Map visualisation service (WMS) of the dataset: N_ZONE_ALEA_PPRN_20140203_S_032

The mapping of the hazard removal swelling of the clays in the municipality of Castillon-Massas in the department of Gers is extracted from the departmental cartography resulting from the BRGM. This mapping is a zoning of the probability of occurrence of the phenomenon of withdrawal-swelling of clay fields. A susceptibility map was first drawn up on the basis of purely physical criteria by BRGM from the geological maps of the department, which were interpreted taking into account the following factors for each geological formation: — the proportion of clay material within the formation (Lithological analysis); — the proportion of inflating minerals in the clay phase (mineralogical composition); — the geotechnical behaviour of the material. For each of the clay formations identified, the hazard level is ultimately the result of the level of susceptibility thus obtained with the density of shrinkage swelling, reported to 100 km² of outcropping area actually urbanised.