地震巨灾模型中的随机地震事件集模拟

Simulation of Stochastic Seismic Event Set Using the Earthquake Catastrophe Model

地震巨灾保险是降低地震灾害风险的有效手段之一,而地震危险性分析是地震巨灾模型的主要分析模块之一。传统的概率地震危险性分析主要是基于潜在震源模型、地震活动性模型和地震动衰减模型等并采用概率方法得到场点的地震危险性值,该危险性表示的是未来所有地震对场点的综合影响。然而,在使用地震巨灾模型进行地震风险分析时需要用到单个地震事件对场点的影响,这就需要根据潜在震源区生成一系列单个地震事件,并计算每个事件对场点的影响。本研究采用蒙特卡洛方法,基于第五代中国地震动参数区划图中所采用的地震活动性模型(潜在震源区及其地震活动性参数),模拟符合我国地震活动时间、空间和强度分布特征的地震事件集。模拟时遵从的基本理论为:地震发生在时间上符合泊松分布,震级分布可用古登堡-里克特定律来描述,空间分布特征则用潜在震源区及其地震发生率来描述。模拟得到的地震事件包含以下参数:时间(年、月、日)、地点(经度、纬度)、深度、震级、断层走向以及衰减特征等。该模拟地震事件集可满足地震巨灾模型中地震风险分析的需求,已应用于我国地震巨灾模型中。

Earthquakes are a type of major natural disaster that result in serious casualties and property losses.Seismic hazard analysis is one of the main modules in the seismic catastrophe model.Traditional probabilistic analyses of seismic hazard are based on the potential source model,seismicity model,and ground motion attenuation model,which use the probability method to determine the seismic hazard of the target site.This hazard represents the combined effect of all earthquakes on the site.However,the effect of a single seismic event on the site should be used in seismic risk analyses based on the earthquake catastrophe model,so the potential focal area must be converted into a series of individual seismic events.In this study,based on the potential focal area and seismicity model adopted in the fifth seismic ground motion parameters of China’s zonation map,we used the Monte Carlo method to simulate the seismic event set that conforms to the time,space,and intensity distribution characteristics of seismic activity in China.In the simulation of seismic events,the basic theory states that the occurrence time of earthquakes follows a Poisson distribution,the magnitude distribution is described by the Gutenberg-Richard law,and the spatial distribution is described by the potential focal area and the earthquake occurrence rate.The simulated earthquake events included the following parameters:time(year,month,and day),location(longitude,latitude),depth,magnitude,fault strike,and attenuation characteristics.The results show that this simulated seismic event set can meet the requirements of seismic hazard analysis in the seismic catastrophe model.