Thiers (; Auvergnat: Tièrn) is a commune in the Puy-de-Dôme department of Auvergne in central France. With Ambert, Issoire and Riom, it is one of the department's four sub-prefectures. The district of Thiers consists of forty-three municipalities in six cantons. Its inhabitants are known as Thiernois or Bitords. Thiers is a major historical centre of knife manufacturing, with about one hundred companies and a cutlery museum; seventy percent of French pocketknives, kitchen and table knives are manufactured in Thiers. The knowledge and craft of the Thiernois cutlers are over seven centuries old, and many of the old watermills that were used to manufacture Thiernois knives can still be seen in the Vallée des Rouets. The city extends over on a rocky spur overhanging the nearby mountains and the villages. It is divided into two sections: the lower city (home to many hypermarkets) and the upper, medieval city. Overview Neighborhoods Thiers is on the steep hills overlooking the Durolle Valley, and the gradient provides hydropower for grinding mills. The city is divided into a number of neighborhoods. The upper town includes the medieval center, Boulay, the Pontel and the Jaiffours. Much of the city's history took place in its hills. The lower city began to be developed during the 1950s. Thiers is known as a city of hypermarkets and supermarkets, and the lower city primarily consists of businesses and services. Le Moutier, a prosperous neighborhood, is between the lower city and the city center. The doors of the church of Saint-Symphorien depict the mouth of hell and the plants of the nearby valleys. Many knife manufacturers are in the neighborhood. Hazards Thiers is vulnerable to natural disasters. The north of the city experienced two landslides in 1984: one along the A89 autoroute and the other in the Valley of the Mills. Earthquakes may also occur in Thiers, which is classified as a Zone 3 Seismic Area (moderate seismicity). The city, which on the Dore and Durolle Rivers and a number of streams, has a history of flooding. Exceptional weather occurs every few decades, and winds of were recorded in the city centre in 1999. In addition to natural hazards, the city is exposed to human-created risks. The Membrun Dam, on the Durolle, is a kilometre from the city's outskirts. In 1999, the mountain overlooking the city was the target of arsonists who set fire to the forest near the Margerides cliff.