A PRELIMINARY STUDY OF THE PROCESS OF DEVELOPMENT AND OCCURRENCES OF A SERIES OF RECENT STRONG EARTHQUAKES IN NORTH CHINA

This paper deals with the study of certain empirical relations regarding the development and occurrences of a series of recent strong earthquakes in North China from the view point of the broad North China region as a whole.Based on the seismological data thus accumulated, five different aspects, namely, frequency of occurrence of small earthquakes, variation of b-value with time, spatial distribution of small earthquakes, earthquake swarm activity, variation of the signs of first motion of small earthquakes, are concerned as to their relations with the occurrences of the strong earthquakes.