华北区域性地磁低点位移异常特征

利用河北及邻省共17个台站的地磁Z分量资料,统计分析了地磁低点位移的异常特征。研究结果表明: ①异常并不与静、扰日存在明显的依赖关系;②异常具有季节性变化,冬、夏季最多,秋季次之,春季最少;③异常偏离中午的最大时间大多在下午及偏西方位;④有震异常占总异常35%,异常后1个月内发震的占有震异常47%。并认为一次较强地震前,日变低点位移可能有多次异常出现,利用文中提出的地磁交汇法进行追踪预报效果较好。

Characteristics of regional geomagnetic low- value displacement anomalies in North China

The characteri stics of geomag netic low-value displacement anomaliessta tistically analyzed by using the geomagnetic Zcomponent data from Hebei and neig hbo ring prov inces′17 observ atio n statio ns. The study results show that: ① The anomalies do not have obviously dependent relations with calm or noisy day. ② Anomalies have seaso nal changes—i t cha nges most in winter and summer, the seco nd in autumn, and the less in spring. ③ The maximum time that anomalies deviate from noon is mostly in the af ternoon and in the west direction. ④ Anomalies correspo nding to earthquakes are 35% of the total anomalies, and the anomalies that an earthquake occurs in a month are 47% of them. The low-value displacement anomalies in daily chang es may appear many times, and we can get good prediction effect using the method of geomagnetic conv ergence presented in thispaper.