October 9, 1963 Tsunami: Vajont Dam, Vajont River, Italy

Reference #10991:

1963, October 9. The landslide and flood at Vaiont Reservoir in northeast Italy is a famous engineering disaster caused by the failure to manage the effects of reservoir filling upon the stability of Monte Toc, just to the south. The disaster was unusual in that dam collapse did not trigger the ensuing flood. Rather, a catastrophic landslip from the slope of Monte Toc pushed ~1/5 of the water in the newly created reservoir overtop and around the dam. The 2.6x108 m3 slide mass flung down 30 million cubic meters of water to flood the Piave Valley below.

Reference #10992:

1963, October 9. The Vajont Landslide occurred at 10.39 pm in Italy, in the Dolomites of Friuli, on the borders of the Veneto Region and about 100 km north of Venice. A mass of approximately 270-300 million m3 of rock and debris collapsed into the reservoir generating a wave that over-topped the 261.6 m high double curved arch dam built across a V-shaped gorge. The flood wave dropped into the Piave Valley destroying the town of Longarone and other villages nearby. More than 2,000 people (the real number is not known) were killed.

Reference #10993:

1963, October 9. At 22:39 a huge landslide of about 270 million m3 slid from Mount Toc into the Vajont artificial reservoir, in north-eastern Italy. The amount of water in the basin at that moment was about 115 million m3. The resulting displacement of water caused the generation of an impulse wave that spread throughout the basin. Its impressive wave run-up on the north slope of the lake, in front of Mount Toc, reached and damaged buildings located in Casso about 235 m over the original height of the lake surface. The resulting wave rundown crashed into the front of the landslide and partially crossed over the slide bulk, reaching the depressions behind the slide. On the east side of the basin, a portion of the water which was pushed forward by the landslide formed a wave with smaller amplitude that travelled to the east, reaching the eastern most end of the reservoir in the mountains.

During the whole event several impulse waves crested the dam or moved onto the surrounding slopes which became a way for the water to move out into the narrow canyon that connects the dam to the Piave Valley. The mass of water that poured into the canyon, compressing the air, generated a wave of pressure that acted as a wind. This "wind", propagating at a speed greater than the waterfront, preceded the waterfront and produced the first damage in Longarone, before the water reached the town. The villages located along the Piave riverbed were completely devastated and turned into a flat plain of mud, with about 1700 casualties. The wave travelled upstream for about 5 km and in the downstream cross-sections of Ponte nelle Alpi and Belluno (located respectively at about 11 and 19 km from Longarone) the estimated maximum flow was 20% - 50% higher than the one observed during the famous 1966 flood wave.

The water depth of the wave in some points exceeded 50 m.

Reference #10995:

1963, October 9. In Monte Toc 260 million cubic meters of rock and stone in the lake provoked a wave of 50 million cubic meters of water that was sufficient enough to wipe off the face of the earth, in four minutes, 5 villages: Longarone, Pirago, Rivalta, Villanova, Fae; 2000 victims.