THE TECTONIC FEATURE OF THE FAULTS IN ZHANGBEI EARTHQUAKE REGION

Zhangbei M6.2 earthquake occurred in the area of northern Zhangjiakou dam in January 10, 1998.The epicenter is covered by effusive basalts of Miocene and Pliocene and the stratum of Quaternary(0~3m).The detection of electromagnetic wave remote sensing shows three group faults in NE, NNE and NW direc tion respectively exist in the area.The field geological survey testifies that the NWW Xiaoshuiquan-Manjing fault, the NS Dongshuiquan fault and the subfault of EW Chicheng-Shangyi fault all broke these stratums evidently.Thermoluminescent dating shows the lates active ages of the faults are respectively 0.167 Ma, 0.203 Ma and 0.143 Ma.The earthquake occur in the vicinity of the intersection of the three group faults.The NWW Xiaoshuiquan Manjing fault is the seismogenic fault.