato near Florence (Italy). Four areas which have been affected by strong subsidence during the period 1993-2000 have been spotted within the city. The analysis of three interferograms processed from images taken two years apart shows that the deformation rate appears to be relatively constant, with a maximum value of about 8.3 cm y(-1).