概率地震危险性分析、分解与设定地震及其在西安地区的应用

Probabilistic seismic hazard analysis,deaggregation and scenario earthquakes with applications to Xi'an region

本文以Arc GIS为平台,以西安地区为研究对象,以西安地震局提供的信息为依托,给出西安地区的潜在震源区划分以及地震活动性参数,根据随机有限断层模拟得到西安地区地震动强度预测模型,基于离散算法平台,以潜在震源区为基本单位,将潜在震源区离散成栅格并看成点源,分别计算每个栅格对场地的地震动超越概率,即概率地震危险性分析。在此基础上进行概率地震危险性分解去确定某一最可能造成所需危险水平下的地震动强度参数的贡献率,最后根据加权方法确定设定地震。研究结果表明:在0. 2 s、1. 0 s和2. 4 s这3个周期的谱加速度值,相同危险性水平下,对场地贡献较大的潜在震源基本相同,但是各潜在震源的相对贡献率依然有差别;对于不同的危险性水平,对场地贡献较大的潜在震源区的数目区别很大,但基本都是靠近场地附近的几个潜在震源,且比较集中。

Xi'an region was the study objects based on ArcGIS engine platform and the information of the Xi'an seismological bureau,the division of the potential seismic source zones and the seismic activity parameters were adopted,according the stochastic finite fault to obtain the ground motion prediction models,taking the discretization algorithm and choosing potential seismic source zones as the basic unit,dividing the potential seismic source zones into grids which are viewed as point sources and the corresponding exceeding probabilities are calculated,that is probabilistic seismic hazard analysis.On the basis of the deaggregation of probabilistic seismic hazard to define the most dangerous levels corresponding the contribution rate of the ground motion intensity measures,according the weighted method to determine the scenario earthquakes.The results show that,the spectrum of acceleration for the three basic periods at 0.2s,1.0s,and 2.4s,for the same hazard levels,the potential seismic source zones are roughly the same for the site of the larger contribution,but the relative contribution rates have still difference ;For the different hazard levels,the potential seismic source zones are difference for the site of the larger contribution, but several potential seismic source zones are close to the site,and more concentrated.