Abstract: Before the Zhangbei earthquake through the lst of Jan. 1970 to the 10th of Jan. 1998, 24 earthquakes with magnitude larger than M_L2.0 occurred in the NWW direction of Zhangbei earthquake, they were relatively concentrated along a belt. The arrival times of all the events are checked from the seismograms recorded at North China telemetric seismograph network. Additional data are used from other 5 stations of Inner Mongolia telemetric seismograph network to improve the distribution of stations used in location. Those earthquakes are relocated using the main event location approach. All events became more closely except one, forming a seismic belt. Many micro-earthquakes along Zhangbei seismic zone are recorded by 10 short period seismographs employed by Research Center of Exploration of Geophysics in February 1998. We relocated 184 micro-earthquakes using the arrival time difference between P and S waves. These micro-earthquakes together with the relocated earthquakes with magnitude large than 3.0 occurred along Zhangbei seismic zone in January 1998 outline a focal rupture belt of M6.2 earthquake. There is Zhangjiakou-Bohai rupture belt, where many strong earthquakes occurred in history, extended along the SEE direction of Zhangbei earthquake epicenter. In this paper, the results of accurate location together with the corrected focal mechanism and the distribution of macroscopic intensity are used to discuss the relationship between Zhangbei earthquake and small scale focal rupture belt and intermediate scale weak earthquake belt before the main earthquake and large scale Zhangjiakou-Bohai strong earthquake belt.

Key words: Zhangbei earthquake, Focal rupture belt, Weak earthquake belt, Accurate location