Vajont Dam

The dam was built by Società Adriatica di Elettricità (SADE), the electricity supply and distribution monopoly in northeastern Italy. The owner, Giuseppe Volpi di Misurata, had been Mussolini's minister of finances for several years. The "tallest dam in the world", across the Vajont Gorge, was conceived in the 1920s to harness the Piave, Mae, and Boite Rivers, to meet the growing demand for power generation and industrialization. The project was not authorized until 15 October 1943, after the confusion following Mussolini's fall during World War II was resolved.[7]

The dam wall had a volume of 360,000 m³ (13×10^⁶ cu ft) and held up to 168.7×10^⁶ m³ (5.96×10^⁹ cu ft) of water. The dam and basin were intended to be at the centre of a complex water-management system in which water would have been channeled from nearby valleys and artificial basins at higher levels. Tens of kilometres of concrete pipes and pipe bridges across valleys were planned.

In the 1950s, SADE's monopoly was confirmed by post-fascist governments, and it bought the land despite opposition by the communities of Erto and Casso in the valley, which was overcome with government and police support. SADE stated that the geology of the gorge had been studied, including analysis of ancient landslides, and that the mountain was believed to be sufficiently stable.

Construction work started in 1957. By 1959, shifts and fractures were noticed while building a new road on the side of Monte Toc. This led to new studies in which three experts separately told SADE that the entire side of Monte Toc was unstable and would be likely to collapse into the basin if the filling were completed.[8] SADE took no notice and construction was completed in October 1959; in February 1960, SADE was authorised to start filling the basin. In 1962, the dam was nationalized and came under the control of ENEL as part of the Italian Ministry for Public Works.

On 22 March 1959, during construction of the Vajont Dam, a landslide at the nearby Pontesei Dam created a 20-metre-high (66 ft) wave that killed one person.[9] Throughout the summer of 1960, minor landslides and earth movements were noticed. Instead of heeding these warning signs, the Italian government chose to sue the handful of journalists reporting the problems for "undermining the social order".[10]

On 4 November 1960, with the water level in the reservoir at about 190 m (620 ft) of the planned 262 m (860 ft), a landslide of about 800,000 m³ (30×10^⁶ cu ft) collapsed into the lake. SADE stopped the filling, lowered the water level by about 50 m (160 ft), and started to build an artificial gallery in the basin in front of Monte Toc to keep the basin usable even if additional landslides (which were expected) divided it into two parts.[11]

In October 1961, after the completion of the gallery, SADE resumed filling the narrow reservoir under controlled monitoring. In April and May 1962, with the basin water level at 215 m (705 ft), the people of Erto and Casso reported five "grade five" Mercalli intensity scale earthquakes. SADE downplayed the importance of these quakes,[12] and was then authorized to fill the reservoir to the maximum level.

In July 1962, SADE's own engineers reported the results of model-based experiments on the effects of further landslides from Monte Toc into the lake. The tests indicated that a wave generated by a landslide could top the crest of the dam if the water level were 20 m (66 ft) or less from the dam crest. SADE therefore decided that a level 25 m (82 ft) below the crest would prevent any displacement wave from over-topping the dam. A decision was made to fill the basin beyond that, because the engineers thought they could control the rate of the landslide by controlling the level of water in the reservoir.

In March 1963, the dam was transferred to the newly constituted government service for electricity, ENEL. During the following summer, with the basin almost completely filled, slides, shakes, and movements of the ground were continuously reported by the alarmed population. On 15 September 1963, the entire side of the mountain slid by 22 cm (8.7 in). On 26 September 1963, ENEL decided to slowly empty the basin to 240 m (790 ft). In early October 1963, the collapse of the mountain's south side looked unavoidable; in one day, it moved almost 1 m (3 ft).

The hydraulic model, during the first series of tests.

After the discovery of the landslide on the northern slopes of Monte Toc, it was decided to deepen the studies on these effects:

• Dynamic actions on the dam
• Wave effects in the reservoir and possible dangers for nearby locations, with particular attention to the town of Erto
• Hypothesis of a partial breakage of the dam and consequent examination of the rout wave and its propagation along the last stretch of the Vajont and along the Piave, up to Soverzene and beyond

The study of point 1 was performed at the Experimental Institute for Models and Structures (ISMES) of Bergamo, while for the others, the SADE decided to build a physical-hydraulic model of the basin, in which to perform some experiments on the effects of a landslide fall in a reservoir.

The 1: 200 scale model of the basin, which can still be visited today, was set up at the SADE hydroelectric plant in Nove (Borgo Botteon di Vittorio Veneto), and became the Hydraulic Models Centre. The experiments were entrusted to professors Ghetti and Marzolo, university professors of the Institute of Hydraulics and Hydraulic Constructions of the University of Padua, and were carried out with funding of SADE, under the control of the study office of the company itself.

The study aimed to verify the hydraulic effects on the dam and on the banks of the landslide reservoir, so was directed in this sense rather than reproducing the natural phenomenon of the landslide. The experiments were carried out in two different series (August–September 1961 and January–April 1962), of which the first served substantially to refine the model.

Vajont Landslide

View of the village of Longarone, which was below the dam, showing the extent of the damage after the megatsunami had passed through
Native name	Italian: Disastro del Vajont
Date	October 9, 1963 (1963-10-09)
Time	22:39 (CET)
Coordinates	46°16′02″N 12°19′44″E
Type	Dam failure
Cause	Underestimated speed and mass of landslide of Monte Toc
Casualties
1,900-2,500 fatalities (estimated)
Deaths	1,917
Missing	1,300
Property damage	500,000,000,000 Lira (1963)
Charges	Manslaughter and causing the disaster
Trial	L'Aquila

On 9 October 1963, engineers saw trees falling and rocks rolling down into the lake where the predicted landslide would take place. Before this, the alarming rate of movement of the landslide had not slowed as a result of lowering the water, although the water had been lowered to what SADE believed was a safe level to contain the displacement wave should a catastrophic landslide occur. With a major landslide now imminent, engineers gathered on top of the dam that evening to witness the tsunami.

At 10:39 pm, a massive 2-kilometre-long (1.1 nmi; 1.2 mi) landslide, with around 260×10^⁶ m³ (9,200×10^⁶ cu ft) of forest, earth, and rock, fell from the northern flank of Monte Toc into the lake below at up to 110 km/h (31 m/s; 59 kn; 68 mph) (another source gives 25 m/s (90 km/h; 49 kn; 56 mph)[14]), generating a seismic shock. In 20 seconds it reached the water level; by 45 seconds the landslide (now at rest) had completely filled the Vajont reservoir. The impact displaced 115×10^⁶ m³ (4,100×10^⁶ cu ft) of water in about 25 seconds, 50×10^⁶ m³ (1,800×10^⁶ cu ft) of which overtopped the dam in a 1⁄4 km-high (250 m; 820 ft) wave.[1][15][4]

The impact with the water generated three waves. One went upwards, reached the houses of Casso, fell back onto the landslide, and went on to dig the basin of the pond of Massalezza. Another headed toward the shores of the lake, and through a washout action of the same, destroyed some localities in the municipality of Erto e Casso. The third (containing about 50×10^⁶ m³ (1,800×10^⁶ cu ft) of water) climbed over the edge of the dam, which remained intact except for the ring road that led to the left side of the Vajont, and fell into the narrow valley below.

The roughly 50×10^⁶ m³ (1,800×10^⁶ cu ft) of water that managed to climb over the work reached the stony shore of the Piave Valley and swept up substantial debris, which poured into the southern sector of Longarone and destroyed the town except for the town hall, the houses north of it, and other neighboring towns. The death toll was about 2,000 people (official data speak of 1,917 victims, but determining with certainty the number is impossible).[16]

The firefighters who departed from Belluno, after receiving reports about the raising of the level of the Piave, could not reach the location, since from a certain point onwards, the road coming from the valley had been completely ripped off. Longarone was reached by firefighters who departed Pieve di Cadore, who were the first to realize what had happened and were able to communicate it. At 5:30 am on 10 October 1963, the first soldiers of the Italian Army arrived to bring relief and recover the dead. The soldiers involved were mostly Alpini, some of whom belonged to the combat engineers, who dug by hand to seek the bodies of the missing. They also found safes of the banks of the country, no longer able to be opened with normal keys, as they were damaged.[17] The firefighters from 46 Provincial Commands also participated in the rescue, with 850 men, including divers, land and helicopter teams, and many vehicles and equipment. The Nucleo Sommozzatori of Genoa, with eight personnel, was used in the basin in front of the Busche Dam, for dredging to search for bodies and drums of toxic substances (61 cyanide drums), with subsequent patrol by immersion and final removal of sludge when the basin was dry. Of the nearly 2,000 fatalities, only 1,500 bodies have been summarily recovered and recomposed, half of which are impossible to recognize.[15]

The flooding in the Piave Valley from the wave destroyed the villages of Longarone, Pirago, Rivalta, Villanova, and Faè, killing approximately 2,000 people and turning the land below the dam into a flat plain of mud[18] with an impact crater 60 m (200 ft) deep and 80 m (260 ft) wide. Many small villages near the landslide along the lakefront suffered damage from a giant displacement wave. Villages in the territory of Erto e Casso and the village of Codissago, near Castellavazzo, were largely wrecked.[19]

Estimates of the dead range from 1,900 to 2,500 people, and around 350 families lost all members. Most of the survivors had lost relatives and friends along with their homes and belongings.[20] The dam was largely undamaged. The top 1 m (3.3 ft) or so of masonry was washed away, but the basic structure remained intact and exists today.

Overview of the Vajont Valley shortly after the disaster of 9 October 1963: Note the 260×10^⁶ m³ (9.2×10^⁹ cu ft) landslide, which broke off from Monte Toc and fell into the artificial basin.

Immediately after the disaster, the government (which owned the dam), politicians, and public authorities insisted on attributing the tragedy to an unexpected and unavoidable natural event. The debate in the newspapers was heavily influenced by politics. The paper l'Unità, the mouthpiece of the Partito Comunista Italiano (PCI), was the first to denounce the actions of the management and government, as it had previously carried a number of articles by Tina Merlin addressing the behaviour of the SADE management in the Vajont project and elsewhere. Indro Montanelli, then the most influential Italian journalist and a vocal anticommunist, attacked l'Unità and denied any human responsibility; l'Unità and the PCI were dubbed "jackals, speculating on pain and on the dead" in many articles by La Domenica del Corriere and a national campaign poster paid for by the Christian Democracy, the party of Prime Minister Giovanni Leone. They attributed the catastrophe only to natural causes and God's will.[21]

The campaign accused the PCI of sending agitprops into the refugee communities, as relief personnel; most of them were partisans from Emilia Romagna who fought on Mount Toc in the Second World War and often had friends in the stricken area.[22] The Christian Democracy accused the Communist Party of "political profiteering" from the tragedy. Leone promised to bring justice to the people killed in the disaster. A few months after he lost the premiership, he became the head of SADE's team of lawyers, who significantly reduced the amount of compensation for the survivors and ruled out payment for at least 600 victims.[23][24]

The bell tower that remained standing at Longarone. The rest of the church building was swept away, as were almost all of the other structures in the village.

The DC's newspaper, La Discussione,[25] called the disaster "a mysterious act of God's love", in an article that drew sharp criticism from l'Unità.[26] Apart from journalistic attacks and the attempted cover-up from news sources aligned with the government, flaws in the geological assessments have been proven, with disregard of warnings about the likelihood of a disaster by SADE, ENEL, and the government. The trial was moved to L'Aquila, in Abruzzo, by the judges who heard the preliminary trial, thus preventing public participation, and resulted in lenient sentencing for a handful of the SADE and ENEL engineers. One SADE engineer (Mario Pancini) committed suicide in 1968. The government never sued SADE for damage compensation.

Subsequent engineering analysis has focused on the cause of the landslide, and debate continues about the contribution of rainfall, dam level changes, and earthquakes as triggers of the landslide, as well as differing views about whether it was an old landslide that slipped further or a completely new one.[27] A number of problems existed with the choice of site for the dam and reservoir; the canyon was steep-sided, the river had undercut its banks, and the limestone and claystone rocks that made up the walls of the canyon were interbedded with the slippery, clay-like Lias and Dogger Jurassic-period horizons and the Cretaceous-period Malm horizon, all of which were inclined towards the axis of the canyon. In addition, the limestone layers contained many solution caverns that became only more saturated because of rains in September.[28] Prior to the landslide that caused the overtopping flood, the downhill creep of the regolith had been 1.01 cm (0.40 in) per week. In September, this creep reached 25.4 cm (10 in) per day until finally, the day before the landslide, the creep was measured at 1 m (3.3 ft).[28]

The area of the 1963 landslide on Monte Toc, taken in 2005

Most of the survivors were moved into a newly built village, Vajont, 50 km (31 mi) southeast on the Tagliamento River plain. Those who insisted on returning to their mountain life in Erto e Casso were strongly discouraged. Longarone and other villages in the Piave Valley were rebuilt with modern houses and farms. The government used the disaster to promote the industrialization of northeastern Italy. Survivors were entitled to "business start-up" loans, public subsidies, and 10 years of tax exemption, all of which they could "sell on" to major companies from the Venice region. These concessions were then converted into millions of lira for industrial plants elsewhere. Among the corporations were Zanussi (now owned by Electrolux), Ceramica Dolomite (now owned by American Standard), Confezioni SanRemo, and SAVIC (now owned by Italcementi).[29]

Compensation measures did not clearly differentiate between victims and people who lived nearby; thus, much of the compensation went to people who had suffered little damage, creating a negative public image. A pumping station was installed in the dam basin to keep the lake at a constant level, and the bypass gallery was lengthened beyond the dam to let the water flow down to the Piave Valley. The dam wall is still in place and maintained, but no plans exist to exploit it. The dry basin, filled with landslip, has been open to visitors since 2002.

In recent years, revival of interest has occurred both by researchers with specialist interest and sightseers. The dam, now owned by ENEL, was partially opened to the public in 2002 with guided tours and access to the walkway along the top and other locations. In September 2006, an annual noncompetitive track event, called "Paths of Remembrance", was inaugurated, which allows participants to access some locations inside the mountain. On 12 February 2008, in launching the International Year of Planet Earth, UNESCO cited the Vajont Dam tragedy as one of five "cautionary tales" caused by "the failure of engineers and geologists".[30]

For 2013, on the occasion of the 50th anniversary of the disaster, the region of Venice set aside one million euros for safety works and recovery of tunnels inside the mountain, which were part of the Colomber Road (the old national road 251). The memorial church in Longarone—constructed over the strong opposition of the surviving parish priest— was built by architect Giovanni Michelucci.

After the initial worldwide reporting,[31] the tragedy became regarded as part of the price of economic growth in the 1950s and 1960s. Interest was rejuvenated by a 1997 television program by Marco Paolini and Gabriele Vacis, Il racconto del Vajont. In 2001, a docudrama about the disaster was released. A joint production of Italian and French companies, it was titled Vajont—La diga del disonore ("Vajont—The Dam of Dishonour") in Italy, and La Folie des hommes (The Madness of Men) in France. It stars Michel Serrault and Daniel Auteuil. The tragedy was included in the 2008 documentary series Disasters of the Century.[32]

The TV show Seconds from Disaster featured the event in episode two, "Mountain Tsunami", of its fifth season in 2012.[3][33] In 2013, the 11th stage of the Giro d'Italia finished in Vajont to commemorate the 50th anniversary of the disaster.[34] In March 2018, the dam and the disaster were also covered in season two, episode one ("Armageddon Highway") of Science Channel's Mysteries of the Abandoned.[35]

• List of natural disasters by death toll
• List of dams and reservoirs
• Malpasset Dam
• Seiche
• St. Francis Dam

• Franco Mantovania and Claudio Vita-Finzi, 'Neotectonics of the Vajont dam site', Geomorphology, Vol. 54, Issues 1–2, 2003, pp 33–37.
• David Petley, Landslide information: The Vajont (Vaiont) Landslide Archived 13 August 2006 at the Wayback Machine, 2001. Retrieved January 2008.
• Suburban Emergency Management Project (SEMP), 'Epic Vajont Dam Disaster, Italy, 1963: Manmade or Natural?', Biot #373: 17 June 2006. Retrieved January 2008.

Video on YouTube of 3D simulation of the wave generated by the Vajont rockslide.

Wikimedia Commons has media related to Vajont Dam.

• Kiersch, G. A. The Vajont Reservoir Disaster. Mineral Information Service, July 1965, pp. 129–38. (in English)
• Vajont dam disaster: a fascist legacy (in English)
• Vajont forecast manslaughter (in English)
• Sito documentale antimafia Vajont (in Italian)
• Eyewitnesses, 1964's original movie (2.000 condanne) (in Italian)
• The last outrage: in fact, a mere commercial business. Again... (in Italian)
• ...Testuale: i festeggiamenti del cinquantesimo della tragedia (in Italian)
• Vajont, l'onda lunga, Lucia Vastano. Libro inchiesta, testo di corso IUAV Venezia (in Italian)
• Il disastro del Vajont Archived 15 April 2021 at the Wayback Machine (in Italian)
• Comitato Sopravissuti del Vajont (in Italian)
• Vajont: Almost a Greek Tragedy (in English)
• Vajont, La diga del disonore at IMDb
• Vajont dam photos and virtual field trip (University of Wisconsin). Retrieved 2 July 2009