Ground-based SAR interferometry as a supporting tool in natural and man-made distasters

In this work we present some applications of Ground-Based Synthetic Aperture Radar (GBSAR) interferometry to the monitoring of dams, bridges and landslides. A SAR system is a coherent active microwave device able to provide 2D refractivity images of a given area with high spatial resolution, independently of weather conditions and day-night cycle. SAR interferometry is the most notable application of SAR technology. This technique relies on the processing of a time series of coherent SAR images. It gives a powerful tool to produce maps of deformations occur-ring in infrastructures (dams, buildings, bridges) or terrain. In the last few years the research ac-tivity of several remote sensing groups has dealt with the development of GBSAR systems. GBSAR sensors represent a cost-effective solution for the continuous monitoring of small scale deformation phenomena if compared to space and air-borne systems. These systems basically con-sist of a CW radar mounted on a sliding support and synthesizing in time an aperture longer than the physical dimension of their real antennas. The main advantage of GBSAR displacement meas-urements, provided with a sub-millimetre accuracy, is that they provide the spatial pattern of the deformation phenomenon and not only measurements in a few selected points as in the case of tra-ditional geotechnical instruments. Some examples of application of GBSAR technology are de-scribed The GBSAR results are compared to measurements obtained by traditional instruments.