The 1963 Vajont Landslide (Northeast Alps, Italy) Post-Conference Field Trip

The post-conference field trip focuses on the Vajont reservoir landslide, one of the best known examples of disasters induced by human activity; it offers the possibility to appreciate the complex- ity both of the surrounding area and of the particular geological, structural and geotechnical features of the landslide. The Vajont reservoir is located in the SE part of the Dolomite Region of the Italian Alps, about 100 km north of Venice. The doubly curved arch dam stands 265.5 metres above the valley floor and was the world’s highest thin arch dam when it was built. On October 9th, 1963, during the third fill- ing of the reservoir, a mass of approximately 270 million m3 detached from the left side of the valley and slid into the water at velocities up to 30 m/sec. A wave subsequently overtopped the dam by 250 m and swept into the Piave Valley below, resulting in approximately 2000 deaths. The sliding lasted less than one minute and produced seismic shocks, which were recorded throughout Europe. Remarkably the dam remained intact. The landslide moved mainly along a chair-shaped failure surface, which corre- sponded to a pre-existing slip surface as recognized before 1963 by E. Semenza. The 1963 slip surface was confined within 0.5–18 cm thick clay-rich lay- ers, which were almost continuous over large areas of the failure surface. The landslide was character- ized by a long-term phase of accelerating creep last- ing 2–3 years followed by the catastrophic failure.