Plan to prevent the natural risks of landslides — Commune de Montastruc — Zone d’alas — Department of Tarn-et-Garonne.

Area exposed to one or more hazards represented on the hazard map used for risk analysis of the RPP. The hazard map is the result of the study of hazards, the objective of which is to assess the intensity of each hazard at any point in the study area. The evaluation method is specific to each type of hazard. It leads to the delimitation of a set of areas on the study perimeter constituting a zoning graduated according to the level of the hazard. Award from a hazard level to a given point in the territory takes into account the probability of occurrence of the dangerous phenomenon and its degree of intensity. For multi-random PPRNs, each zone is usually identified on the hazard map by a code for each hazard to which it is exposed. All hazard areas shown on the hazard map are included. Areas protected by protective structures must be represented (possibly specific) because they are always considered to be subject to hazard (case of breakage or inadequacy of the work). Hazard zones may be described as data compiled to the extent that they result from a synthesis using multiple calculated hazard data sources, modelled or observed. These source data are not concerned by this class of objects but by another standard dealing with the knowledge of hazards. Some areas within the study area are considered “no or insignificant hazard zones”. These are the areas where the hazard has been studied and is nil. These areas are not included in the object class and do not have to be represented as hazard zones. However, in the case of natural RPPs, regulatory zoning may classify certain areas not exposed to hazard in a prescribing zone (see definition of Class PPR).本类对象指用于RPP风险分析的灾害分布图（hazard map）上标注的、受一种或多种灾害影响的区域。 灾害分布图（hazard map）是灾害研究的成果，其研究目标为评估研究区域内任意点位的各类灾害强度。评估方法因灾害类型而异，可基于灾害等级对研究范围内的多个区域进行划定并形成分级分区。为区域内指定点位赋予灾害等级时，需综合考量该危险现象的发生概率及其强度等级。 针对多随机PPRNs（multi-random PPRNs），灾害分布图上的每个分区通常会通过对应其所受灾害的编码进行标识。 本类对象涵盖灾害分布图上标注的全部灾害影响区域。受防护结构保护的区域也必须予以标注（可采用专属标识），因为即便有防护结构，这些区域仍可能遭受灾害影响（例如防护结构失效或防护能力不足的情况）。 灾害影响区域可视为经整合后的数据集，其整合来源包括多类经计算、建模或观测得到的灾害数据。本类对象不涉及这些原始数据，相关原始数据需遵循另一项用于灾害认知的标准进行处理。 研究区域内部分区域被划分为“无灾害或灾害可忽略区域”，即经研究确认无灾害影响的区域。此类区域不属于本类对象范畴，无需作为灾害影响区域进行标注。 但针对天然RPPs，监管分区可能会将部分未受灾害影响的区域归类为规定管控区（详见PPR类别（Class PPR）的定义）。