THE HYPOCENTRAL DISTRIBUTION OF THE XINGTAI(邢台) EARTHQUAKE SERIES, TECTONIC STRESS FIELD AND THE PROCESS OF EARTHQUAKE OCCURRENCES
HE ZHI-TONG XIE TING(Institute of Geophysics, Academia Sinica)
In March 1966, five successive strong earthquakes of magnitude Ms≥6 occurred in the xingtai region of the Hopei Province, China, Among them, the earthquake occurred on March 22 near Dongwang (东汪) of the Ningjin xian (宁晋县) has the largest magnitude (Ms=7.3). In this paper, the hypocentral space distribution of these strong earthquakes and their relatively large aftershocks is discussed. Then, using known focal parameters of some of these earthquakes, an analysis of the form of recent tectonic movement of the region and the general stress pattern before the earthquake series has been made. Finally, it is attempted to explain the process of migration and the mutual triggering effect of the earthquakes in the light of the above analysis.