Long term landslide monitoring by ground-based synthetic aperture radar interferometer

A ground-based synthetic aperture radar (GB SAR) interferometer was employed to detect small terrain movements which occurred over long periods of time on a landslide hazard zone in the Citrin Valley in northern Italy. Three measurement campaigns were carried out from September 2003 to September 2004. The radar instrumentation was carefully re-installed at each campaign on the same observation point in order to avoid geometric decorrelation. Because of the global loss of coherence due to the long temporal separation between the observations, the retrieved displacements are limited to a number of very coherent points throughout the surveyed scenario. Radar data are locally compared with data provided by a global positioning system (GPS) network installed on the area interested by the landslide. Digital elevation model, photographic images, interferometric and GPS data are integrated within GIS environment providing a very effective geophysical knowledge tool.