AN APPROACH TO GEOMAGNETIC PREDICTION INDEX FOR M_S≥5 EARTHQUAKES IN HEBEI PROVINCE AND ITS ADJACENT REGION
Yao Fazhang Ren Lijun Jin Yanping(Seismological Bureau of Hebei Province)
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.