| 云南剑川近场横波特征及其与构造的关系 |
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| 引用本文： | 雷军,王培德,姚陈,陈运泰.云南剑川近场横波特征及其与构造的关系[J].地球物理学报,1997,40(6):791-801. |
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| 作者姓名： | 雷军 王培德 姚陈 陈运泰 |
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| 作者单位： | 1. 国家地震局地质研究所, 北京 100029;
2. 国家地震局地球物理研究所, 北京 100081 |
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| 摘 要： | 通过对1982年7月3日云南剑川Ms5．4级地震的余震震群近场记录的研究，为该地区存在横波分裂现象及上部地壳存在裂隙各向异性提供了直接的证据．剑川地区地震记录波形复杂，纵、横波视周期差异较大．横波快波偏振主要集中在NE45°和NW55°两个方向．7月20日ML4．8级强余震前后横波快波偏振取向变化显著，各台横波偏振方向震前彼此相对独立；震后整体上趋于有序．前者反映了地震发生前由于震源区应力集中在附近空间形成的应力分布的差异；后者显示出地震发生后由于震源区集中应力的释放带来的上述应力差异在一定空间范围的解除．该结果表明震源附近地区地震横波分裂特征不仅携带着地震处于相对平静期应力场的静态信息，而且也携带着地震发生前后应力场时、空动态变化的重要信息．文中还讨论了剑川地区构造对S波分裂的影响．
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| 关 键 词： | 横波分裂 近场区应力场 云南剑川 |
THE NEAR-FIELD SHEAR WAVE SPLITTING AND ITS RELATION WITH STRUCTURE IN JIANCHUAN, YUNNAN PROVINCE |
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| Lei Jun, Wang Pei-de, Yao Chen, Chen Yun-Tai.THE NEAR-FIELD SHEAR WAVE SPLITTING AND ITS RELATION WITH STRUCTURE IN JIANCHUAN, YUNNAN PROVINCE[J].Chinese Journal of Geophysics,1997,40(6):791-801. |
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| Authors: | Lei Jun Wang Pei-de Yao Chen Chen Yun-Tai |
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| Institution: | 1. Institute of Geology, SSB, Bejing 100029, China;
2. Institute of Geophysics, SSB, Beijing 100081, China |
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| Abstract: | In thes paper, the resultS of a study about the aftershocks swarm of an earthquake of magnitude Mss.4 occurred on July 3, 1982, in Jianchuan, Yunnan province, China, was given and the existences of both shear wave splitting and extensive dilatancy anisotropy in the upper crust of Jianchuan area were recognized. The waveforms recorded in Jianchuan area are more complex. The difference of aPParent period betWeen compressional waves and shear waves is bigger and depends on the conditions of the foundation under each station. The shear wave polarization pattern is different from the unique alignment as reported in the other regions of China, and show tWo dominant directions of NE45°and NW55°. The changes of fast shear wave polarization are very obVious before and after the strong aftershock of magnitude ML 4.8 occond on July 20, 1982, which from a relative independence between stations before the shock to a relative regularization in its entirety after the shock represent that there was an intense local difference of the concentrated stress field before the shock and disaPPeared in a certain extent caused by a stress relief during the shock respectively, and also indicated that some important information concerned with the dynamic change of stress field before and after an earthquake were carried by the splitting shear waves obtained from the area near source. |
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| Keywords: | Shear wave splitting Stress field on the area near source Jianchuan Yunnan |
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