State services have listed six main risks that could affect the municipality: forest fires; runoff and landslides; meteorological phenomena (strong winds, storms, squalls); earthquakes (seismicity of 2/5); transportation of hazardous materials; and radon, a radioactive gas that can be found near nuclear power plants. Some are more important than others.
With regard to violent meteorological episodes, it is necessary to go back to August 19, 1815 to see storms of incredible violence that take over the city, causing considerable losses: destroyed crops, meadows and lands drowned by water, houses and mills. landscape.
The most recent story takes us to November 10, 1982 when Ribbon City was caught in a storm. The same year, from November 16 to 28, heavy snowfalls decimated the forest. The snow was very intense and this phenomenon had been called “blue snow”. There was no more electricity, no factory was running, the villages were isolated… Some young volunteers brought supplies to the villagers for cross-country skiing. Only one baker was open, Isidore Bonnefoy, who baked his bread over a wood fire: the Saint-Justaires were rationalized.
The last earthquake that was felt in the city took place on February 19, 1822, but it was of low amplitude and had caused very little damage.
In 2008, severe thunderstorms triggered landslides below RD500. It still happens that such phenomena hit the city, but since phase 1 of the works in the Sambalou pedestrian park, the risk of flooding in the Pêcher district has decreased considerably.
A real nuclear risk
Regarding radon, the risk is medium / high. It is linked to a radioactive gas produced by the disintegration of uranium present in rocks. In a radius of less than 140 km, there are six nuclear power plants. The closest is Saint-Alban-du-Rhône (Isère), which is only 35 km as the crow flies. The others are Cruas in Ardèche (86 km), Bugey in Saint-Vulbas in Isère (90 km), Creys-Malville in Isère (102 km), Tricastin in Saint-Paul-Trois-Châteaux in Drôme ( 117 km) and Marcoule in the Gard (137 km). However, it should be noted that for Tricastin and Cruas, production should stop in 2035.