吴忠-灵武地区MS≥5.0地震前波速比变化特征分析  

Analysis on variation characteristics of wave velocity ratio before M_(S)≥5.0 earthquakes in Wuzhong-Lingwu area

作　　者：李文君 曾宪伟[1] 任雪梅[1] 许英才[1] 朱鹏涛[1] 李自芮[1] 马小军[1] LI Wenjun;ZENG Xianwei;REN Xuemei;XU Yingcai;ZHU Pengtao;LI Zirui;MA Xiaojun(Earthquake Agency of Ningxia Hui Autonomous Region,Yinchuan 750001,China)

机构地区：[1]宁夏回族自治区地震局,银川750001

出　　处：《地震地磁观测与研究》2022年第2期1-9,共9页Seismological and Geomagnetic Observation and Research

基　　金：2021年度震情跟踪定向工作任务(项目编号:2021010117);强震危险性研究创新团队项目(项目编号:CX2019-4);宁夏地震科研基金课题(项目编号:NX202013);宁夏自然基金课题(2021AAC03481);宁夏自然科学基金(项目编号:2022AAC03695)。

摘　　要：利用1980年1月—2008年12月宁夏地震台网记录的中小地震事件直达波到时数据,采用单台多震和达法,对吴忠—灵武地区该时段内M_(S)≥5.0地震发生前波速比变化进行回溯性分析,并对该区未来短期内震情趋势进行研判,所得结果表明:①吴忠—灵武地区M_(S)≥5.0地震前波速比存在正常→降低→上升(恢复)→发震的异常变化过程;②研究区台站出现波速比异常,其空间分布对发震位置具有一定指示意义,即发震位置可能位于波速比下降台站或存在异常台站所连线的多边形边缘或内部;③据近期扫描结果,海原地震台波速比异常较显著,需密切关注宁夏南部及邻区地球物理观测资料的变化。Based on the arrival times of direct waves of small and moderate earthquakes recorded by Ningxia Seismic Network,the variation of wave velocity ratio v_(P)/v_(S) before M_(S)≥5.0 earthquakes that occurred in Wuzhong Lingwu area from 1980 to 2008 is retrospectively analyzed,and the earthquake situation in the short-term future is preliminarily discussed.The results show that:①The wave velocity ratio before M_(S)≥5.0 earthquakes in Wuzhong Lingwu area shows the variation of normal→decrease→rise(recovery)→earthquake occurrence,and it is consistent with the conclusions obtained by many domestic researchers;②The spatial distribution of the seismic stations that show wave velocity ratio anomalies has a certain indication significance for the seismogenic position,that is,the seismogenic position may be distributed at the polygonal edge or between the lines of the wave velocity ratio decline or abnormal stations;③According to the recent scanning results,the wave velocity ratio anomaly at Haiyuan Seismic Station(HYU)is significant,so it is necessary to pay close attention to the changes of geophysical data in Southern Ningxia and its adjacent areas.

关 键 词：吴忠—灵武地区 中强震 波速比 

分 类 号：P315.31[天文地球—地震学]