Quarries and subsoil of Paris’s 7th arrondissement

Q: Are there underground quarries beneath Paris’s 7th arrondissement?

Yes. The 7th arrondissement is listed in public data from the IGC (Paris quarry inspectorate) as an area concerned by the “Left Bank sector (GRS boundary)” network, in rock of the Lutetian coarse limestone type. The selected risk level is “Moderate”, with medium confidence in the area’s classification. The 7th is included in the Institut Paris Région study as a Left Bank area affected by quarries, but is not detailed individually by the IGC in the official limestone report (5th,6th,12th,13th,14th,15th,16th). Medium confidence.

Q: How can I find out whether my exact address in the 7th 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.

Q: Why do cavity data for the 7th 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.

Q: Is the 7th’s quarry risk 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.

Moderate risk Paris 75007

The 7th arrondissement (Invalides, Gros-Caillou, Champ-de-Mars) is among the Left Bank areas affected by former quarries, according to Institut Paris Région. However, it is not individually detailed by the IGC (Paris quarry inspectorate) in the official overview of Lutetian coarse limestone (5th, 6th, 12th, 13th, 14th, 15th, 16th). The risk is present but less documented: an official information request to the IGC (Paris quarry inspectorate) (10 €, response time under 8 days) can remove uncertainty for a specific address.

What the public data say about the 7th

Summary of the subsoil of Paris’s 7th arrondissement, based on compiled public data (IGC, Institut Paris Région, BRGM).
Underground network	Left-bank sector (GRS boundary)
Mined rock	Lutetian coarse limestone
Undermined area	Not individually quantified by the IGC (Paris quarry inspectorate).
Galleries	Included in the southern network (length not detailed).
Selected risk level	Moderate
Confidence in the classification	average
Nature of the ground	Limestone plateau to the east, alluvial plain to the west
Foundation issue	Heterogeneous area: load-bearing limestone ground to the east, loose alluvium and fill near the Seine to the west, which may justify special foundations (wells, micropiles). A G1 geotechnical study followed by G2 is strongly recommended.

Sensitive areas of the 7th

Invalides, Gros-Caillou, Saint-Thomas-d’Aquin areas
Listed as a quarry area by Institut Paris Région, not detailed by the IGC (Paris quarry inspectorate) in the official limestone report

Ground, fill and clay shrink-swell

The 7th arrondissement combines a plateau of Lutetian coarse limestone on the Invalides side (edge of the Grand Réseau Sud) and an alluvial plain on the Champ-de-Mars / Grenelle side, on the edge of the Seine, where infill and modern alluvial deposits may exceed several metres in thickness.

Heterogeneous area: load-bearing limestone ground to the east, loose alluvium and fill near the Seine to the west, which may justify special foundations (wells, micropiles). A G1 geotechnical study followed by G2 is strongly recommended.

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 7th before purchase or works

Medium confidence: the 7th is not detailed individually by the IGC (Paris quarry inspectorate). An official information request to the IGC (10 €, < 8 days) is recommended to remove the uncertainty, particularly towards Gros-Caillou and around Champ-de-Mars.

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 7th arrondissement?

Yes. The 7th arrondissement is listed in public data from the IGC (Paris quarry inspectorate) as an area concerned by the “Left Bank sector (GRS boundary)” network, in rock of the Lutetian coarse limestone type. The selected risk level is “Moderate”, with medium confidence in the area’s classification. The 7th is included in the Institut Paris Région study as a Left Bank area affected by quarries, but is not detailed individually by the IGC in the official limestone report (5th,6th,12th,13th,14th,15th,16th). Medium confidence.

How can I find out whether my exact address in the 7th 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 do cavity data for the 7th 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 the 7th’s quarry risk 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.