情景地震震源特征对速度脉冲分布的影响——以虎牙断层为例  

THE INFLUENCE OF SEISMIC SOURCE CHARACTERISTICS ON VELOCITY PULSE DISTRIBUTION IN SCENARIOS:A TEST IN HUYA FAULT

作　　者：纪志伟 李宗超[2] 张琰 琚长辉 JI Zhi-wei;LI Zong-chao;ZHANG Yan;JU Chang-hui(Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)

机构地区：[1]中国地震局地震预测研究所,北京100036 [2]中国地震局地球物理研究所,北京100081

出　　处：《地震地质》2024年第5期1207-1225,共19页Seismology and Geology

基　　金：国家自然科学基金(42104053);国家自然科学基金(41904091);中国地震局地震预测研究所基本科研业务专项(CEAIEF20220209);中国地震局地震预测研究所基本科研业务专项(CEAIEF20240215)。

摘　　要：文中根据中国四川省平武—松潘地区的地质地貌特征和情景地震模型构建流程,建立虎牙断层不同震源特征的情景地震,并采用三维有限差分法进行计算。结合脉冲识别方法研究区域速度脉冲的分布特征,与速度脉冲概率分布曲线进行拟合。结果表明:1)强速度脉冲不仅会出现在断层在地表的投影区域附近,也会由于破裂方向性效应在距震中较远处引发速度脉冲;2)速度脉冲概率分布曲线的形状与模拟得到的速度脉冲分布特征相似,但不同震源机制下的速度脉冲分布存在明显差异,对于不同分量(如EW和NS),拟合效果也存在偏差;3)对于长周期结构,可通过构造措施改变自振周期,从而避开脉冲型地震动的主要周期范围。文中的研究成果能够用于长周期结构的抗震分析,可为虎牙断裂附近区域重大工程的建设和地震危险性分析提供参考。In August 1976,within a week,three earthquakes with a magnitude of 6.5 or higher occurred at the border of Songpan County and Pingwu County in Sichuan Province,China.The seismogenic structure of the three earthquakes is the Huya Fault.The Huya Fault is still a strong active fault,and there is still a possibility of major future earthquakes in the Songpan and Pingwu regions.Historical earthquake records only represent earthquakes that have occurred,and there is uncertainty in estimating earthquake motion using existing records,especially in near-fault areas without strong earthquake records.Estimating near-fault ground motion has become a research hotspot in the interdisciplinary field of seismology and engineering seismology in recent years.The research and methods differ from the design of earthquake motion methods for earthquake safety evaluation in engineering.They are developed by integrating earthquake source physics,seismic wave propagation theory,and engineering seismology.Based on the geological and geomorphological characteristics of the Songpan-Pingwu area in Sichuan Province and the process framework for constructing scenario earthquake models,we have developed three scenario earthquake source models with a magnitude of MW7.0.These models include rupture models and source mechanisms related to the Huya Fault.The seismic source parameters were referenced from existing statistical models.Utilizing the three-dimensional finite difference method,we can simulate the long-term ground motion of scenario earthquakes for its facile discretization and computational efficiency.We set virtual observation stations within the calculated area,enabling the acquisition of velocity wave fields and waveforms across diverse earthquake scenarios.Besides,the velocity pulse identification method is combined to identify the seismic motion of the virtual station to study the distribution characteristics of regional velocity pulses.We use the pulse recognition method to identify velocity pulses of earthquake motion(observed or

关 键 词：情景地震:有限差分法 虎牙断层 速度脉冲 分布概率 

分 类 号：P3159[天文地球—地震学]