河北省及其邻区M_s≥5地震地磁预报指标的探讨

AN APPROACH TO GEOMAGNETIC PREDICTION INDEX FOR M_S≥5 EARTHQUAKES IN HEBEI PROVINCE AND ITS ADJACENT REGION

本文利用基本磁场(F、Z)台站观测资料,通过仪器差、墩(点)位差等改正,并经一定的数据筛选,再用相关改正法消除外场影响等处理,结果除菏泽M_s5.9地震外,在唐山M_s7.8、丰镇M_s5.8、隆尧M_s5.8、任县M_s5.3地震前,都出现了5个月至一年多的总强度异常,变化幅度为6.0—9.1nT,垂直分量(Z)资料一般亦有同步反应.因此,基本磁场(F、Z)资料用于监视中强地震是有效的,监视距离以台站为圆心50至100公里范围内。但未出现临震异常,从而认为,河北省及其邻区,基本磁场资料,只适用于趋势预报。

This paper uses the data of basic magnetic field (F, Z) observed at stations, through the correction of instrumental and pier position errors and after a certain data screening, the effect from external field is eliminated by the correlative correction. The result indicates that there appeared the total magnetic intensity anomaly, the rangeability is 6.0-9.1nT, and the vertical component (Z) of the magnetic field also show synchronous response five months to over one year before Tangshan MS7.8, Fengzhen MS5.8, Longyao MS5.8 and Renxian MS5.3 earthquakes with the exception of Heze MS5.9 earthquake. Therefore it is valid that the basic magnetic field (F, Z) can be used to monitor moderate-strong earthquakes but it did not show any imminent anomaly, the monitoring distance is 50-100km to the station. Thus it is considered that the data of the basic magnetic field can only be applied to the tendency prediction in Hebei province and its adjacent region.