2013年岷县—漳县6.6级地震地磁垂直分量日变化低点时间空间分布特征
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摘要
2013年6月16日,中国大陆西部出现地磁低点位移。异常出现后一个月内,位于低点位移分界线附近发生7月22日岷县、漳县交界6.6级地震。本文通过采用实测低点时间减去理论低点时间的方法剔除低点时间经度效应,并以剔除经度效应后低点时间为0 h的等值线作为低点位移分界线, 2013年岷县—漳县6.6级地震震中处于6月16日地磁低点位移分界线上。对异常期间的中国大陆地区地磁垂直分量日变形态进行统计,发现其存在显著的分区特征,低点时间为正的区域内日变化形态基本呈现W型,低点时间为负的区域内日变化形态主要呈现V字型特征。低点位移异常日期间,中国大陆存在显著的高梯度带,本文采用梯度值定量描述低点时间空间变化程度。在6月13日正常日期间,中国大陆地区未出现梯度值大于1.5 h/(°)的区域,在6月16日异常日期间,出现梯度值大于1.5 h/(°)的区域, 2013年岷县—漳县6.6级地震位于高梯度区边缘。
The geomagnetic low-point displacement appeared on June 16 th, 2013. In this paper, low-point time longitude effect is eliminated by the method of subtracting theoretical low-point time from measured low-point time. The isoline with low-point time of 0 h after eliminating the longitude effect is used as the boundary of low-point displacement. The epicenter of the M6.6 Minxian—Zhangxian earthquake is at the boundary of the geomagnetic low point displacement on June 16 th. The diurnal variation of geomagnetic vertical components in mainland China during abnormal periods is statistically analyzed. There are significant zoning features. The diurnal variation pattern in the area with positive low-point time presents W type, while the diurnal variation pattern in the area with negative low-point time mainly presents V type characteristics. During the abnormal period, there are significant high gradient zones in the mainland of China. In this paper, the gradient value is used to quantitatively describe the spatial and temporal variation of low-point time. During the normal period of June 13 th, there is no region in the mainland of China with a gradient value greater than 1.5 h/(°). During the abnormal period of June 16 th, there is area with a gradient value greater than 1.5 h/(°). The epicenter of the 2013 M6.6 Minxian—Zhangxian Earthquake is located at the edge of the high gradient region.
The geomagnetic low-point displacement appeared on June 16 th, 2013. In this paper, low-point time longitude effect is eliminated by the method of subtracting theoretical low-point time from measured low-point time. The isoline with low-point time of 0 h after eliminating the longitude effect is used as the boundary of low-point displacement. The epicenter of the M6.6 Minxian—Zhangxian earthquake is at the boundary of the geomagnetic low point displacement on June 16 th. The diurnal variation of geomagnetic vertical components in mainland China during abnormal periods is statistically analyzed. There are significant zoning features. The diurnal variation pattern in the area with positive low-point time presents W type, while the diurnal variation pattern in the area with negative low-point time mainly presents V type characteristics. During the abnormal period, there are significant high gradient zones in the mainland of China. In this paper, the gradient value is used to quantitatively describe the spatial and temporal variation of low-point time. During the normal period of June 13 th, there is no region in the mainland of China with a gradient value greater than 1.5 h/(°). During the abnormal period of June 16 th, there is area with a gradient value greater than 1.5 h/(°). The epicenter of the 2013 M6.6 Minxian—Zhangxian Earthquake is located at the edge of the high gradient region.
引文
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[18] 戴苗,李军辉,刘坚,等.安庆地震前地磁异常特征[J].地质科技情报,2014,33(6):187-191.
[19] 刘长生,段莉莉.东北地区中强地震与地磁总场强度异常变化关系研究[J].防灾减灾学报,2015,31(4):43-48.
[2] 丁鉴海.地磁日变地震预报方法及其震例研究[M].北京:地震出版社,2009.
[3] 丁鉴海.地震地磁学[M].北京:地震出版社,1994.
[4] 陈绍明.地磁日变低点位移分界线的网络分布及其与地震关系的探讨[J].地震,1987,10(5):33-39.
[5] 冯志生,李琪,李鸿宇,等.地磁低点位移线两侧异常变化的反相位现象及其解释[J].中国地震,2009,25(2):206-213.
[6] 何文贵,郑文俊,王爱国,等.临潭-宕昌断裂新活动特征与岷县漳县MS6.6地震关系研究[J].地震工程学报,2013,35(4):751-760.
[7] 冯红武,张元生,刘旭宙,等.2013年甘肃岷县漳县MS6.6地震及其余震序列重定位[J].地震工程学报,2013,35(3):443-447.
[8] 杨彦明,张国清,陈婧,等.鄂尔多斯块体北缘及邻区Moho面深度特征[J].地震地磁观测与研究,2016,37(6):1-8.
[9] 杨彦明,姜立新,王祯祥.基于Levenberg-Marquardt方法的内蒙古及邻区地震烈度影响场改进技术[J].地震,2017,37(3):117-126.
[10] 吴长祥,刘苗,吴健生.克里格方法在大地电磁静校正中的应用[J].石油物探,2008,47(1):89-94.
[11] 高彦伟,戴经隆,马瑞杰.时空域克里格方法在地下水水质评价中的应用[J].工程勘察,2007,(10):38-41.
[12] 赵凯华,陈熙谋.电磁学.上册[M].北京:高等教育出版社,1978.
[13] 袁桂平,张学民,吴迎燕,等.汶川8.0级地震前地磁低点位移与内外源S_q等效电流体系关系的研究[J].地震,2015,35(3):102-112.
[14] 冯志生,林云芳,王建宇,等.江苏地磁加卸载响应比的异常标志体系[J].地震,2000,20(2):61-68.
[15] 戴勇,高立新,杨彦明,等.甘—青地区地磁垂直分量加卸载响应比、 逐日比分析[J].华南地震,2015,35(3):1-6.
[16] 李鸿宇,朱培育,王维,等.2013年前郭5.8级震群的地磁多方法异常分析[J].地震研究,2018,41(1):111-117.
[17] 倪晓寅,陈莹.福建地磁谐波振幅比异常与台湾强震的关系研究[J].华南地震,2016,36(3):56-60.
[18] 戴苗,李军辉,刘坚,等.安庆地震前地磁异常特征[J].地质科技情报,2014,33(6):187-191.
[19] 刘长生,段莉莉.东北地区中强地震与地磁总场强度异常变化关系研究[J].防灾减灾学报,2015,31(4):43-48.