| 2008年汶川MS8.0地震前定点观测电磁异常回溯性分析 |
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| 引用本文： | 解滔,刘杰,卢军,李美,姚丽,王亚丽,于晨.2008年汶川MS8.0地震前定点观测电磁异常回溯性分析[J].地球物理学报,2018,61(5):1922-1937. |
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| 作者姓名： | 解滔 刘杰 卢军 李美 姚丽 王亚丽 于晨 |
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| 作者单位： | 中国地震台网中心, 北京 100045 |
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| 基金项目： | 中国地震局震情跟踪课题（2018010402）和国家自然科学基金项目（41774084）联合资助. |
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| 摘 要： | 对2008年汶川MS8.0地震周围定点台站观测的电磁异常的相关研究进行了简要的回顾分析，以期加深对汶川地震孕震过程中电磁异常的解读.震中周围8个地电阻率台站震前出现不同形态的异常变化，结合震后地电阻率变化形态分析，仅近邻地震破裂带的成都和江油台异常变化符合已有的地电阻率孕震异常机理.在4月24日和5月9日大致沿南北地震带出现两条南北走向的低点位移线，成都台地磁转换函数、谐波振幅比、帕金森矢量和垂直极化强度等主要反映了地下介质电性在震前出现的异常变化；断裂带附近的地电场和电磁扰动在震前出现波形畸变和能量增强，距离较远的西昌台阵和天祝—松山台阵内地电场也出现功率谱能量增加和裂隙渗透方位角扰动等短期异常现象，甚至沿龙门山断裂带NE方向1300km外的河北电磁扰动台网震前数月也出现自观测以来最大幅度的异常变化.
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| 关 键 词： | 汶川地震 电磁数据 定点台站 地面观测 异常变化 |
| 收稿时间： | 2018-03-12 |
Retrospective analysis on electromagnetic anomalies observed by ground fixed station before the 2008 Wenchuan MS8.0 earthquake |
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| XIE Tao,LIU Jie,LU Jun,LI Mei,YAO Li,WANG YaLi,YU Chen.Retrospective analysis on electromagnetic anomalies observed by ground fixed station before the 2008 Wenchuan MS8.0 earthquake[J].Chinese Journal of Geophysics,2018,61(5):1922-1937. |
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| Authors: | XIE Tao LIU Jie LU Jun LI Mei YAO Li WANG YaLi YU Chen |
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| Institution: | China Earthquake Networks Center, CEA, Beijing 100045, China |
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| Abstract: | This paper tries to take a retrospective analysis on the electromagnetic anomalies recorded by fixed stations prior to the 2008 Wenchuan MS8.0 earthquake, and to further understanding these anomalies during the seismogenic process. There were 8 georesistivity stations around the epicenter exhibiting different types of abnormal changes before the main shock. Combining analysis on the successive data after the shock, only the anomalies of Chengdu and Jiangyou stations, which are located near the rupture zone, can be explained by the existing geo-resistivity anomaly mechanism companying the seismogenic process. Two north-south geomagnetic vertical component minimum point shift lines appeared on April 24 and May 9, 2008, respectively, which are distributed approximately along the north-south seismic belt where the Wenchuan earthquake occurred. Some parameters extracted from geomagnetic data of the Chengdu station showed abnormal variations, including the transfer function, harmonic amplitude ratio, Parkinson vector, and vertical polarization intensity, which mainly reflect the underground conductivities. The geoelectric field and electromagnetic data near the rupture zone displayed phenomena of waveform distortion and energy enhancement. The geoelectric field recorded at the Xichang geoelectric monitoring array and Tianzhu-Songshan monitoring array also showed phenomena of power spectrum energy increases and disturbances of the fracture water penetration direction calculated from the geoelectric field data. Three stations in the Hebei electromagnetic monitor network, which was more than 1300km far from the epicenter in NE direction to the Longmen Shan fault, recorded the most obvious abnormal variations a few months before the earthquake since the 1980s. |
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| Keywords: | Wenchuan earthquake Electromagnetic data Fixed station Ground monitoring Anomalous variations |
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