Vajont Dam Disaster: 63 Years On, New Research Reexamines How the 1963 Landslide Killed Thousands

The Vajont Dam, on the border between the Veneto and Friuli-Venezia Giulia regions of northeastern Italy, was completed in 1959. According to Italy's national Civil Protection service, it was considered the country's most significant engineering project for electricity production at the time, and it was built without adequately accounting for the geological instability of the slopes around the reservoir it created below Mount Toc.

On the night of October 9, 1963, a mass of rock and earth estimated at about 270 million cubic metres broke away from Mount Toc's northern flank and slid into the reservoir in roughly a minute, according to Civil Protection. The displaced water, estimated at around 50 million cubic metres, surged over the top of the dam and down into the Piave valley.

The death toll

The wave destroyed the town of Longarone and damaged the villages of Erto and Casso, which sat closer to the reservoir itself. Civil Protection and Italian outlet CittaNuova both put the confirmed death toll at 1,917, with about 400 victims never recovered. Some English-language sources covering the anniversary have cited broader estimates ranging up to roughly 2,000 or more deaths, reflecting uncertainty over victims who were never formally identified.

What new research says about the collapse

The 63rd anniversary this year coincided with fresh scientific work on why the slope failed the way it did. According to CittaNuova, Italy's National Institute of Oceanography and Experimental Geophysics (OGS) in Trieste, working with the University of Parma, presented new findings on October 7, 2026, arguing that the landslide was not a single event but consisted of two rock blocks of different composition that moved at different speeds.

In that account, the second, faster-moving block effectively pushed against water that had already been raised by the first block's entry into the reservoir, amplifying the wave that eventually crossed the dam, according to CittaNuova's reporting on the OGS-University of Parma study.

A disputed power plant near the dam

The anniversary also reignited a local dispute over a proposed underground hydroelectric plant near the dam site. According to Italian outlet IlNordest, a company called Welly Red has proposed a roughly €12 million facility that would use a 123-metre water drop below the dam to generate an estimated 13.3 million kilowatt-hours a year, with construction designed to remain hidden inside the mountain.

IlNordest reports that the project has divided communities along the valley: Erto and Casso, upstream of the dam, have generally supported it as a source of local economic development, while Longarone, downstream, and the wider province of Belluno have opposed it, citing concerns about the site's role as a memorial. The outlet reports that a June 2026 regional decision exempted the project from a full environmental impact assessment, after which groups including "Vajont, il futuro della memoria" filed appeals with Italy's regional administrative court (TAR) in September and October 2026 challenging that decision.

A memorial disturbed

CittaNuova also reported an act of vandalism tied to the disaster's memory: in mid-September 2026, unidentified individuals removed a small statue of the Madonna, along with commemorative plaques and a summit registry, from the top of Croda Granda in the municipality of Gosaldo, in Belluno province. The statue had originally been recovered from the Piave riverbed after the 1963 disaster by volunteers from Fossalta di Piave and placed on the summit as a memorial; CittaNuova reports it was later found in a ravine and required a helicopter operation to retrieve.