At 22:38 GMT on 9th October 1963 catastrophic failure of the landslide occurred on the slope
The entire mass slid approximately 500 m northwards at up to 30 m/sec. The mass completely blocked the gorge to a depth of up to 400m , and it travelled up to 140 m up the opposite bank. Movement of the landslide mass ceased after a maximum of 45 sec. At the time the reservoir contained 115 million cubic metres of water. A wave of water was pushed up the opposite bank and destroyed the village of Casso, 260 m above lake level before over-topping the dam by up to 245 m. The water, estimated to have had a volume of about 30 million cubic metres, then fell more than 500 m onto the villages of Longarone, Pirago, Villanova, Rivalta and Fae, totally decimating them.
A total 2500 lives were lost.
The image below shows the location of these villages after the flood. The valley floor, on which the villages were located, has been wiped clean by the water. The flood wave came down the Vajont valley,
