李冬梅
山东省地震局, 济南 250102
基金项目: 中国地震局星火计划（XH18026Y，XH16025Y），山东省自然基金（ZR2017QD014），山东省科技发展计划项目（2014GSF120007）与山东省地震局十二五重点项目（SD1250501）联合资助
详细信息
作者简介: 郑建常, 男, 1978年生, 研究员, 2011年于中国地震局地球物理研究所获博士学位, 主要从事地震活动性及数字地震学研究.E-mail:zjcmail@yeah.net
中图分类号: P315 收稿日期:2018-04-03
修回日期:2019-01-17
上线日期:2019-05-05
Inversion for velocity ratios in focal areas based on error distribution and its application: A study on variations of medium properties in the source of the Rushan earthquake swarm
ZHENG JianChang,LI DongMei
Shandong Earthquake Agency, CEA, Jinan 250102, China
MSC: P315
--> Received Date: 03 April 2018
Revised Date: 17 January 2019
Available Online: 05 May 2019
摘要
摘要:本文利用误差分布和概率统计分析改进了波速比计算方法.对于震源位置相对集中的震群活动，对台站震相到时进行两次差分，通过对差分后的震相数据对进行二维高斯分布拟合，可以稳健地估计震群活动震源区波速比.该方法充分利用了不同台站Pg、Sg到时差的所有信息，其优势是不需要地震事件的震源位置，并且不依赖震源区以外的速度变化，有效消除了震源区到台站的传播路径效应的影响；相对于传统的平均波速比，本文方法得到的震源区波速比，更能真实地反映震源区介质的性质.我们将该方法应用到2013-2016年的乳山震群，结果显示：震源区波速比的变化与震群活动过程密切相关，波速比的变化反映了序列活动的阶段性特征.
关键词: 双差波速比/
误差分析/
二维高斯分布/
乳山震群
Abstract:We improve the velocity ratio estimating method for compact earthquake clusters by using error distribution and probability statistical analysis. Similar to double difference technique in relative earthquake location, we also use differential P and S phase times of each pair of events. Furthermore, the multivariate Gaussian distribution fitting method is adopted to estimate VP/VS ratios robustly in source areas. Our method takes full information from Pg and Sg times over all stations. Its advantages are that precise focal positions are not needed, and it no longer relies on velocity information outside the source area. The ray-path effect is remarkably eliminated in this method. Comparing with the traditional average velocity ratio, the velocity ratio obtained by our method can reflect better properties of media in the source area. This method is applied to the Rushan earthquake swarm which occurred from 2013 to 2016. Results show that variations of VP/VS ratio in the source area are closely related to seismic activities and reflect some stage characteristics of the swarm.
Key words:Velocity ratio/
Error analysis/
Multivariate Gaussian distribution/
Rushan earthquake swarm
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http://www.geophy.cn/data/article/export-pdf?id=dqwlxb_14971
