In this paper, the main shock parameters of the March 2.1979 Guzhen Earthquake, the seismicity before the main shock and the characteristics of the earthquake sequence are studied. The results show that before the main shock, the seismic gap formed by some small earthquakes exists in a nearby region around the epicenter of the main shock. After the formation of this gap, the frequency of small earthquakes, the value of b, the strain release, etc. show anomalous changes. The velocity ratio in a certain area before the main earthquake shows anomaly too. On Feb. 17.1979, a set of earthquakes with some information about the mainshock occurred on the edge of the gap.
The survey of the aftershock sequence is introduced in this paper. And it is pointed out that the sequence is characterized by the stable source mechanism and the lower b value which are different from other general aftershock sequences.