Geomorphological characterization, monitoring and modeling of the Monte Rotolon complex landslide (Recoaro Terme, Italy)

The Rotolon landslide, located in the upper Agno River valley (Vicenza, Italy), has threatened the valley for centuries. During November 2010, after 637 mm of rainfall in 12 days, a debris mass of about 225,000 m3 collapsed from the lowermost portion of the landslide and evolved into a debris flow that channeled in the Rotolon Creek riverbed, damaging the villages of Maltaure and Parlati in the Recoaro Terme municipality. On December 8th, 2010 the Department of Earth Sciences of the University of Firenze started a real-time monitoring using a GB-InSAR radar interferometer. The radar data are elaborated to obtain weekly, monthly and total cumulated 3D displacement maps and displacement time series of ten control points selected on the landslide mass. Accurate field surveys were carried out to analyze the landslide physiographic features and to validate the ground deformation retrieved from the radar data. The geomorphological features, supported by the radar data, led to an interpretation of the complex Rotolon landslide as a Deep Seated Gravitational Slope Deformation, whose detrital cover is often affected by detachments triggering debris flows. The November 2010 detachment area was modeled in order to: (i) calculate the main geotechnical properties of the collapsed material by means of a back analysis; (ii) define the residual risk; (iii) simulate new critical scenarios for the new topographic slope surface.