| 2019年四川长宁MS6.0地震序列S波分裂变化特征 |
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| 引用本文： | 黄春梅,吴朋,李大虎,王宇航,林向东.2019年四川长宁MS6.0地震序列S波分裂变化特征[J].地震学报,2021,43(3):303-320. |
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| 作者姓名： | 黄春梅 吴朋 李大虎 王宇航 林向东 |
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| 作者单位： | 中国成都 610041 四川省地震局;中国北京 100080 北京市地震局 |
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| 基金项目： | 中国地震局地震科技星火计划项目（XH20001，XH20051）、国家重点研发计划（2018YFC1504501-02）、国家自然科学基金（41974066）、四川省地震局紧急地震信息服务创新团队（201801）和四川省科技应用基础研究项目（2020YJ0474）共同资助 |
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| 摘 要： | 本文采用质点运动判别与偏振分析相结合的方法对2019年四川长宁MS6.0地震震源区10个台站于2013年4月25日至2019年7月31日记录到的波形数据进行S波分裂参数测定,其中9个台站获取4条以上有效S波分裂参数.结果表明,震源区各台站的S波分裂参数不仅在空间上存在分区特征,还会随时间发生改变.快波偏振方向在空间上的...
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| 关 键 词： | 2019年长宁MS6.0地震 S波分裂 快波偏振方向 慢波时间延迟 地壳各向异性 |
| 收稿时间： | 2020-07-22 |
Variation characteristic of S-wave splitting on the 2019 Changning MS6.0 earthquake sequence,Sichuan |
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| Huang Chunmei,Wu Peng,Li Dahu,Wang Yuhang,Lin Xiangdong.Variation characteristic of S-wave splitting on the 2019 Changning MS6.0 earthquake sequence,Sichuan[J].Acta Seismologica Sinica,2021,43(3):303-320. |
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| Authors: | Huang Chunmei Wu Peng Li Dahu Wang Yuhang Lin Xiangdong |
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| Institution: | 1.Sichuan Earthquake Agency，Chengdu 610041，China2.Beijing Earthquake Agency，Beijing 100080，China |
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| Abstract: | In this paper, the S-wave splitting parameters of the waveform data recorded at 10 stations in the source area of the 2019 Changning MS6.0 earthquake, Sichuan, from April 25, 2013 to July 31, 2019 were measured by the particle motion discriminant method combined with the polarization analysis method. More than four effective S-wave splitting parameters are obtained at nine stations. The results show that the S-wave splitting parameters at the stations in the studied region are characterized by partition in space and variation over time. The characteristics of fast wave polarization direction in space are as follows: the predominant polarization direction of fast S-wave at three stations in the southeastern source area of the Changning earthquake is in the direction of NE, which is consistent with direction of regional principal compressive stress in the southeastern source area. In the northwestern source area, the predominant polarization directions of fast S-wave, nearly EW, is consistent with the directions of regional principal compressive stress in the northwestern source area. Due to the combining effect of crustal stress and complex fault structure, the three stations CJW, GXA and LQS all have two predominant polarization directions of fast S-wave. The polarization directions of fast S-wave change with time as follows: After the main shock, the polarization directions of fast S-wave at each station gradually tended to be convergence after the dispersion increases; the polarization directions of fast S-waves at the station CJW changed three months before the main shock, indicating that with the accumulation of the stress during the seismogenic process, the anisotropic characteristics at the station CJW are controlled mainly by stress instead of structure. As for the temporal distribution, the average normalized delay time of slow S-wave at each station decreased as the distance increasing from the main shock and aftershock dense area to stations, reflecting the stronger accumulation and releasing of stress during seismogenic process in the aftershock dense area. In addition, the normalized delay time of slow S-wave at the station CNI decreased significantly about six months before the main shock, and increased rapidly after the main shock, suggesting the accumulation of stress before the earthquake and the abrupt release of stress after the earthquake lead to the change in geometry of the micro-cracks in upper crust. |
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