震源深度范围内视电阻率随时间变化的观测试验及其与地震活动的关系
OBSERVATION OF CHANGES WITH TIME OF APPARENT RESISTIVITY WITHIN THE DEPTHS OF EARTHQUAKE FOCI AND THE OCCURRENCE OF EARTHQUAKES
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摘要: 本文讨论了青海祁连俄博测点和甘肃山丹霍城测点1979年7月——1986年10月间的大地电磁测深重复观测试验结果。测点所在地区的电磁干扰背景较小、地震活动性较强。文中分析了观测记录和资料处理中的误差。结果表明,以初始值为基准,俄博测点1984年两次复测的视电阻率曲线在部分频带范围内出现过15——30%左右的系统变化,与此期间测区附近发生的一些M5的地震活动有着一定的对应关系;1985年复测的视电阻率曲线又恢复至初始值,而此期间测区附近没有M5及其以上的地震活动,1986年霍城测点和俄博测点复测的视电阻率曲线在较宽的频带范围内发生了40——70%左右的系统变化,与此期间震中距为60km左右的青海门源M=6.7,5.7和5.0地震群密切相关。Abstract: This paper deals with test results of repeated observations of the apparent resistivity at the Ebo site,Qilian,Qinghai Province and at Huocheng,Shandan,Gansu Province from July 1979 to October 1986 by the MT method. The noise background is low and seismicity is high around the observation sites. The errors of observations are analysed and discussed. It is found that in comparison with initial curves,systematic changes of 15-30% in the apparent resistivity in part of the frequency range of two repeated observations in 1984 at the Ebo site were associated with the occurrences of earthquakes of M5 around the sites; then returning to initial values when measurements were repeated in 1985 at the Ebo site with no earthquakes of M5 occurring around the sites. Systematic changes of 40-70% in the apparent resistivity in the entire frequency range repeatedly observed in 1986 at the Ebo site and at the Huocheng site were closely associated with the occurrences of earthquakes of M=6.7,5.7,5.0 at Menyuan,Qinghai Province. The epicentral distances of the two observation sites were about 60 km.
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[1] 国家地展局兰州地震研究所大地电磁测深组,1987.河西走廊及其附近地区的大地电磁测深.勘探地球物理专辑第二辑,大地电磁测深,138——144,地质出版社.
[2] 张云琳、郭守年、司玉兰,1987.我国西北部分地区大地电磁观测中的信噪比.勘探地球物理专辑第二辑,大地电磁测深,105——114地质出版社.
[3] 张云琳、司玉兰、郭守年、安海静,1987.用大地电磁测深法来监测地壳电性随时间变化的初步研究.西北地震学报,1: 54——61,
[4] 刘国栋、毛桐恩,1984.大地电磁测深法在地震研究中的应用.大地电磁侧深研究,348——359地震出版社.
[5] 马宗晋、张德成,1986.板块构造与地震.板块构造基本问题,363——391,地震出版社.
[6] 罗灼礼,1979.印度洋板块向北顶撞与我国西部及邻区现代构造应力场和地震活动的关系.西北地震学报,4.11——21
[7] 赵玉林、钱复业,1978,唐山7.8级强震前震中周围形变电阻率的下降异常.地球物理学报,21 181——190
[8] Qian Jadong, Gui Xitai, Ma Huaizhou, Ma Xikang, Guan Huaping and Zhao Qingming, 1979,
[9] Observations of apparent resistivity in the shallow crust before and after several great shallow earthquake, Procedings of the International Symposium on Earthquake Prediction,145——155,Paris, UNESCO.[1] 国家地展局兰州地震研究所大地电磁测深组,1987.河西走廊及其附近地区的大地电磁测深.勘探地球物理专辑第二辑,大地电磁测深,138——144,地质出版社.
[2] 张云琳、郭守年、司玉兰,1987.我国西北部分地区大地电磁观测中的信噪比.勘探地球物理专辑第二辑,大地电磁测深,105——114地质出版社.
[3] 张云琳、司玉兰、郭守年、安海静,1987.用大地电磁测深法来监测地壳电性随时间变化的初步研究.西北地震学报,1: 54——61,
[4] 刘国栋、毛桐恩,1984.大地电磁测深法在地震研究中的应用.大地电磁侧深研究,348——359地震出版社.
[5] 马宗晋、张德成,1986.板块构造与地震.板块构造基本问题,363——391,地震出版社.
[6] 罗灼礼,1979.印度洋板块向北顶撞与我国西部及邻区现代构造应力场和地震活动的关系.西北地震学报,4.11——21
[7] 赵玉林、钱复业,1978,唐山7.8级强震前震中周围形变电阻率的下降异常.地球物理学报,21 181——190
[8] Qian Jadong, Gui Xitai, Ma Huaizhou, Ma Xikang, Guan Huaping and Zhao Qingming, 1979,
[9] Observations of apparent resistivity in the shallow crust before and after several great shallow earthquake, Procedings of the International Symposium on Earthquake Prediction,145——155,Paris, UNESCO.
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