Field monitoring of the Corvara landslide (Dolomites, Italy) and its relevance for hazard assessment

The Corvara landslide is an active slow moving rotational earth slide - earth flow, located uphill of the village of Corvara inBadia, one of the main tourist centres in the Alta Badia valley in the Dolomites (Province of Bolzano, Italy). Present-daymovements of the Corvara landslide cause National Road 244 and other infrastructures to be damaged on a yearly basis. Themovements also give rise to more serious risk scenarios for some buildings located in front the toe of the landslide. For thesereasons, the landslide has been under observation since 1997 with various field devices that enable slope movements to bemonitored for hazard assessment purposes. Differential GPS measurements on a network of 47 benchmarks has shown thathorizontal movements at the surface of the landslide have ranged from a few centimetres to more than 1 m between September2001 and September 2002. Over the same period, vertical movements ranged from a few centimetres to about 10 cm, with themaximum displacement rate being recorded in the track zone and in the uppermost part of the accumulation lobe of thelandslide. Borehole systems, such as inclinometers and TDR cables, have recorded similar rates of movement, with the depthsof the major active shear surfaces ranging from 48 m to about 10 m. From these data, it is estimated that the active component ofthe landslide has a volume of about 50 million m3. In this paper the monitoring data collected so far are presented and discussedin detail to prove that the hazard for the Corvara landslide, considered as the product of yearly probability of occurrence andmagnitude of the phenomenon, can be regarded has as medium or high if the velocity or alternatively the volume involved isconsidered. Finally, it is also concluded that the monitoring results obtained provide a sound basis on which to develop andvalidate numerical models, manage hazard and support the identification of viable passive and active mitigation measures.