The area around the Alpe di Roscera above Preonzo (TI) had been moving for years and was observed using extensometers and laser distance measurements. In April 2012, increased speeds were detected - signs of an imminent rockfall?
In order to observe the rock movements more precisely and regardless of the weather, an interferometric radar was installed at a distance of around 2 km as the crow flies at the foot of the slope. The radar can be used to scan the rock face with high resolution and measure movements in the rock face with millimeter precision and from a safe distance. The station was operational on May 1st and transmitted the first measurement data live. After initial movements of 1 mm/h, these accelerated threefold after heavy rainfall on May 6th/7th. A week later, the final acceleration began, whereupon the affected area in the run-off area was evacuated and the road closed. Analyses estimated the time of the landslide to be between late evening on May 14th and during the day on May 15th. In the early hours of May 15, the time had finally come: approximately 220,000 m3 of rock fell over several hours. The remaining unstable areas continued to be monitored by radar after the event, but no further collapses occurred and the mountain quickly came to rest.