Epic Vajont Dam Disaster, Italy, 1963: Manmade or Natural?

On October 9, 1963, at 10:39 p.m., 1,000 feet of Italian Alp (specifically, Mount Toc), consisting of about 350 million cubic yards (268 million cubic meters) of heavy compact rock, slid northward into a vast reservoir containing 115 million cubic meters of water. The reservoir sat behind the spectacularly tall Vajont (pronounced in English: Vay-yont) dam, which cemented closed the west end of the Vajont Creek Valley. The mass of fallen rock completely blocked the narrow gorge to a depth of about 1,200 feet just behind the dam.

This amazing landslide took between 20 and 30 seconds to displace more than 50% of the reservoir’s water by first creating a giant wave of about 40,500 acre-feet (50 million cubic meters). The wave rose up as a mushroom to 820 feet (250 meters) in height, and then, in a 50 million-cubic meter tsunami rush, powered 25 million cubic meters of smelly water both upstream (eastward) to smash two small villages named Casso and Erto, and downstream (westward) over the top of the dam to crush five towns (Longarone, Pirago, Villanova, Rivalta, and Fae) in the valley of the Piave River. The entire upstream and downstream inundation occurred in less than seven minutes. One cubic meter of water weighs 2,200 pounds. The Vajont dam itself was unharmed.

About 2,000 (some sources say 2,600) people perished in this unusual disaster, and about 1,300 of the fatalities occurred in the town of Longarone (province of Belluno), resulting in a fatality rate there of 94%. Survivors on October 10, 1963, stood on bridges in the valley of the Piave River with poles desperately working to hook the bodies of humans and animals floating by to prevent their watery transport 100 miles to the Adriatic Sea near the city of Venice. Economic losses have never been definitively assessed as a result of litigation by plaintiffs, particularly families of the deceased in Longarone. One of the premises of the plaintiffs is that the disaster was manmade, not natural as the proprietors of the dam suggested.

This epic Italian national disaster is only now receiving full treatment in popular English, albeit in a round-about way. An Italian journalist named Tina Merlin, who for years wrote about the scourge of the dam construction from the perspective of the peasants of Erto and Casso, eventually published “On Living Flesh: How to Construct a Catastrophe” (“Sulla pelle viva: Come si costruisce una catastrofe”). Unfortunately, this book has yet to be translated from Italian into English, to the best of this writer’s knowledge.

However, an Italian story teller named Marco Paolini DID read Merlin’s book (in Italian) and, beginning in 1993, performed the 30-year old story as a professional master storyteller in Italy! After hundreds of performances he and a colleague committed to a transcription of the performance (in Italian), which another friend, Thomas Simpson of Northwestern University (Chicago), then edited and translated into English in 2000. Simpson writes in the Foreword to “The Story of Vajont” that he first became aware of the disaster in 1997 when he opened a copy of the Italian daily La Repubblica as he was riding an el train in Chicago and saw his old friend’s face glaring out at him from the Spettacolo section of the newspaper. (1) So there is a local connection to the Italian national epic disaster. (2)

In addition to “The Story of Vajont”, there are a number of good websites devoted to the Vajont disaster (3-5), and an Italian film by Renzo Martinelli titled “Vajont” (2001). (6) The Vajont Dam remains standing tall today, the valley behind it filled with landslide material, and is a popular tourist attraction.

Beginning Dam Construction

In 1929 two men named Dr. Carlo Semenza (an engineer) and Dr. Biorgio Dal Piaz (a geologist) visited the Vajont Valley to perform an initial feasibility study for a reservoir and dam to produce hydroelectric power. In 1956, when the villages of Erto and Casso in the valley boasted 850 and 450 residents, respectively, the Societa Adriatica di Elettricita (the Adriatic Electricity Society) or SADE visited the valley. The SADE had already built seven hydroelectric plants along the Piave River (the Vajont Valley runs into the Piave River Valley at right angles) and its tributaries in the previous 20 years. It needed a reliable source of water during the winter months to provide continuous electricity when the Piave River and its tributaries froze. Voila, the reservoir concept for the Vajont Valley emerged! The water in the Vajont Reservoir came from the Vajont Creek as well as drainoffs from other hydroelectric plants further up the mountains. This drainoff was delivered to the reservoir via about 20 miles of pipes.

SADE, which was originally privately owned by Count Volpi, pitched the “Grand Voyant” project to Mussolini’s Ministry of Public Works in 1940. But it was declined for three years because, according to Paolini in one of his signature dry passages, Italy was busy making war on France, then England, then Russia, and then America. (p. 19) The dam was finally approved on October 16, 1943 when Section Four of the Central Council of the Public Works Ministry called a meeting and 13 of the 34 members showed up. SADE officials waved the state approval document in front of the peasants of Erto and Casso and acquired their land.

SADE opened a construction site in the Vajont Valley and began work. In 1957 it sought a variance permit to increase the height of the dam from 200 meters (600 feet) to 261.60 meters. For the 200 meter dam, SADE had planned “a reservoir for 58 million cubic meters of water. But with a 261.60 meter wall they planned to contain 150 million cubic meters of water.” (p. 26) The Vajont dam is called a double-arch dam and remains today the largest of this kind in the entire world. Dr. Carlo Semenza designed it and by 1957 had become director of SADE’s hydraulic services division. He designed all of SADE’s hydroelectric plants on the Piave River and relished putting up this final dam across the outlet to the Vajont Valley as is final project before he retired. He was the chief engineer of the Vajont project.

The Ministry granted the variance request on June 15, 1957, but also requested the geological studies for the terrain at the dam AND the flanks of the valley. Meanwhile, SADE began building a ring road around the newly acquired property, but was asked to close down construction by a Belluno engineer named Desidera who was responsible for construction throughout the region. In less than 24 hours, “in response to the express wishes of the national Public Works Ministry”, the engineer was transferred elsewhere, notes Paolini.

Lake Potesei Hydroelectric Disaster 1958

A national-level government inspection committee formed in 1958 although it was ineffective in ensuring adherence to minimum safety standards during the dam’s construction by its private owners. The SADE entity was too strong. In March 1959 another hydroelectric reservoir called Lake Pontesei, 1 mile from Longarone, developed problems that were harbingers of Vajont’s fate. People began to notice yellow splotches bubbling to the surface of the Pontesei Reservoir, always in about the same place, meaning that the flanks of the mountain were absorbing water and a landslide was imminent. The solution, SADE engineers reasoned, was to drain the reservoir so that when the landslide moved down into the lake, less damage would occur (no huge wave splash). Paolini points out correctly that “if the flanks of the valley are filled with water like a sponge, …the water is holding them up. If you take away the water…now it’s a race to get the water out before the landslide happens.” (pp. 31-32) The landslide at Lake Potesei happened on March 22, 1959, killing security guard, Arcangelo Tiziani.

Peasants of Vajont Valley Fight Back

On May 3, 1959, according to Paolini, 126 heads of households in the Vajont Valley met to form the “Committee for the Rebirth of the Ertana Valley.” They learned that a new count named Vittorio Cini (of the powerful Venice Cini family) had bought SADE. Two newspapers were available in the area: The Gazzettino and the Communist paper L’Unita. Only Tina Merlin’s articles in the Communist newspaper reported on the dam and for her articles she was indicted for inciting problems, but was later released. The Gazzettino, owned by powerful interests, reported little about the dam, according to Paolini.

First Landside Fissures Develop and a Geological Terrain Study is Performed

During the building of the ring road around the reservoir in 1959, fissures developed on the southern side of the valley on the flank of Mount Toc. Roadbuilders were instructed to fill in the crevices and keep working but the cracks quickly reappeared. When Chief Engineer Semenza finally asked for the geological report of the valley’s terrain, he discovered that only a geological report of the dam site (not the valley terrain) had been performed. He then requested a survey by an Austrian named Leopold Muller of the Salzburg Geological Institute. Through his careful coring studies, Muller determined that the Mount Toc side of the valley was an ancient landslide 1.2 miles long and 1,800 feet high, which was in the process of creeping down Mount Toc. This was not good news for SADE and the Vajont project.

Semenza obtained a second opinion from his son, Edoardo, a degreed geotechnician, and another geologist, Franco Giudici, who verified the Austrian’s work and estimated the size of the incipient landslide at 200 million cubic meters of rock. Indeed, Edoardo determined that the ancient landslide was stable now, but eventually would make its way down the valley, with or without the reservoir.

Malpasset Dam Disaster, France 1959

On December 2, 1959, the Malpasset Dam in Frejus, France, only four years old, collapsed, killing 400 people. This was not good news for SADE.

Impoundments Begin

On January 2, 1960, SADE completed the concrete Vajont Dam and proceeded to the testing phase, which involved impoundment of various amounts of water. The first impoundment of water reached about half way up the inside of the dam. Paolini says that “[t]esting a dam is like testing a bridge. How do you test the weight capacity of a bridge? Simple: You load the bridge with trucks filled with cement blocks, then you drive them

away. If the bridge is still standing, it’s passed the test. Same thing for a reservoir: you put water in it, then drain the water out. If the dam is still there…that is, if it hasn’t shifted too much, because all dams move a little bit.” (p. 54)

First Landslide 1960

Meanwhile, Italy decided to nationalize its hydroelectric industry, which meant that the state could soon buy SADE’s new hydroelectric plant at the end of the Vajont Valley before SADE could make a profit. This added pressure to SADE, whose officials decided unilaterally to raise the water level to 660 meters (rather than the allowed 600 meters) above sea level. Unfortunately, they learned that the higher the water level reached, the more the foot of the creep zone creeped, sending yellow-brown bubbles to the surface of the reservoir, just like at Pontesei (see above)! This meant that a landslide was imminent, and in fact a 50 million cubic meter piece of rock did slide down into the reservoir on November 4, 1960, causing a large wave, but no one was hurt. SADE put up barbed wire around the whole landslide area for “safety” reasons. Paolini asks dryly: “Ah, thanks. Now safety’s a priority?” (p. 58) Tina Merlin’s husband walked high up the mountain and found a meter-wide fissure had also opened up along more than 7,000 feet of the mountain.

This news reached the Governor Da Borso of Belluno Province who started asking questions but received few answers. Civil engineers washed their hands of the affair. The most knowledgeable person available to Belluno was an engineer named Penta who was optimistic about the dam’s future. SADE installed two seismographs on top of the dam to assess movement and University of Padua geologists were commissioned to make and test a model of the dam. Unfortunately, a gravel load, rather than a cement load, was used to test the model, meaning that the findings of the test were not valid for Mount Toc. Meanwhile, SADE built a tunnel under the reservoir so that if the rock did move down and split the reservoir in two, it still could function as one for the purpose of producing hydroelectric power.

Second Impoundment

The government’s inspection committee authorized a second impoundment of water to an even higher level on December 23, 1961, two months after Carlo Semenza’s death on October 31, 1961. As the water level rose, the seismographs atop the dam became very active, setting off two out of every three days. In October, 1962, all the water was drained out of the reservoir and the mountain settled down again.

Nationalization Arrives

SADE passed the Vajont project to ENEL—the National Electric Energy Agency, on March 14, 1963. All the employees remained the same, more or less. However, SADE had sold a non-functioning hydroelectric plant because a successful and required third impoundment had not yet occurred. So SADE received for six days temporary custody of the Vajont Dam to bring the water to 715 meters above sea level, even though SADE was explicitly told early on in the design process never to exceed 700 meters above sea level or the dam might fail.

Third Impoundment

Starting on April 12, 1963, SADE received permission from the Public Works Ministry to raise the level of water to any height it wanted! The landslide on Mount Toc continued to destabilize. On July 27, 1963, ENEL took over complete ownership from SADE, inheriting a severely compromised situation. By the end of August 1963, the water reached 710 meters above sea level. By September 2, 1963, Mount Toc rumbled a grade 7 on the Mercalli scale—an earthquake, which toppled houses in Erto. Another tremor occurred on September 15, 1963. The chief engineer, a man named Biadene who took over from Semenza, told the citizens of Erto, who had written him a letter about the “earthquake”: “I shall not respond to the rather wild assertions advance by the Town of Erto. The situation is under the control of our local office.” (p. 82) It was not under control, of course, and on September 15, it became apparent that the entire slide zone was coming down in a single piece.

Landslide!

On September 17, 1963 the engineers turned off the incoming water for seven days. Even though the water level remained the same, Mount Toc continued to slide. The water level inside Mount Toc was the same level as the water in the reservoir. The mountain had become inert, without water resistance, just like at Pontesei (see above). Removal of water would be catastrophic and leaving it there would be catastrophic. None of this information was provided to the residents of the towns in the Piave Valley. Instead, Biadene left for Venice and wrote a letter to Penta in Rome that said: “May God grant us good fortune.” (p. 87)

The police were instructed to notify all people in Erto to remain alert. When the peasants asked, alert to what?, they were told nothing was wrong, but to sleep with one eye open.  Then roadblocks on the state highway were placed, according to Paolini, “apparently so as not to disturb the landslide”. At 10:39 p.m., “[t]he last thread of the spider web holding the massive rock to the rest of the mountain [broke].” Not everyone in Erto was killed by the tsunami wave that moved upstream (residents of Casso were spared). Downstream in Longarone, however, people, who had received no warning or instructions to evacuate, were taken by surprise. A roaring wind that preceded the foul-smelling water-wall killed almost everyone. The wind supposedly had a force or pressure two times the bombs dropped on Hiroshima. (p. 94) People’s clothes and skin were blown off and their internal organs blasted to death. What the wind didn’t destroy, the water did. It sloshed against one side of the Piave Valley and then the other and back and forth until it was able to make its way downriver, like a mouse in a snake’s gullet. The water-wall scoured and flattened everything (see photo).

Today, Longarone has been rebuilt and the wall quickly erected around Erto and Casso has been removed. Tourists can visit this historic site.

A Manmade Disaster?

The rationale behind claiming that the Vajont disaster was a manmade disaster was that the filling of the lake behind the dam hastened the destabilization of the ancient landslide on Mount Toc. The profit motive and capitalism have been blamed for cutting corners in the building of the dam, particularly in the acceleration of its construction and impoundment to outpace imminent nationalization of hydroelectric plants in Italy. The apparent lack of warning to people living in the dam’s failure flood footprint was unconscionable, even for 1963. In this sense, the disaster was manmade.

Sources:

1. Marco Paolini and Gabriele Vacis: “The Story of Vajont”, edited and translated by Thomas Simpson, published by Bordighera Press, 2000.

2. “Marco Paolini at Northwestern” at: http://www.frenchanditalian.northwestern.edu/related_links/more_italian_links/paolini.html; accessed June 17, 2006.

3. “The Vajont Landslide” by David Petley at: http://www.land-man.net/vajont/vajont.html; accessed June 17, 2006.

4. “Vajont: A Tragedy Unfolds” at: http://www.italiaplease.com/eng/megazine/giroditalia/2001/10/vajont/index.html; accessed June 17, 2006.

5. Vajont: Almost a Greek Tragedy” at: http://www.geocities.com/Athens/Acropolis/2907/vajont.html; accessed June 17, 2006.

6. “Vajont - La diga del disonore” (2001), directed by Renzo Martinelli; see: http://www.imdb.com/title/tt0214265/; accessed June 17, 2006.

7. See “La Catastrophe de Malpasset en 1959” at:

http://www.ecolo.org/documents/documents_in_french/malpasset/malpasset.htm; accessed June 17, 2006, and “Cracking Dams” at: http://simscience.org/cracks/intermediate/malpasset.html; accessed June 17, 2006.