Erto and Casso were the two villages in the Vajont valley, above the artificial lake, before the Vajont Dam disaster on October 9, 1963. The landslide and megatsunami killed almost 2000 people in total, destroying 5 villages in the Piave valley but leaving Erto and Casso only slightly damaged. The two villages were cautionally evacuated within 3 days of the disaster and the valley stayed empty for 3 years thereafter. During those years, some of the survivors settled down in the Maniago municipality, creating what would become the new Vajont municipality from 1971. Three years after evacuation, some other survivors, in spite of being forbidden to return to the valley, went back to their former houses and reformed the villages of Erto and Casso, which still make the municipality today.