2012年6月13日和7月10日华东地区部分地磁台垂直分量日变形态出现双低点异常，首次异常出现后37天，于7月20日发生江苏扬州M 4.9地震，震中位于低点位移分界线附近。分析认为，在强震前由于应力变化，引起孕震体环境中介质电导率等电磁性质发生改变，区域地磁场垂直分量日变曲线出现相位和幅度变化，说明地磁垂直分量日变双低点异常与地震的孕育和发生相关。
On July 20, 2012, the M 4.9 earthquake occurred in Yangzhou, Jiangsu Province, and double point anomalies of diurnal variation of geomagnetic vertical component are found in part of geomagnetic platforms in eastern China 37 days before the earthquake. The epicenter was near the low displacement boundary. The analysis shows that the seismogenic environment causes the changes of medium conductivity and electromagnetic properties. The phase and amplitude change of diurnal variation curve of vertical component of regional geomagnetic field indicates that the double low anomaly of geomagnetic vertical component is related to the gestation and occurrence of earthquake.
2018,39(3): 89-93 收稿日期：2017-05-31
DOI：10.3969/j.issn.1003-3246.2018.03.013
作者简介：郭明瑞(1983-),女,甘肃天水人,本科,工程师,主要从事地震监测预报工作。E-mail:545113937@qq.com
参考文献：
陈绍明.地磁日变低点位移分界线的网络分布及其与地震的关系的探讨[J].地震,1987,5:33-43.
丁鉴海,卢振业,黄雪香.地震地磁学[M].北京:地震出版社,1994:200-214.
丁鉴海,余素荣.地磁低点位移现象与昆仑山口西8.1级地震[J].西北地震学报,2003,25(1):16-21.
傅承义,陈运泰,祁贵仲.地球物理学基础[M].北京:科学出版社,1985:136-141.
胡久常,刘伟,郭明瑞,等.汶川8.0级特大地震前的地磁垂直分量日变"双低点"异常[J].地震学报, 2009,31(5):589-593.
黄雪香,余素荣.地磁低点位移异常类型特征与地震活动[J].地震,2000,20(4):39-44.
