中国大陆走滑断层段强震非均匀分布特性及其在工程地震中的应用

An Inhomogeneous Distribution Model of Strong Earthquakes along Strike-Slip Active Fault Segments on the Chinese Continent and Its Implication in Engineering Seismology

通过对中国大陆 5 1条以走滑活动为主的断层段上强震分布的统计分析 ,得出强震沿活动断层段的分布是非均匀的 ,具有趋近段落中心的特点。并建立了强震沿活动断层段的非均匀分布模型 ,其概率分布密度p(K)与K的关系可以表述为p(K) =1 12 0 6e-3 947K2 (K为宏观震中到断层段中心的距离与断层段半长度之比 )。地震危险性分析结果表明 ,相对于均匀模型 ,采用非均匀模型导致了地震危险性分析结果有意义的变化 ,特别是对高震级档年发生率较高的潜在震源区及其附近地区的地震危险性分析结果有明显的影响。该非均匀模型的应用对地震小区划和重大工程场地地震安全性评价有一定的意义。

A statistical analysis was performed to study earthquake distribution along 51 strike-slip active fault segments on the Chinese continent. It is found that strong earthquake distribution along the seismogenic fault segments is inhomogeneous and the distribution probability density p(K) can be stated as p(K)=1.1206e -3.947K2 K=S/(1/2L), S refers to the distance from earthquake epicenter to the center of a fault segment, L is the length of the fault segment. The above-mentioned model can be utilized to modify the probability density of earthquake occurrence of the maximum magnitude interval in a potential earthquake source. It is suitable for the potential earthquake sources delineated along a single seismogenic fault. The utilization of this inhomogeneous model has certain effect on seismic risk analysis,especially for those potential earthquake sources whose earthquake reoccurrence rates of the maximum magnitude interval remain higher. By adopting the inhomogeneous model,the PGA values increase inner the potential earthquake source,but reduce near the vicinity of the potential earthquake source. Taking the Tangyin potential earthquake source as an example,with exceeding probability of 10% and 2% over 50 years, the difference of the PGA values between inhomogeneous model and homogenous models can reach to 12%. As to a potential earthquake source, higher reoccurrence rate of the maximum magnitude interval and lower exceeding probability may cause larger difference of the results of seismic risk analysis.