THE CHARACTERISTICS OF THE SEISMICITY AROUND THE JUNCTURE OF SHANXI, HEBEI, SHANDONG AND HENAN PROVINCES

Basing on the analysis of the recent and histroical seismic activity anoand the junetre of Shanxi, Hebei, Shandong and Henan provinces, the characteristics of the seismicity in this area have been shown. It is suggested that a strong event or a groip of the strong shocks is the reflection of the stress increasing process. Based on this, seismic activity pattern and the developing process before 1830 Cixian 7.5 and 1937 heze 7.0 earthquakes have been analysised. It is obtained that the process from peripheral scismic activity (or seismic belt) in large scale to centralized activity of the cluster in small scale has been undergone. Then, the echo relation betwesa Heze earthquake and Tangshang earthquake has been discussed by typical shocks. It is interesting that the echo occurs in the seismically quiet period in North China. This situatioa should be noticed in the trend analysis of the funture seismicity. The areas that need to be strenghened in detection in recent have been suggested.