Study of the Change in Wave Velocity Ratio before and after Two Strong Earthquakes Using Airgun Source Data

作     者：LIU Zifeng YE Beng CHEN Jia ZHOU Qingyun WANG Guangming PENG Guanling LI Yongli 

作者机构：Yunnan Earthquake AgencyKunming 650224China Office of the Western Yunnan Earthquake Prediction Study AreaChina Earthquake AdministrationDali 671000YunnanChina 

出 版 物：《Earthquake Research in China》 (中国地震研究（英文版）)

年 卷 期：2019年第33卷第2期

页      面：305-319页

核心收录：

学科分类：07[理学] 

基　　金：sponsored by the subproject of Relocation of Earthquakes in Yunnan Area under the project of the Major Seismicity Trend in 2019 of Department of Monitoring and Prediction of CEA,the National Natural Science Foundation of China(41474048,41574059) the Science for Earthquake Resilience of China Earthquake Administration(XH18042Y) 

主　　题：Airgun source Wave velocity ratio b-value Focal mechanism consistency 

摘      要：Using the signals excited by the large-volume airgun source at the Binchuan transmitting seismic station from January to June,2016,arrival-time data was acquired at four stations near the epicenter of the Eryuan MS4.5 and MS4.0 earthquakes on February 8,2016,as well as the epicenter of the Yunlong MS5.0 and Eryuan MS4.6 earthquakes on May 18,2016 through the waveform cross-correlation *** wave velocity ratio of the four stations was calculated using the single-station *** the same time,the b-value and the focal mechanism consistency parameters of the study area were also *** results show that:(1)the wave velocity ratio of each station experienced a process of decline-recovery-fast rise before the two strong earthquakes,and a significant quasi-synchronous rapid rise occurred within 3-12 days before the earthquake;(2)the timing of the rapid rise of the wave velocity ratio of the four stations before the Yunlong MS5.0 and Eryuan MS4.6 earthquakes were related to the epicentral *** station which observed the earliest increase in rapid rise is the farthest one from the epicenter,and the station where the rapid rise appeared in the latest is closest to the epicenter;(3)the form of change of the wave velocity ratio before the earthquake was different between stations located at different directions in the epicenter area;(4)the b-value and the focal mechanism consistency parameter which is commonly used to characterize the stress level both showed a downward trend before the two strong earthquakes,and were consistent with the change in the wave velocity *** to the preliminary analysis,the wave velocity ratio obtained by using airgun source can better reflect the change in the stress state of the underground medium.