张北6.2级地震前后地磁Z分量的日变化

利用河北省及邻省、市共１７个地磁台相对观测Ｚ分量资料，总结分析了张北６．２级地震前后的日变化。认为，一次较强地震前可能有多次异常出现，日变反向可作为中短期异常，而后出现的日变低点位移，当分界线连续在某区出现，地震可能进入短临阶段。日变反向的极值区附近和低点位移连续汇集地区可能是未来震中。对于震前出现的多次异常进行追踪预报，可能效果较好。

THE DAILY VARIATION OF GEOMAGNETIC Z COMPONENT BEFORE AND AFTER ZHANGBEI M6.2 EARTHQUAKE

The daily variation of geomagnetic Z component before and after Zhangbei M 6. 2 earthquake has been summed up and analyzed by relative observed Z component data at 17 geomagnetic stations in Hebei province and neighbouring provinces. It is considered that there may be many anomalies before a relatively strong earthquake. The reverse of the daily variation can be regarded as mid term and short term anomaly. After that daily variation low point appears,when the boundary line continuously appear in an area,the earthquake might enter the short term and imminent stage. The extreme value area of the daily variation reverse and the continuously converging area of low point shift may be the future epicenter. Trace prediction made for many anomalies occurred before earthquake may obtain a better prediction effectiveness.