九寨沟M_S 7.0地震前单台波速比变化特征  

Analysis on variation of v_P/v_S at single seismic station before Jiuzhaigou M_S 7.0 earthquake

作　　者：邢康 贾漯昭 程楠[2] 吴亚锋 Xing Kang;Jia Luozhao;Cheng Nan;Wu Yafeng(Henan Earthquake Agency,Zhengzhou 450016,China;Luoyang Seismic Station,Henan Province 471023,China)

机构地区：[1]河南省地震局,中国郑州450016 [2]洛阳地震台,中国河南471023

出　　处：《地震地磁观测与研究》2018年第3期39-44,共6页Seismological and Geomagnetic Observation and Research

基　　金：河南省地震局数字地震学研究创新团队科研项目

摘　　要：收集、整理四川省地震台网2013年5月至2017年9月产出的震相观测报告数据,采用单台多震和达法,重点分析2017年8月8日九寨沟M_S 7.0强震前龙门山断裂带中北段地区波速比变化特征。结果表明:龙门山断裂带中段西侧的茂县地震台,在发震前2年左右,波速比出现一次持续时间约一年半的下降异常;发震前半年左右,波速比出现明显回返特征,波速比回返至均值上下时即发生九寨沟M_S 7.0地震;震源区周边其他6个地震台波速比在发震前变化较平稳。茂县地震台波速比低值异常对判定九寨沟M_S 7.0强震前龙门山断裂带中北段可能存在孕震体具有重要参考价值。Based on the seismic phase data recorded by Sichuan Digital Network from May of 2013 to Septemper of 2017, the variation of wave velocity ratio vP/vS in the middle-northern Longmenshan fault before Jiuzhaigou MS 7.0 earthquake that occurred on Aug.8, 2017 is analyzed by using Wadati method of single station and multi-earthquake. The results show that at MXI station, which is in the western side of middle Longmenshan fault, the velocity ratio decreased for a duration of almost 1.5 years in two years before the earthquake, and it appeared a obvious recovery of vP/vS ratio half a year before the earthquake, which occurred when the vP/vS went up to the mean value, while the ratio did not show abnormal variation at the other six stations. The low wave velocity ratio of MXI before the earthquake may have important reference value for the possible existence of the seismogenic body in the middle-northern Longmenshan fault before Jiuzhaigou earthquake.

关 键 词：九寨沟MS 7.0地震 波速比 单台多震和达法 

分 类 号：P315.31[天文地球—地震学]