1963 – 2023: 60 years from the Vajont dam disaster

It is October and, like every year in this period, it is the anniversary of the Vajont disaster: a tragic event that, despite its extent and importance, is not widely known. This year, in particular, marks the 60th anniversary of the disaster and the President of the Italian Republic Sergio Mattarella will attend the celebrations.

The Vajont disaster happened as a result of the construction of a dam inside the Vajont valley, in Northern Italy. The dam, known as Vajont dam and depicted in Figure 1, was built to hold up to 150 millions m3 of water. According to the most accredited hypothesis, the presence of the lake caused the mobilisation of a large and ancient landslide mass present on the left bank of the lake.

Figure 1 Vajont dam as seen from Longarone (Italy).

On 9th October 1963, at 10:39pm, a 270 million m3 landslide entered the lake at a velocity of 100 km/h.The large amount of material entering the lake so quickly caused the displacement of 50 out of around 115 million m3 of water present in the lake at the time. The resulting wave reached an height of 200 metres and divided into three parts: the first rose up the orographic right bank of the lake, the second travelled backwards across the lake and the third, of approximately 25 million m3, proceeded in the direction of the dam, jumped over it and flowed into the valley below. Each of the three parts of the wave razed everything in their path and caused the death of 1910 people.

Figure 2 Slip surface of Vajont landslide as seen from Casso (Italy).

The causes and those responsible for what happened have been the subject of a long trial and several scientific studies which are still trying to explain the mechanism of such an unprecedented event. The dynamics that led to the disaster and the subsequent implications have always aroused great interest on my part, since I learned about it at the age of seven. The interest in the matter has increased significantly over the last few years following the reading of a large number of books on the topic and the interaction with survivors and academics making research on the phenomenon. For the 60th anniversary, I decided to return to the places where the disaster took place to give my modest contribution on the topic: watch this space in the coming days to find out what it is.