磐安地震序列的震源参数和谱振幅相关系数研究  

Study on Source Parameters and Spectral Amplitude Correlation Coefficients of Pan’an Earthquake Sequence

作　　者：张锦玲[1] 汪贞杰 马小军[1] ZHANG Jinling;WANG Zhenjie;MA Xiaojun(Earthquake Administration of Ningxia Hui Autonomous Region,Ningxia Yinchuan 750001,China;Zhejiang Earthquake Agency,Zhejiang Hangzhou 310013,China)

机构地区：[1]宁夏回族自治区地震局,宁夏银川750001 [2]浙江省地震局,浙江杭州310013

出　　处：《防灾减灾学报》2024年第1期21-28,共8页Journal of Disaster Prevention And Reduction

基　　金：宁夏自然科学基金项目(2022AAC03694)。

摘　　要：基于浙江测震台网记录到的2017年2—9月磐安地区发生的地震序列资料,采用Brune震源模型理论和波谱分析方法,得到磐安震群序列的应力降、视应力等震源参数。利用台站的零频幅值,计算谱振幅相关系数。采用聚类分组,并结合Cut and Paste(CAP)反演方法得到ML4.0主地震事件的震源机制解,系统分析小地震的震源机制的一致性程度。结果显示:震源区应力降值在0.00~0.80 MPa之间,整体构造应力较低;谱振幅相关系数较低,在0.86~0.95之间,震源机制整体相似程度不高;应力积累没有形成一个优势方向,可能指示磐安序列为低摩擦应力的断层作用。研究结果表明:磐安地震序列为普通的小震序列,其震源机制类型与构造应力场基本一致;谱振幅相关分析法可为小震序列的震后快速判定提供重要依据。An earthquake sequence occurred between February and September 2017 in Panan,Zhejiang,China.In this study,the Brune source model and spectral analysis were used to obtain the source parameters(stress drop and apparent stress)from the Zhejiang seismic monitoring network data.Five low-frequency spectral-amplitudes from four nearfield stations were used to calculate the spectral-amplitude correlations.The events were then clustered,and a time series of their moving average correlation was plotted.Focal source mechanisms of the ML 4.0 mainshock were obtained using Cut-and-Paste inversions to analyze focal mechanism similarity for the small and medium earthquakes.The results showed that the Panan earthquake sequence had low spectral-amplitude correlations.The moving average of the correlations varied from 0.86 to 0.95,indicating a low similarity in focal mechanism across the sequence as they became increasingly divergent over time.The overall level of tectonic stress in the seismic source region was low,as the stress drops ranged from 0.00 MPa to 0.80 MPa.As stress accumulation did not show a dominant direction,the Panan earthquake sequence could be attributed to low-friction faulting.The spectral correlation analysis thus shows that the Panan earthquake sequence was an ordinary swarm of small earthquakes.Our approach should be utilized in further analyses,as the resulting data could facilitate rapid post-earthquake sequence assessments.

关 键 词：地震序列 震源参数 应力降 谱振幅相关系数 震源机制 

分 类 号：P315.3[天文地球—地震学]