Morbihan

Recorded Natural Hazards (Géorisques)

It has 249 municipalities and 783,390 inhabitants. Under the seismic zoning in force since 2011, its highest seismicity is low (zone 2 of 5). A natural disaster has been declared 1,490 times since 1982 (one declaration per municipality and decree), mostly for floods (910) and ground movements (251). The most recent was signed on 22 June 2025. 203 municipalities have a high radon potential (category 3), home to 92% of inhabitants. 90 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

• 1999Ground Movements · 25 December 1999250 municipalities
• 1999Floods and Mudflows · 25 December 1999250 municipalities
• 1987Storms · 15 October 1987250 municipalities
• 1995Floods and Mudflows · 17 January 199589 municipalities
• 1995Floods and Mudflows · 17 January 199563 municipalities
• 1988Floods and Mudflows · 15 January 198861 municipalities

Most Frequently Affected Municipalities

• 16Baud
• 13Hennebont
• 13Pontivy
• 12Loyat
• 12Missiriac
• 12Peillac
• 12Ploërmel
• 12Saint-Laurent-sur-Oust

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