The Vajont Dam is located on the Vajont River in Italy. It was completed in the late 1950s and stands 262 metres tall, making it one of the world’s tallest dams at the time and still today.
About Vajont Dam
Even before the dam was erected, the Vajont River canyon was known to be geologically unstable; yet, Italy’s growing demand for energy pushed development forward.
Construction on the dam began in 1956 and was completed around 1960. It was carried out by Società Adriatica di Elettricità (SADE), a business that virtually controlled the Italian energy industry.
People began to notice several abnormalities in the mountains surrounding the dam as building began. People began discovering cracks and fractures in the ground while building a route onto the slope of the mountain to the dam .
Many people were afraid that filling the reservoir would jeopardise the integrity of the mountains surrounding it, and many experts warned of the dangers of filling the reservoir too quickly and the prospect of a single catastrophic landslide. Nonetheless, SADE mostly ignored the warnings, and the Italian government, according to some reports, sued journalists who reported the story for “undermining social order.”
Despite these fears, which were regarded as worst-case situations, SADE built the dam and began filling the reservoir in 1960.
When the lake reached 180 metres deep (rather than the projected 260 metres), a landslide of over 1,000,000 cubic metres collapsed into it. It was a red flag. The water level was soon reduced by technicians.
Engineers knew at this point that the water-logged left side of the mountain was intrinsically unstable. Controlling the entire slope, on the other hand, would be an impossible task. “It appeared hopeless to arrest the slide artificially,” one of the lead engineers claimed, “since all means that would have required to be deployed were beyond human boundaries.” As a result, dam experts decided to keep a close eye on the surrounding mountains and control the water level.
After roughly a year and a half of meticulous management, SADE personnel began rapidly boosting the dam’s water level. The water level was raised from 185m to 231m over a three-month period. By September 1962, the water had risen to around 235 m. At the time, specialists monitoring the mountain indicated that the land was moving at up to 3.5 cm/day, up from 0.3 cm/day just a year before.
Around this time (July 1962), SADE engineers conducted an analysis of the mountainsides surrounding the dam and determined that, in the case of a landslide, the wave would not topple the dam if the ground was moving at 20 MPH and the water was 20m below its maximum level. As a result, the water was kept 25 metres below its maximum level, at 235 metres.
October 9, 1963
Engineers began to see fallen trees and rocks in the region where the landslide was expected to occur.
They take a breather for a moment. Nothing major will occur if everything goes as planned. A tiny wave will form, collide with the dam, and everything will return to normal.
A gigantic landslide of 260,000,000 cubic metres of dirt, forest, and rock begins to hurtle downward at an astonishing 68 MPH, more than three times the original projected pace, at 10:39 PM.
A massive 250m wave emerged, crashing over the dam and into the valley below. The settlements of Pirago, Villanova, Rivalta, and Fae were completely destroyed in a matter of seconds. Thousands of people were killed.