Dataset Direct Download Service (WFS): N_ZONE_ALEA_PPRN_20140256_S_032

The mapping of the hay removal of clays in the municipality of Marciac in the Gers department is extracted from the departmental mapping from the BRGM. This mapping is a zoning of the probability of occurrence of the phenomenon of shrink-inflating of clay soils. A susceptibility map was first drawn up on the basis of purely physical criteria by the 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 (lithic analysis); — the proportion of blowing minerals in the clay phase (mineralogical composition); — the geotechnical behavior 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 sinister swelling, reported to 100 km² of actual urbanised outcropping surface.热尔省马尔西亚克市范围内的黏土收缩-膨胀现象分布图，源自法国地质矿产调查局（Bureau de Recherches Géologiques et Minières，BRGM）编制的全省分布图。该分布图为黏土收缩-膨胀现象发生概率的分区图。 法国地质矿产调查局（BRGM）最初基于纯物理标准，依托该省地质图编制了易发性图（susceptibility map）；该省地质图的解译过程针对每个地质地层，综合考量了以下因素： — 地层内黏土物质的占比（岩相分析）； — 黏土相内膨胀性矿物的占比（矿物组成分析）； — 该物质的岩土工程特性。 针对每一个已识别的黏土地层，最终的灾害等级由上述易发性等级结合灾害性膨胀密度计算得出，统计基准为每100平方公里实际出露的城市化地表。