This was the site of one of the most serious tragedies of the Italian twentieth century. Here it happened that a large landslide poured into the lake formed after the construction of the dam, causing a flood that wiped out many surrounding towns. On the night of October 9, 1963, about 270 million cubic meters of rock poured into the artificial basin below, creating a gigantic wave that hit the municipalities of Erto and Casso, destroying the villages that were on the shores of the lake. The villages of Longarone, Pirago, Faè, Villanova and Rivalta were completely destroyed and other villages in the Piave Valley suffered serious damage. In the end, 1917 people were killed. The landslide was caused by many factors: bad weather conditions, negligence in the attention to the hydrogeological structure of the slope of Monte Toc and the raising of the water level above the safe threshold, wanted by the managing body of the dam. Today the dam, which has remained intact, is open to the public for guided tours.