The variation characteristics of the telluric field in the process of earthquake

According to the seismic recording data obtained in the Baodi geoelectrical station by the ZD9A geoelectric-field instrument which made in China, we s tudy the characteristics of the telluric field in the process of the earthq uake M(s)6.2 occurred in Zhangbei area of Hebei Province on the Jan, 10, 19 98. The key features and some properties of the telluric field of are discu ssed as follows. 1. Clusters of the abnormal telluric field signal occurred 36 days before the earthquake and lasted till the earthquake occurred. 2. The direction of the telluric field rotated. 3. The daily variation of the telluric field E had per 9(days) periodicity, and the amplitude \E\ showed abnormal changes. 4. The polarization of the EW component of the telluric f ield inverse. These characteristics and properties will become the pre-info rmation of precursor signal and identifying marks of prediction for short-t erm or immediate earthquakes.