Dataset Direct Download Service (WFS): Map of seismic hazard in the department of Maine-et-Loire(49)

Seismicity is not evenly distributed throughout the metropolitan area. In order to make the appropriate arrangements for the degree of exposure of each municipality, the legislator relies on a national seismic hazard mapping (seismic zoning). This mapping is proposed on the basis of a simplified classification at the level of the entire national territory (metropolicy and Antilles) and covering all the municipalities. This zoning is applicable to buildings and structures built to accommodate populations, to perform socio-economic functions or to maintain the functioning of the State. “Normal hazard” buildings are classified by size categories whose crossing with the seismicity zone in which they are located determines the seismic requirements to be complied with (more information). The approach is different for nuclear installations. The seismic stress likely to affect them is defined on the basis of specific studies carried out for each site, in order to take account of their particular geological and seismological conditions. On 1 May 2011, the new seismic zoning of France for conventional construction at “normal risk” entered into force, following the Order of 22 October 2010 “on the classification and rules of seismic construction applicable to buildings of the class of the normal risk” and Decrees No 2010-1254 on the prevention of seismic risk and No. 2010-1255 on the delimitation of seismic zones in the French territory. The new mapping promulgated in 2010 (Decree of 22 October 2010 and entered into force on 1 May 2011) is based on a so-called probabilistic assessment of seismic hazard. This approach aims at estimating the vibrational seismic movement likely to be achieved or exceeded based on a fixed probability over a given period of time, e.g. 10 % over a 50-year period for conventional construction. This type of approach allows to take into account a very wide range of seismic scenarios weighted according to their probability of occurrence. IRSN participated in the development of this new map of the seismic hazard of France, as an expert for the Ministry of the Environment. This zoning divides the French territory into 5 areas of seismicity (very small, weak, moderate, medium, strong). In zones 2 to 5, seismic construction rules apply to “normal risk” buildings and bridges. This concerns about 21 000 municipalities instead of 5,000 previously (areas Ia, II and III). In addition, the Order of 24 January 2011 (amending the Order of 4 October 2010 on the prevention of accidental risks in installations classified for the protection of the environment subject to authorisation) lays down the seismic rules applicable to certain classified installations (excluding nuclear installations which are dealt with by a specific regulation — RFS 2001-01) on the basis of this new seismic zoning of France.地震活动在法国本土并非均匀分布。为合理规划各市镇的抗震设防烈度，立法机构采用了国家地震危险性区划图（地震区划）。该区划基于覆盖法国全境（本土及安的列斯群岛）的简化分类标准制定，涵盖所有市镇。 该地震区划适用于用于人口安置、承担社会经济职能或保障国家运行的建筑与构筑物。"常规风险"建筑按规模类别进行分级，结合其所处地震活动带，即可确定需遵循的抗震设计要求（详见更多说明）。核设施的抗震设计要求则采用不同的确定方式：其需承受的地震作用需基于针对每个场址开展的专项研究确定，以充分考虑其独特的地质与地震学条件。 2011年5月1日，法国针对"常规风险"民用建筑的新版地震区划正式生效，其制定依据为2010年10月22日发布的《关于常规风险等级建筑抗震分类与设计规则的条例》，以及2010年第2010-1254号《地震风险防控法令》与第2010-1255号《法国境内地震带划界定令》。 2010年颁布、2011年5月1日正式施行的新版区划图，采用了所谓的地震危险性概率评估方法。该方法旨在基于给定时间段内的固定概率，估算可能发生或超越的地震振动强度，例如针对常规民用建筑，采用50年内超越概率为10%的标准。此类方法可综合考虑多种地震情景，并依据其发生概率赋予相应权重。法国核安全与辐射防护研究所（IRSN）作为法国环境部的专家机构，参与了法国新版地震危险性区划图的编制工作。 该地震区划将法国全境划分为5个地震活动等级区域（极低、弱、中、强、极强）。在2至5级区域内，常规风险建筑与桥梁需遵循抗震设计规则。受此规则约束的市镇数量由此前的约5000个（对应Ia、II、III级区域）增至约21000个。 此外，2011年1月24日发布的《关于修订2010年10月4日〈需经审批的环保类设施意外风险防控条例〉的政令》，依据法国新版地震区划，规定了适用于部分分类设施的抗震设计规则（核设施除外，其抗震要求由专项法规RFS 2001-01另行规定）。