Monte Toc falls into the Vajont
On 9 October 1963, about 270 million cubic metres of Monte Toc slid into the reservoir behind the Vajont dam, then one of the tallest arch dams in the world. The wave overtopped the dam, which itself survived almost intact, and swept down the Piave valley, destroying Longarone and nearby villages and killing roughly 1,900-2,000 people in minutes. The mountain's instability had been known for years: a smaller slide occurred in 1960, and a perimeter crack on the mountainside was being monitored.