Abstract: Diffuse earthquake refers to the maximum earthquake potential not associated with the identified seismogenic structures. The assessment of diffuse earthquake is a key point in nuclear power plant siting. As one part of the regional seismotectonic model,the diffuse earthquake plays an important role in SL-2 determination,because nuclear power plant is usually sited in the region of lower seismicity. Diffuse earthquake usually consists of moderate or small earthquakes of magnitudes less than 6,and the evaluation of diffuse earthquake is carried out in the seismotectonic province. The concept of“seismotectonic province”has been used to represent diffuse seismicity for the purpose of seismic hazard assessment,with each seismotectonic province assumed to encompass an area of equal seismic potential,that is to say the“diffuse earthquake”. The principles and methods of delineating seismotectonic province are discussed in detail in this paper. According to the related nuclear safety statutes,it is necessary to make reasonable assessment of diffuse earthquake for each seismotectonic province,especially for area where the nuclear power plant is sited. After discussing the principles for diffuse earthquake assessment,the paper puts forward the methods for evaluating the magnitude of diffuse earthquake based on the concept of diffuse earthquake by using seismic and geological data. The paper has also discussed how to determine the specific distance of the diffuse earthquake to the site in the seismotectonic province where the nuclear power plant is located.

Key words: assessment of diffuse earthquake, seismotectonic province, nuclear power plant siting

摘要： 弥散地震评价是核工程选址中地震安全性评价的重要内容之一。文中在分析弥散地震涵义的基础上,论述了弥散地震评价中地震构造区划分的原则和依据、弥散地震确定的方法和技术途径等关键性技术内容。

关键词: 核工程选址, 弥散地震, 地震安全性评价