Loire-Atlantique

Recorded Natural Hazards (Géorisques)

It has 207 municipalities and 1,487,570 inhabitants. Under the seismic zoning in force since 2011, its highest seismicity is moderate (zone 3 of 5). A natural disaster has been declared 1,304 times since 1982 (one declaration per municipality and decree), mostly for floods (843) and ground movements (248). The most recent was signed on 23 March 2025. 166 municipalities have a high radon potential (category 3), home to 78% of inhabitants. 64 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 1999207 municipalities
• 1999Ground Movements · 25 December 1999207 municipalities
• 2024Floods and Mudflows · 17 June 202446 municipalities
• 1983Hail · 18 July 198340 municipalities
• 1983Storms · 18 July 198340 municipalities
• 1983Floods and Mudflows · 18 July 198340 municipalities

Most Frequently Affected Municipalities

• 17Les Moutiers-en-Retz
• 15Nantes
• 15Orvault
• 15Saffré
• 15Thouaré-sur-Loire
• 14Gorges
• 14Le Landreau
• 14Vallons-de-l'Erdre

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