| 极化法在提取震磁异常信息方面的应用 |
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| 引用本文： | 张敏,赵石柱,贾路,刘立霞,滕云田.极化法在提取震磁异常信息方面的应用[J].地球物理学进展,2020(2):488-494. |
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| 作者姓名： | 张敏 赵石柱 贾路 刘立霞 滕云田 |
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| 作者单位： | 中国地震局地球物理研究所;新疆维吾尔自治区地震局 |
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| 基金项目： | 新疆地震科学基金“基于Matlab软件的数学算法对新疆区域地磁观测资料干扰分析及去噪处理”(201814);“呼图壁储气库注采过程的区域应变过程研究”(201715);国家重大科研设备研制项目(2014YQ10081704)联合资助. |
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| 摘 要： | 本文利用极化方法,提取和分析新疆区域2008-2017年拥有秒采样数据的乌鲁木齐、喀什、且末、温泉4个台站的垂直幅度极化值,分析极化值异常与新疆及其邻区2008年以来6级以上地震的关系.地磁场观测较容易受到高空电流体系等外源场的影响,为了分析外源场对极化值的影响,统计了2008-2017年共计64次磁暴期间的极化值,4个台站磁暴期间极化值都非常小,除了温泉台有1次大于2倍均方差之外,其余全部都小于各个台站的2倍均方差(极化值异常初始阈值为3倍均方差),同时通过计算出的极化值与K_p指数的相关系数可以看出,4个台站的相关系数都非常小(小于0.2),基本可以判断极化值在磁场扰动时应该表现为低值,而大量研究表明地震之前极化值会出现高值异常,因此基本排除了外源场对极化值的影响.2008-2017年共计93次5级以上地震,因各个台站背景噪声和仪器噪声以及构造背景差别较大,计算出的极化值幅度差别较大,各个台站极化值之间不具有可比性.结果表明:当各个台站的震中距相当时,震级越大,异常幅度越大.喀什台由于与多国交界,地质构造环境更为复杂,异常幅度等显示出更为复杂的特性,因此漏报等情况也较多.
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| 关 键 词： | 极化法 地磁秒数据 短临异常 |
Applying of polarization method to extract short term seismic anomaly from geomagnetic second data |
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| ZHANG Min,ZHAO Shi-zhu,JIA Lu,LIU Li-xia,TENG Yun-tian.Applying of polarization method to extract short term seismic anomaly from geomagnetic second data[J].Progress in Geophysics,2020(2):488-494. |
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| Authors: | ZHANG Min ZHAO Shi-zhu JIA Lu LIU Li-xia TENG Yun-tian |
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| Institution: | (Institute of Geophysics,Earthquake Administration of China,Beijing 100081,China;Earthquake Agency of Xinjiang Uygur Autonomous Region,Urumqi 830011,China) |
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| Abstract: | Applied of polarization analysis in this paper, used data from January 1, 2008 to October 31, 2017, about 9 years data to extract the vertical component polarization value, the possible seism-electromagnetic phenomena before earthquake bigger than 5 were analyzed. In 2008-2017, the polarization values during the 64 magnetic storms were calculated. The four stations had very small polarization value, all of which were less than two times mean variance of each station(the initial threshold of the anomaly of the polarization is three times mean variance) except for Wenquan station at one storm. The correlation coefficient between polarization value and K_p index were calculated at the four stations, and the values were very small(less than 0.2). So it is basically possible to judge that the polarization value should show a low value when the magnetic field was disturbed, but many research showed that the polarization value would have a high value before large earthquake, so the influence of external source field on the polarization value is basically excluded. We totally considered 93 earthquakes with magnitude above 5 from 2008 to 2017 in this paper, calculated the polarization value of the four stations in this period. We could see from the result that: due to the great differences in background noise, instrument noise and tectonic background of each station, the calculated polarization values were greatly different and could not be comparable. But when the epicenter distance of each station were equal, the larger the magnitude, the larger the abnormal amplitude. Kashi was adjacent to many countries, had a more complex geological and structural environment, so the abnormal amplitude showed a much more complex features, and had many lost anomaly value before earthquakes. |
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| Keywords: | Polarization method Geomagnetic second data Short term anomaly |
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