地震研究

利用2013年3月3日洱源5.5级地震前后所获得的2种流动地磁资料,分析了地磁总强度与矢量观测的异常变化特征。(1)地磁总强度观测结果表明:地震前,测区内相邻期总强度变化的正负值区大致均衡,逐渐演变为整个测区都是正值并出现高梯度带,正值的高梯度带再演变为正负值交界的高梯度带,此时震中位于正值高梯度带的边缘; 地震后,正负值交界的高梯度带远离震中,正负值区又大致均衡;(2)地磁矢量观测结果表明:地震前,岩石圈磁场变化的水平矢量、垂直矢量在震区均有显著差异,磁偏角、磁倾角和总强度变化的零等变线均在震区周边穿过; 地震后,岩石圈磁场变化的水平、垂直矢量在震区的显著差异消失,磁偏角和总强度在震区正负值交界的高梯度带逐渐消失,磁偏角的零等变线在震区未出现。

In this paper,the author uses two kinds of mobile geomagnetic data before and after Eryuan M5.5 earthquake on Mar. 3,2013,to analyze the characteristics of anomalous change in total geomagnetic intensity and geomagnetic vectors.(1)The observation results of total geomagnetic intensity show that before the Eryuan M5.5 earthquake,in the surveying area,for the successive surveying periods,the positive zones were approximately equal to the negative ones. Then,the whole surveying area gradually evolved into the positive one,and the high gradient belt appeared,which evolved into the high-gradient zone containing positive and negative values. The epicenter of the Eryuan M5.5 earthquake was located at the edge of positive high-gradient zone. After the earthquake occurred,the high gradient belt containing the positive and negative values was located far from the epicenter,and the positive and negative areas became balanced again.(2)The observed geomagnetic vector show that before the Eryuan M5.5 earthquake,the horizontal and vertical vectors of lithosphere magnetic field had significant variations in earthquake area. The zero lines of the declination,inclination and total intensity all crossed near the earthquake area. After the earthquake occurred,in the earthquake area,the significant variations of these vectors disappeared,and the high-gradient zone containing the positive and negative values gradually disappeared. The inclination and total intensity also disappeared,and the zero line of the declination did not appear in the earthquake area.

引言
1 地磁资料与计算方法
2 地磁总强度的变化
3 地磁矢量的变化
4 结论与讨论

图1 滇西地震预报实验场地磁总强度测点分布<br/>Fig.1 Distribution of measuring points of geomagnetic total intensity in Western Yunnan Earthquake Prediction Study Area

图1 滇西地震预报实验场地磁总强度测点分布
Fig.1 Distribution of measuring points of geomagnetic total intensity in Western Yunnan Earthquake Prediction Study Area

图2 云南及周边地区地磁矢量测点分布<br/>Fig.2 Distribution of measuring points of geomagnetic vector in Yunnan and its adjacent region

图2 云南及周边地区地磁矢量测点分布
Fig.2 Distribution of measuring points of geomagnetic vector in Yunnan and its adjacent region

图3 2011年2月～2014年2月滇西地震预报实验场相邻期总强度变化分布图<br/>(a)2011-02～2011-09;(b)2011-09～2012-02;(c)2012-02～2012-09;(d)2012-09～2013-02; <br/>(e)2013-02～2013-09;(f)2013-09～2014-02<br/>Fig.3 Distribution of geomagnetic total intensity in successive period in Western Yunnan Earthquake Prediction Study Area from Feb., 2011 to Feb., 2014

图3 2011年2月～2014年2月滇西地震预报实验场相邻期总强度变化分布图
(a)2011-02～2011-09;(b)2011-09～2012-02;(c)2012-02～2012-09;(d)2012-09～2013-02;
(e)2013-02～2013-09;(f)2013-09～2014-02
Fig.3 Distribution of geomagnetic total intensity in successive period in Western Yunnan Earthquake Prediction Study Area from Feb., 2011 to Feb., 2014

图4 2011～2012年云南及周边地区岩石圈磁场变化分布图<br/>(a)水平矢量;(b)垂直矢量;(c)磁偏角;(d)磁倾角;(e)总强度<br/>Fig.4 The lithosphere magnetic change distribution in Yunnan and its adjacent regions from 2011 to 2012(a)horizontal vector;(b)vertical vector;(c)magnetic declination;

图4 2011～2012年云南及周边地区岩石圈磁场变化分布图
(a)水平矢量;(b)垂直矢量;(c)磁偏角;(d)磁倾角;(e)总强度
Fig.4 The lithosphere magnetic change distribution in Yunnan and its adjacent regions from 2011 to 2012(a)horizontal vector;(b)vertical vector;(c)magnetic declination;

图5 2012～2013年云南及周边地区岩石圈磁场变化分布图<br/>(a)水平矢量;(b)垂直矢量;(c)磁偏角;(d)磁倾角;(e)总强度<br/>Fig.5 The lithosphere magnetic change distribution in Yunnan and its adjacent region from 2012 to 2013(a)horizontal vector;(b)vertical vector;(c)magnetic declination; (d)magnetic inclination;(e)total intensity

图5 2012～2013年云南及周边地区岩石圈磁场变化分布图
(a)水平矢量;(b)垂直矢量;(c)磁偏角;(d)磁倾角;(e)总强度
Fig.5 The lithosphere magnetic change distribution in Yunnan and its adjacent region from 2012 to 2013(a)horizontal vector;(b)vertical vector;(c)magnetic declination; (d)magnetic inclination;(e)total intensity

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备注

引言

1 地磁资料与计算方法

2 地磁总强度的变化

3 地磁矢量的变化

4 结论与讨论

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