Long term monitoring of unstable slopes by ground based synthetic aperture radar: A case stdy in Italy

A Ground Based interferometric SAR (GB SAR) was employed to monitor an active alpine landslide located in Citrin Valley (North Italy) for a time period of two years. Instead of measuring terrain movements continuously within a single measurement campaign, this work reports on data gathered on five different campaigns carried out sequentially from September 2003 to September 2005. The loss of coherence (decorrelation) is the main problem in these applications and some precautions were designed to control it. A solid platform, where the radar instrumentation was carefully reinstalled at each campaign, was built specifically in order to avoid geometric decorrelation between different campaigns. Suitable processing techniques similar to those used in satellite interferometry were adapted to the ground based configuration and used to compensate for the loss of coherence related to atmospheric and electromagnetic variations. The results obtained by means of these techniques within the two years long monitoring campaign are presented and discussed in this work.