Malpasset Dam

The Malpasset Dam was an arch dam (convex surface facing upstream) on the Reyran River, north of Fréjus on the French Riviera. It collapsed on 2 December 1959, killing 423 people in the resulting flood. The breach was caused by a tectonic fault in the impermeable rock base, which had been inadequately surveyed. Nearby road-building works, using explosives, may also have contributed to the disaster.