Quarry risk and the subsoil of Paris’s 20 arrondissements
Twelve Paris arrondissements are affected by former underground quarries: seven in Lutetian coarse limestone in the south (5th, 6th, 12th, 13th, 14th, 15th, 16th) and four in Antediluvian gypsum in the north-east (10th, 18th, 19th, 20th), plus the 7th on the edge of the southern network. The other eight have no quarry recorded by the IGC (Paris quarry inspectorate), but are nevertheless covered by the ground and foundations section. Each page sets out the available public data, the documented history and the steps to take.
| Arrondissement | Quarry risk | Rock | Network or nature of the ground |
|---|---|---|---|
| 1st arrondissement | No quarry recorded | — | Former alluvial terrace (right bank) |
| 2nd arrondissement | No quarry recorded | — | Old terrace / Tertiary plateau |
| 3rd arrondissement | No quarry recorded | — | Former terrace, northern edge of the Marais |
| 4th arrondissement | No quarry recorded | — | Former oxbow lake of the Seine (Marais, Îles) |
| 5th arrondissement | High | Coarse limestone | Grand Réseau Sud (GRS) |
| 6th arrondissement | High | Coarse limestone | Grand Réseau Sud (GRS) |
| 7th arrondissement | Moderate | Coarse limestone | Left-bank sector (GRS boundary) |
| 8th arrondissement | No quarry recorded | — | Former alluvial terrace (right bank) |
| 9th arrondissement | No quarry recorded | — | Southern edge of Montmartre hill |
| 10th arrondissement | Moderate | Antediluvian gypsum | Gypsum quarries (north-east) |
| 11th arrondissement | No quarry recorded | — | Plateau, bordering the Belleville gypsum sector |
| 12th arrondissement | High | Coarse limestone | Grand Réseau Sud (GRS) |
| 13th arrondissement | High | Coarse limestone | Network « the 13th » (thirteenth) |
| 14th arrondissement | Very High | Coarse limestone | Grand Réseau Sud (GRS) |
| 15th arrondissement | High | Coarse limestone | Grand Réseau Sud (GRS) |
| 16th arrondissement | Moderate | Coarse limestone | Réseau de Chaillot (rive droite) |
| 17th arrondissement | No quarry recorded | — | Tertiary plateau / terrace |
| 18th arrondissement | Moderate | Antediluvian gypsum | Gypsum quarries (Montmartre hill) |
| 19th arrondissement | High | Antediluvian gypsum | Gypsum quarries (Buttes-Chaumont) |
| 20th arrondissement | Moderate | Antediluvian gypsum | Gypsum quarries (east) |
Key points on the Paris subsoil
- More than 3 000 hectares of land, spread across 70 municipalities, are affected overall by the presence of former quarries in Île-de-France.
- Within Paris proper, areas of former quarries (760–770 ha) are concentrated in the southern arrondissements: 5th, 6th, 12th, 13th, 14th, 15th and 16th — almost all in Lutetian coarse limestone.
- The 14th arrondissement is Paris’s most undermined (~260 ha of Lutetian coarse limestone). The Grand Réseau Sud (5th, 6th, 14th, 15th) totals ~508 ha and 200 km of galleries.
- Gypsum quarries, which are more dangerous because the rock is soluble in water, mainly affect northern Paris (10th, 18th, 19th, 20th — 65 ha). The dissolution of Antediluvian gypsum remains monitored by the IGC (Paris quarry inspectorate) via its network of piezometers.
- Paris records around ten incidents a year linked to the deterioration of former galleries, including one collapse on average. In 2017, the IGC (Paris quarry inspectorate) responded to 65 incidents; in 2023, 211 inspections and 106 interventions; in 2024, 287 inspections in quarries beneath public land. Consolidation work costs the City €3 to €6m/year.
- The Paris subsoil also contains the world’s largest ossuary: the catacombs, designated « Municipal Ossuary » on 7 April 1786 in former Tombe-Issoire quarries (14th), and open to the public from 1809. Around 1.7 km can be visited out of the ~280–300 km of underground network.
- Quarry-related problems are not recognised as « natural disaster »: in the event of collapse, the filling works (40 000 to 200 000 €) are the responsibility of the owners.
Regulatory framework
- Article R111-3 of the Town Planning Code
- Most quarry or gypsum-dissolution perimeters were defined by the préfets under former Article R111-3 of the Urban Planning Code. These zonings regulate planning permissions in at-risk areas. Source: City of Paris — Known areas of former quarries (IGC) · Légifrance / Pappers — Article R111-3 of the Town Planning Code
- Zoning appended to the PLU / PPRN
- In Paris, regulatory zoning is divided into: zoning appended to the PLU (in green), R111-3 zoning constituting a PPR (in orange) and approved PPRs (in blue and red). Source: City of Paris — IGC activity report (R111-3/PPR zoning)
- Referral to the IGC (Paris quarry inspectorate) for permits
- Prefectoral and inter-prefectoral orders require referral to the IGC (Paris quarry inspectorate) for any planning permission in areas at risk from former quarries. Source: City of Paris — Known areas of former quarries (IGC)
- Cavity data not published on Géorisques
- For départements 75, 78, 91, 92, 93, 94 and 95, cavity data are NOT available on the Géorisques portal. The information can be consulted from the IGC (Paris quarry inspectorate) (75, 92, 93, 94) or the competent interdepartmental service. Source: Géorisques — Underground cavities (data)
Page updated on 11 September 2026.