邢台地震空间分布随时间变化的立体图象与地震发生过程

STEREOSCOPIC FIGURES OF THE TIME-VARIATION IN THE SPACE DISTRIBUTION OF FOCI OF THE XINGTAI EARTHQUAKES AND THEIR OCCURRENCE PROCEDURE

本文利用邢台地震台网资料研究了1966年3月邢台地震强震活动期间地震位置的空间分布随时间变化的过程。给出了一系列反映邢台地震序列强震孕育、破裂、应力场调整及地震构造的立体图象。进一步探讨了震区地壳介质中存在的障碍体与地震发生的关系。认为这种震区介质的非均匀构造所导致的邢台地震的破裂是一个沿北北东方向的断断续续的发展过程。较好地解释了几个六级以上强震的发生以及强震期后出现的中强余震“两头跳”现象。本文还对六级以上强震的破裂过程进行了讨论,并与已有结果作了对比,还考察了强震活动期间震源深度随时间变化与大震发生的关系。

In this paper,the procedure of the time-variation in focal space distribution during the high seismicity period of the Xingtai earthquakes of March 1966 is studied by using seismic data obtained by the Xingtai Local Seismic Network.A series of stereoscopic figures showing the process of seismogeny and rupture of the strong shocks,adjustment of the stress field and seismo-structure are given. A further study is made of the relation between earthquakes and barriers existing in the crustal medium of the seismic region. It is this kind of non-uniform structure in the seismic area that caused the rupture of the Xingtai earthquake to be a discontinuous growing procedure expanding along the NNE direction,through which the occurrence of several earthquakes stronger than Ms 6.0 and the phenomenon of 'flip-flops from one and to the other' of the fault of big aftershocks after the high seismicity period can be well explained.Besides,the ruptures of strong shocks bigger,than Ms 6.0 are discussed and compared with some results obtained before. And a survey is made of the relation between the variation in focal depth with time and the occurrence of big earthquake in the Xingtai region.