基于密集台阵的近场与远场地震动迟滞相干函数模型分析  

COHERENCE FUNCTION MODEL ANALYSIS OF NEAR-FIELD AND FAR-FIELD GROUND MOTIONS UPON THE RECORDINGS OF DENSE ARRAY

作　　者：胡进军[1,2] 汤超 HU Jin-jun;TANG Chao(Key Laboratory of Earthquake Engineering and Engineering Vibration,Institute of Engineering Mechanics,China Earthquake Administration,Harbin,Heilongjiang 150080,China;Key Laboratory of Earthquake Disaster Mitigation,Ministry of Emergency Management,Harbin,Heilongjiang 150080,China)

机构地区：[1]中国地震局工程力学研究所,地震工程与工程振动重点实验室,黑龙江哈尔滨150080 [2]地震灾害防治应急管理部重点实验室,黑龙江哈尔滨150080

出　　处：《工程力学》2024年第10期128-141,共14页Engineering Mechanics

基　　金：国家重点研发计划项目(2021YFC3100701,2022YFC3003503);国家自然科学基金项目(U1939210);中国地震局工程力学研究所基本科研业务费专项项目(2021EEEVL0103)。

摘　　要：迟滞相干性是表征地震动空间变化特性的一个重要指标,为研究近场与远场地震动的迟滞相干性的空间变化特性及其差异,基于美国UPSAR台阵记录的2004年Parkfield M_(w)6.0地震的近场记录,以及中国自贡台阵记录的2008年汶川M_(s)8.0地震的远场记录,分别分析了两个密集台阵近场和远场地震动的水平向和竖向相干函数随距离、频率的变化规律,对比了近场和远场地震动迟滞相干性的差异;将基于实际数据的迟滞相干性值与常用的三种相干模型进行拟合分析,揭示了不同相干模型的优势和局限性。结果表明:近场与远场地震动的相干性衰减速度有明显差异,在低频和近距离时,远场记录的相干性要明显大于近场记录;相干性随着距离和频率的衰减速度不同,相干函数模型需要对频率和距离项使用不同的参数描述;现有模型对近场和远场地震动的拟合效果差异较大,对远场记录的拟合效果要优于近场记录;三种模型对同一事件的拟合效果不同,多参数模型效果最好,双参数模型其次,单参数模型适用性较差。研究结果可为近场和远场区相干性模型的选用提供依据。Lagged coherence is an important indicator to characterize the spatial variations of earthquake ground motion.In order to study the spatial variation and their differences of lagged coherence between near-field and far-field ground motion,the analyzed is the horizontal and vertical coherence functions of two dense arrays based on the near-field record of the 2004 Parkfield M_(w)6.0 earthquake recorded by the UPSAR array in the United States and the far-field record of the 2008 Wenchuan M_(s)8.0 earthquake recorded by the Zigong array in China.The horizontal and vertical coherence functions of near-field and far-field ground motion were analyzed separately as a function of distance and frequency,and the differences in lagged coherence were compared.The lagged coherence values based on actual data are fitted and analyzed with three commonly used coherence models to reveal the advantages and limitations of different coherence models.The results show that:there is a significant difference in the decay rate of coherence between near-field and far-field events,and the coherence of far-field recordings is remarkably greater than that of near-field recordings at low frequencies and near distances;coherence decays at different rates with distance and frequency,and the coherence function model requires different parameter descriptions for the frequency and distance terms.The existing models differ in their fits to near-field and far-field ground motion,with better fits to far-field records than to near-field records.The three models fit the same event differently,with the Harichandran model working best,followed by the Feng model,and Luco model being less applicable.

关 键 词：迟滞相干性 近场地震动 远场地震动 密集台阵 功率谱密度 

分 类 号：P315.9[天文地球—地震学]