Vajont Dam Landslide – 1963

The postwar recovery of the Italian economy was driven by the great industrial cities of the north and the Vajont Dam was one of a number of major hydroelectric schemes designed to service their increasing power needs. Sited in a deep valley in the Dolomites 100 km (62 mi) northeast of Venice, the double-curved arch dam was 265 m (870 ft) high and the artificial lake it created could hold 150 million cu m (33 billion gallons) of water. Although there was evidence of past landslides in the area and some concern over the stability of the slopes of Monte Toe which formed the south side of the reservoir basin, none of this impeded construction and the dam was duly finished in 1960.

A minor landslide occurred in November that year but this did not prevent the filling of the basin, which proceeded on a controlled schedule over the next three years. The reservoir was full nearly to capacity when on October 9 1963 a massive landslide dumped 260 million cu m (9 billon cu ft) of earth and rock into the water from the feared south bank. Not only did this push water up the opposite dope, engulfing a village hundreds of feet above, but it also created a giant wall of water which overwhelmed the dam. It is estimated that the landslide expelled nearly half the water in the reservoir. The sight of the seiche wave, which probably exceeded the crest of the dam by as much as 350 m (820 ft), must have been truly terrifying. The wave crashed down the valley, consuming everything in its path. By the time the flood waters finally settled, several more entire villages in the neighbouring Piave valley had been utterly destroyed.

When: October 9 1963

Where: Dolomites, Friuli, Italy

Death toll: At least 2,000 people died; the toll may have been as high as 2,600.

You should know: Remarkably, the dam itself survived the disaster intact and can still be seen today – though it is of course no longer in use.