Abstract:
After the comparative analysis to the data of the geomagnetic moving survey and the correlative station observation in Hebei province and its vicinity in 1986-1989 September before Datong-Yanggao Ms6.1 earthquake, it is considered that the bigger deviations measured by geomagetic moving survey at Zhangjiakou, Hualai, etc, in 1989 before the earthquake may be owing to the limitation of the surveying way itself and the inhomogeneous of the external field, Therefore, it is not suitable to regard it as the preearthquake anomalous variation. Calculation have been made to the data, and the quadratic multinomial tendency sulface analysis is conducted to the calculated mean annual variation rates relative to Wanxian. The analysis result suggests that on the background of normal variation in a large scale, there is a negattive deviation area, centered at the epicenter of Datong-Yanggao Ms 6.1 earthquake, this may be correlated to the geomagnetic field variation caused by the stress field before the earthquake.