The Vajont Dam landslide and seiche left 1,909 people dead and the villages of Longarone, Pirago, Rivalta, Villanova, and Fae destroyed.
The Vajont Dam landslide and seiche occurred on 9 October 1963, at about 22:35, when heavy rains triggered a landslide on Monte Toc, behind the dam. 260 million cubic meters of Monte Toc slid into the Vajont reservoir at speeds up to 110 km (68m) per hour; the resulting seiche sent 50 million cubic meters of water rushing over the top of the Vajont Dam.
Authorities had not been without warning of the dangers of building a reservoir at the base of Monte Toc. The Vajont Dam was completed in 1959; frequent landslides and earth movements alarmed journalists and local citizens throughout the years until the landslide and seiche devastated the Piave Valley below in October 1963. The Italian government failed to take seriously the concerns of the citizenry; SADE, who owned the Vajont Dam, ignored its own engineers when they predicted disaster in July of 1962.
The Italian government used the disaster to promote the industrialization of the Piave Valley. The Vajont Dam has been repaired and was opened to visitors in 2002.