Subsoil and ground of Paris’s 1st arrondissement
No quarry recorded Paris 75001
The 1st arrondissement (Louvre, Tuileries, Les Halles) lies on an ancient alluvial terrace on the edge of the Seine, urbanised and filled in for more than two thousand years (superimposed Gallo-Roman, medieval and modern levels). No underground quarry is recorded by the IGC (Paris quarry inspectorate) for this area.
What public data say about the 1st
| Underground quarries recorded by the IGC (Paris quarry inspectorate) | None |
|---|---|
| Nature of the ground | Former alluvial terrace (right bank) |
| Foundation issue | Historic urban subsoil: anthropogenic fill (demolition material, former cellars, remains) can be several metres thick in an uneven manner. A G1 geotechnical study is recommended before any project to check the ground’s bearing capacity and uniformity. |
Ground, fill and clay shrink-swell
The 1st arrondissement (Louvre, Tuileries, Les Halles) lies on an ancient alluvial terrace on the edge of the Seine, urbanised and filled in for more than two thousand years (superimposed Gallo-Roman, medieval and modern levels). No underground quarry is recorded by the IGC (Paris quarry inspectorate) for this area.
Historic urban subsoil: anthropogenic fill (demolition material, former cellars, remains) can be several metres thick in an uneven manner. A G1 geotechnical study is recommended before any project to check the ground’s bearing capacity and uniformity.
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 1st before purchase or works
- 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 1st arrondissement?
No former underground quarry is recorded by the IGC (Paris quarry inspectorate) for the 1st arrondissement. Areas of former quarries within Paris are concentrated in the south (5th, 6th, 12th, 13th, 14th, 15th, 16th, in Lutetian coarse limestone) and in the north-east (10th, 18th, 19th, 20th, in gypsum). This does not mean there are no ground issues: the 1st falls under the « ground and foundations » section.
Is a soil study still needed in the 1st?
Yes, whenever there is a construction, extension or underpinning project. Historic urban subsoil: anthropogenic backfill (demolition material, former cellars, remains) can be several metres thick in a heterogeneous way. A G1 geotechnical study is recommended before any project to check the load-bearing capacity and homogeneity of the ground.
Why does the 1st’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 1st 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
- Subsoil of the 2nd arrondissement
- Subsoil of the 3rd arrondissement
- Subsoil of the 4th arrondissement
- Subsurface of the 5th arrondissement
- See the 20 arrondissements
Sources
- Wikipedia — Paris, Geology section
- City of Paris — Everything you need to know about the subsurfaces
- BRGM — Why is there no map of the clay shrink-swell hazard for Paris?
- Géorisques — Clay shrink-swell, 2026 version (data)
- Géorisques — Underground cavities (data)
- City of Paris — the IGC (Paris quarry inspectorate) location
- City of Paris — Known areas of former quarries (IGC)
Page updated on 11 September 2026.