Wavelet analysis as a tool for revealing geomagnetic precursors of the Zhangbei earthquake;

Research of the field of subsurface fluid anomalies before the Zhangbei earthquake;

Continuous monitoring of focal medium parameters and their changed before Zhangbei earthquake;

The PmP waveform data obtained from a deep seismic sounding profile, which ran through Zhangbei seismic region, were processed by means of both seismic wave complexity coefficient and frequency spectrum analysis methods, and the complexity characteristics of crust-mantle boundary beneath the studied area and its adjacent region were determined.

Study on tectonic stress tensor variation characteristics of Zhangbei earthquake series in 1998;

After the occurrence of the Zhangbei-Shangyi earthquake sequence,the hypocentral locations given by different agencies were diverse and the hypocentral distribution of the aftershocks showed no dominate orientation, and the seismogenic.

The study On the anomalies of subsurface flulds occurred before Zhangbei-Shangyi earthquake in northern part of China (110°～ 12O°E ， 38°～42°N) shows that: ①There are a　large number of subsurface fluid anoma1ies before this earthquake, and there are more physical anomalies than chemical anomalies.

The characteristics of CO2 precursory anomalies , which were observed in 9 earthquakes (M ≥4) in Houhaoyao, Huailai county for last 7 years, are analyzed- Forty-seven days before the Zhangbei-Shangyi earthquake，an anomaly of abrupt increase in CO2 in fault gas was observed.

After Zhangbei Shangyi earthquake(1998,1,10),Beijing Telemetered Seismic Network(BTSN) arranged three microseismographs in the meizoseismal area during 10～20,Jan.