Gan: geology and natural hazards

Seismic zone

4 of 5 (medium)

Radon potential

Category 1 of 3 (low potential)

Recognised natural disasters

23 since 1982

Underground cavities recorded

None

Ground movements recorded

6

Risk prevention plans

1

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
• Séisme
• Transport de marchandises dangereuses

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

• Inondations et/ou coulées de boue: 15
• Sécheresse: 4
• Mouvement de terrain: 3
• Chocs mécaniques liés à l’action des vagues: 2
• Tempête: 2
• Grêle: 1

1. Sécheresse

   Event from 31/12/2024 to 30/12/2025, order published in the Journal officiel on 26/02/2026.

2. Sécheresse

   Event from 01/07/2022 to 31/12/2022, order published in the Journal officiel on 03/05/2023.

3. Inondations et/ou coulées de boue

   Event from 09/12/2021 to 12/12/2021, order published in the Journal officiel on 17/12/2021.

4. Inondations et/ou coulées de boue

   Event on 16/07/2018, order published in the Journal officiel on 20/10/2018.

5. Inondations et/ou coulées de boue

   Event from 12/06/2018 to 13/06/2018, order published in the Journal officiel on 15/08/2018.

6. Mouvement de terrain

   Event from 12/06/2018 to 13/06/2018, order published in the Journal officiel on 14/02/2019.

7. Mouvement de terrain

   Event from 25/02/2016 to 29/02/2016, order published in the Journal officiel on 20/10/2016.

8. Inondations et/ou coulées de boue

   Event on 01/07/2014, order published in the Journal officiel on 06/01/2015.

9. Inondations et/ou coulées de boue

   Event from 24/01/2014 to 25/01/2014, order published in the Journal officiel on 26/04/2014.

10. Mouvement de terrain

    Event from 20/08/2010 to 21/08/2010, order published in the Journal officiel on 21/08/2011.

11. Chocs mécaniques liés à l’action des vagues, Inondations et/ou coulées de boue

    Event from 24/01/2009 to 27/01/2009, order published in the Journal officiel on 29/01/2009.

12. Inondations et/ou coulées de boue

    Event on 12/06/2008, order published in the Journal officiel on 13/08/2008.

13. Inondations et/ou coulées de boue

    Event on 25/05/2007, order published in the Journal officiel on 10/07/2007.

14. Chocs mécaniques liés à l’action des vagues

    Event from 25/12/1999 to 29/12/1999, order published in the Journal officiel on 30/12/1999.

15. Inondations et/ou coulées de boue

    Event on 25/08/1997, order published in the Journal officiel on 16/11/1997.

16. Inondations et/ou coulées de boue

    Event from 08/08/1992 to 09/08/1992, order published in the Journal officiel on 08/07/1993.

17. Sécheresse

    Event from 01/01/1991 to 31/12/1996, order published in the Journal officiel on 01/07/1998.

18. Inondations et/ou coulées de boue

    Event on 21/05/1990, order published in the Journal officiel on 19/12/1990.

19. Sécheresse

    Event from 01/06/1989 to 31/12/1990, order published in the Journal officiel on 27/12/1991.

20. Inondations et/ou coulées de boue

    Event from 26/08/1983 to 28/08/1983, order published in the Journal officiel on 22/09/1983.

21. Inondations et/ou coulées de boue, Tempête, Grêle

    Event from 17/07/1983 to 18/07/1983, order published in the Journal officiel on 11/09/1983.

22. Inondations et/ou coulées de boue

    Event from 17/07/1983 to 18/07/1983, order published in the Journal officiel on 08/10/1983.

23. Inondations et/ou coulées de boue, Tempête

    Event from 06/11/1982 to 10/11/1982, order published in the Journal officiel on 02/12/1982.

Seismic zone

Zone 4 of 5: medium. This regulatory zoning, in force since 2011, sets the rules for earthquake-resistant construction.

Radon potential

Category 1 of 3: low potential. The geological formations have the lowest uranium content. Radon is a naturally occurring radioactive gas that can build up in poorly ventilated rooms.

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

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

No underground cavity recorded (quarries, cellars, military works, natural cavities…).

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

See cavities and ground movements on the map

• PPRi - GAN (révision)

  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.

• Bosdarros (64)
• Uzos (64)
• Rontignon (64)
• Narcastet (64)
• Mazères-Lezons (64)
• Gelos (64)
• Jurançon (64)
• Baliros (64)

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 02/11/2026. 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.