Quarries and subsoil of Paris’s 14th arrondissement

Very high risk Paris 75014

The 14th arrondissement is the most extensively undermined in Paris: around 260 hectares of former Lutetian coarse limestone quarries. It contains the entrance to the catacombs (place Denfert-Rochereau), the former headquarters of the IGC (Paris quarry inspectorate) (barrière d’Enfer) and the Alésia, Montparnasse and Parc Montsouris areas. Prefectoral orders made under Article R111-3 of the town planning code are numerous there. This concentration of risks in the 14th makes it the capital’s most exposed area: a subsoil pre-assessment is particularly recommended before any purchase or project.

What the public data say about the 14th

Overview of the subsoil of Paris’s 14th arrondissement, based on compiled public data (IGC, Institut Paris Région, BRGM).
Underground network	Grand Réseau Sud (GRS)
Mined rock	Lutetian coarse limestone
Undermined area	~260 hectares — the most undermined area in Paris.
Galleries	Included in the GRS’s ~200 km of galleries.
Selected risk level	Very High
Confidence in the classification	high
Nature of the ground	Limestone plateau (Paris’s most undermined)
Foundation issue	Limestone ground is generally load-bearing outside a proven cavity area; the main risk remains related to quarries, not clay shrink-swell. A G2 geotechnical study is recommended given the density of former galleries.

Sensitive areas of the 14th

Alésia, Montparnasse, Parc Montsouris, Denfert-Rochereau areas
Catacombs entrance, former headquarters of the IGC (Paris quarry inspectorate) (Barrière d’Enfer)
Numerous R111-3 prefectural orders

Documented events in the 14th

December 1774
Subsidence of route d’Orléans
Barrière d’Enfer (5th/14th)
Widespread subsidence of the route d’Orléans over more than 300 metres in length. This event triggered the creation of the IGC (Paris quarry inspectorate) in 1777.
Source: Institut Paris Région — Underground risk study (quarries) · Annales des Mines — The Quarry Service
1774 (detail)
Collapse on rue d’Enfer (300 m)
rue d’Enfer / av. Denfert-Rochereau (5th/14th)
On 17 December 1774, a quarry excavation caused the collapse of rue d’Enfer (now avenue Denfert-Rochereau). Nearly 300 metres of road disappeared into a considerable excavation. The direct catalyst for the creation of the IGC (Paris quarry inspectorate).
Source: Le Figaro — The burdensome legacy of Paris’s Swiss-cheese subsurfaces · Catacombs of Paris (official website) — History of the site
7 April 1786
Consecration of the municipal ossuary
Tombe-Issoire (14th)
Establishment of the « Municipal Ossuary » in former limestone quarries at Tombe-Issoire (14th), beneath place Denfert-Rochereau. Creation of the Paris catacombs, the world’s largest ossuary (~1,7 km open to visitors across a ~280–300 km network).
Source: Catacombs of Paris (official website) — History of the site · Wikipédia — Paris Catacombs
2017
The IGC (Paris quarry inspectorate) leaves the barrière d’Enfer
Barrière d’Enfer (14th)
The eastern pavilion of Barrière d’Enfer, which housed the IGC (Paris quarry inspectorate), is closing. Temporary relocation to place de la Porte-de-Vanves.
Source: Wikipedia — the IGC (Paris quarry inspectorate)

Ground, fill and clay shrink-swell

The 14th arrondissement lies on Paris’s most undermined Lutetian coarse limestone plateau (see quarries section), in a generally high position with few alluvial areas.

Limestone ground is generally load-bearing outside a proven cavity area; the main risk remains related to quarries, not clay shrink-swell. A G2 geotechnical study is recommended given the density of former galleries.

Unlike almost all French municipalities, inner Paris has no official mapping of the clay shrink-swell hazard (RGA). The BRGM explains this explicitly: the Paris subsoil is largely made up of reworked and artificial materials (backfill, infilled former quarries), which does not correspond to the standard methodology for this mapping — centred on detached houses, which are in the minority in Paris. This does not mean that there is no risk of differential settlement, but that no official area-by-area study exists for the capital: a ground investigation remains the only reliable way to assess a specific plot before purchase or construction.

Your procedures in the 14th before purchase or works

Very high risk: this area contains the greatest number of undermined zones in Paris. Consultation with the IGC (Paris quarry inspectorate) is essential, a G1-G2 geotechnical study is recommended, and a statutory risk statement (ERP) is available via Errial. Check whether an approved natural risk prevention plan (PPRN) may be in place.

IGC (Paris quarry inspectorate) information sheet — the authoritative source on the condition of the parcel’s subsoil: €10, issued within 8 days, via the City of Paris online service.
Statutory risk statement (ERP) — mandatory for sale and letting, generated from Errial; note, it does not return cavity data in Paris.
geotechnical survey — G1 mission before purchasing a building plot, G2 AVP before a construction or underpinning project.
Referral to the IGC (Paris quarry inspectorate) for planning — prefectoral orders require it to be consulted for any planning permission in a quarry-risk area.

Frequently asked questions

Are there underground quarries beneath Paris’s 14th arrondissement?

Yes. The 14th arrondissement is listed in the public data of the IGC (Paris quarry inspectorate) as an area affected by the network « Grand Réseau Sud (GRS) », in Lutetian coarse limestone. The assigned risk level is « Very High », with high confidence in the sector’s classification. Paris’s most extensively undermined arrondissement. Former headquarters of the IGC (Paris quarry inspectorate) in the east pavilion of the barrière d’Enfer (until 2017). Denfert-Rochereau / Alésia sector.

How can I tell whether my specific address in the 14th is in an undermined area?

Quarry zoning must be read at plot level rather than arrondissement level. There are two options: the official information sheet from the IGC (Paris quarry inspectorate), at €10 and issued within 8 days, which is the legally binding source; and Sous-sol Paris’s instant pre-assessment, at €15, which matches your address against public data and immediately provides you with a readable report, including the steps to take. This pre-assessment is for information only and does not replace the IGC information sheet, the statutory risk statement (ERP), or a geotechnical study.

Why does the 14th’s cavity data not appear on Géorisques?

Because for départements 75, 78, 91, 92, 93, 94 and 95, cavity data are not published on the Géorisques portal: they can be consulted with the IGC (Paris quarry inspectorate) for Paris and the inner suburbs, or with the relevant interdepartmental service. This is why a standard statutory risk statement (ERP) remains silent on Paris quarries and gypsum.

Is quarry risk in the 14th covered by insurance?

Disorders linked to former quarries do not fall under the « natural disaster » scheme. In the event of collapse, infill works, estimated at 40 000 to 200 000 €, remain the responsibility of the owners. This is what makes checking before purchase essential.

Other arrondissements

Sources

Page updated on 11 September 2026.