Orne

Recorded Natural Hazards (Géorisques)

It has 381 municipalities and 275,201 inhabitants. Under the seismic zoning in force since 2011, its highest seismicity is low (zone 2 of 5). A natural disaster has been declared 1,360 times since 1982 (one declaration per municipality and decree), mostly for floods (878) and ground movements (395). The most recent was signed on 8 July 2025. 136 municipalities have a high radon potential (category 3), home to 50% of inhabitants. 98 municipalities are covered by an approved natural hazard prevention plan.

Seismicity Zones

Number of municipalities in each zone of the regulatory seismic zoning (from 1, very low, to 5, high).

Natural Disasters Declared Since 1982

Declarations per five-year period.

Most Widespread Events

• 1999Floods and Mudflows · 25 December 1999385 municipalities
• 1999Ground Movements · 25 December 1999385 municipalities
• 1995Floods and Mudflows · 17 January 199559 municipalities
• 1993Floods and Mudflows · 10 January 199357 municipalities
• 2018Floods and Mudflows · 11 June 201828 municipalities
• 2018Floods and Mudflows · 12 June 201824 municipalities

Most Frequently Affected Municipalities

• 25Val-au-Perche
• 13Domfront en Poiraie
• 13Tourouvre au Perche
• 12Ceton
• 12Vimoutiers
• 11Rémalard en Perche
• 10Alençon
• 10Sablons sur Huisne

Hazards Listed by Municipality

Number of municipalities exposed to each natural hazard according to the departmental major risks file.

Hazards at a specific address on Géorisques