Manche

Recorded Natural Hazards (Géorisques)

It has 445 municipalities and 497,522 inhabitants. Under the seismic zoning in force since 2011, its highest seismicity is low (zone 2 of 5). A natural disaster has been declared 2,462 times since 1982 (one declaration per municipality and decree), mostly for floods (1,252) and ground movements (552). The most recent was signed on 23 March 2025. 215 municipalities have a high radon potential (category 3), home to 62% of inhabitants. 87 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 1999445 municipalities
• 1999Ground Movements · 25 December 1999445 municipalities
• 1987Storms · 15 October 1987445 municipalities
• 1983Snow Load · 7 February 1983149 municipalities
• 1995Floods and Mudflows · 17 January 1995129 municipalities
• 1984Floods and Mudflows · 22 November 1984103 municipalities

Most Frequently Affected Municipalities

• 18La Hague
• 17Picauville
• 16Carentan-les-Marais
• 15Port-Bail-sur-Mer
• 14Valognes
• 13La Haye
• 13Montmartin-sur-Mer
• 12Barneville-Carteret

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