A piece of Monte Toc slid into the reservoir in 1963, and the water it displaced went over the top of the dam and down into the valley, where it destroyed Longarone and the villages near it and killed around two thousand people.
The dam is still standing. Almost nothing happened to it; it holds its curve, 262 metres of concrete in a narrow gorge, and you can walk out along the crest. Above it the mountain carries the scar where the rock came away, pale and bare against the trees, and it has not closed over in all the years since. Longarone was rebuilt below, on the plan of the old streets, with a cemetery of identical stones for the dead who could be counted and for those who could not.
At Fortogna the stones went up numbered at first, because that was what could be known. Names were added later, slowly, as the identifications were made and the families asked — a long, patient correction that took decades.
The slope had been creeping measurably for years before that night, and the readings were on file. Some of the families in Longarone had been told the mountain was watched.