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Montarnaud: geology and natural hazards

What public services say about the ground beneath the commune (population 4,208) and the hazards it faces: natural disasters, earthquakes, radon, cavities, clays, groundwater and rocks.

Hazard names and other data are quoted as their producers publish them, in French.

Explore the commune on the map

Montarnaud at a glance

Seismic zone
2 of 5 (low)
Radon potential
Category 2 of 3 (low potential, with aggravating factors)
Recognised natural disasters
25 since 1982
Underground cavities recorded
5
Ground movements recorded
2
Risk prevention plans
1

Hazards listed by the French State

Natural and technological hazards to which the commune is exposed, according to the national GASPAR database.

  • Inondation: par une crue torrentielle ou à montée rapide de cours d’eau
  • Mouvement de terrain: affaissements et effondrements d’origine anthropique (anciennes carrières souterraines, hors mines), eboulement ou chutes de pierres et de blocs, glissement de terrain, tassements différentiels
  • Séisme
  • Feu de forêt
  • Radon
  • Transport de marchandises dangereuses

Recognised natural disasters

25 events recognised as a natural disaster by ministerial order since 1982.

  • Inondations et/ou coulées de boue: 16
  • Sécheresse: 9
  • Glissement de terrain: 1
  • Tempête: 1

  1. Inondations et/ou coulées de boue

    Event from 18/12/2025 to 27/12/2025, order published in the Journal officiel on 17/03/2026.

  2. Inondations et/ou coulées de boue

    Event from 22/10/2019 to 23/10/2019, order published in the Journal officiel on 31/10/2019.

  3. Sécheresse

    Event from 01/07/2019 to 30/09/2019, order published in the Journal officiel on 12/06/2020.

  4. Sécheresse

    Event from 01/07/2017 to 30/09/2017, order published in the Journal officiel on 20/10/2018.

  5. Inondations et/ou coulées de boue

    Event on 14/09/2016, order published in the Journal officiel on 27/01/2017.

  6. Inondations et/ou coulées de boue

    Event from 06/10/2014 to 07/10/2014, order published in the Journal officiel on 07/11/2014.

  7. Inondations et/ou coulées de boue

    Event from 29/09/2014 to 30/09/2014, order published in the Journal officiel on 07/11/2014.

  8. Inondations et/ou coulées de boue

    Event from 17/09/2014 to 19/09/2014, order published in the Journal officiel on 07/11/2014.

  9. Inondations et/ou coulées de boue

    Event from 04/11/2011 to 06/11/2011, order published in the Journal officiel on 19/11/2011.

  10. Sécheresse

    Event from 01/07/2009 to 30/09/2009, order published in the Journal officiel on 13/01/2011.

  11. Inondations et/ou coulées de boue

    Event on 02/11/2008, order published in the Journal officiel on 22/04/2009.

  12. Sécheresse

    Event from 01/07/2007 to 30/09/2007, order published in the Journal officiel on 13/08/2008.

  13. Sécheresse

    Event from 01/01/2007 to 31/03/2007, order published in the Journal officiel on 13/08/2008.

  14. Inondations et/ou coulées de boue

    Event from 06/09/2005 to 07/09/2005, order published in the Journal officiel on 14/10/2005.

  15. Sécheresse

    Event from 01/01/2005 to 31/03/2005, order published in the Journal officiel on 22/02/2008.

  16. Inondations et/ou coulées de boue

    Event from 06/10/2004 to 07/10/2004, order published in the Journal officiel on 31/05/2005.

  17. Inondations et/ou coulées de boue

    Event on 03/12/2003, order published in the Journal officiel on 26/02/2004.

  18. Inondations et/ou coulées de boue

    Event on 22/09/2003, order published in the Journal officiel on 20/12/2003.

  19. Inondations et/ou coulées de boue

    Event from 11/12/2002 to 12/12/2002, order published in the Journal officiel on 09/03/2003.

  20. Sécheresse

    Event from 01/01/2002 to 31/03/2002, order published in the Journal officiel on 19/10/2003.

  21. Sécheresse

    Event from 01/03/1998 to 30/06/1999, order published in the Journal officiel on 29/12/2000.

  22. Inondations et/ou coulées de boue

    Event from 17/10/1994 to 28/10/1994, order published in the Journal officiel on 25/11/1994.

  23. Sécheresse

    Event from 01/01/1991 to 31/12/1991, order published in the Journal officiel on 29/12/2000.

  24. Inondations et/ou coulées de boue, Glissement de terrain

    Event from 04/11/1984 to 15/11/1984, order published in the Journal officiel on 29/03/1985.

  25. Tempête, Inondations et/ou coulées de boue

    Event from 06/11/1982 to 10/11/1982, order published in the Journal officiel on 19/11/1982.

Earthquakes and radon

Seismic zone

Zone 2 of 5: low. This regulatory zoning, in force since 2011, sets the rules for earthquake-resistant construction.

Radon potential

Category 2 of 3: low potential, with aggravating factors. Geological features (faults, mine workings, thermal springs) can make it easier for radon to reach buildings. Radon is a naturally occurring radioactive gas that can build up in poorly ventilated rooms.

Beneath the town hall

What BRGM maps say at the town hall. They describe that single point: elsewhere in the commune, the ground may be quite different.

  • Shrink-swell clays

  • Rising groundwater

  • Underground cavities

  • Ground movements

  • Earthquakes

  • Nature of the ground

Cavities and ground movements

Recorded across the whole commune by BRGM, in its national databases of underground cavities and ground movements.

5 underground cavities recorded (quarries, cellars, military works, natural cavities…).

2 ground movements recorded (landslides, rockfalls, collapses, mudflows…).

See cavities and ground movements on the map

Risk prevention plans

  • PPRI_Mosson_HautBassin

    Natural risk prevention plan, under revision.

The zoning and regulations of each plan, which may prohibit or restrict building, can be consulted at the town hall and on Géorisques.

Nearby communes

Sources and limitations

Listed hazards, natural disasters, seismic zoning, radon potential, cavities, ground movements and prevention plans: Géorisques, published by the French ministry for the ecological transition, under Licence Ouverte Etalab 2.0, data accessed on 03/11/2026. Summary beneath the town hall: BRGM map services, queried when the page is displayed. List of communes and populations: API Découpage administratif (geo.api.gouv.fr), d’après le code officiel géographique de l’Insee, version of 30/10/2026.

This information reflects the state of knowledge at the scale of the commune or of a single point. It replaces neither a soil survey nor the official risk statement (état des risques) required for a sale or a rental, which is drawn up on the official French government service.