Abstract: It is assumed that the continental crust, such as North China crust behaved as a elastic plate cutted by faults with various trends. Due to the complexity of crustal structure in the course of crustal movement would be formed a lot of stress-concentrated points where are clustered the most precursor phenomena. Some of those points would become sources of future earthquakes. In this paper an attempt is made to explain two kinds of phenomena by concept of multipoints stress field, that is, 1) there exist an isolated precursory-concentrated area long before the earthquake occurrence and 2) the strong earthquakes take place continuously and frequently in a short period, for instance the series of strong earthquakes in North China.

摘要： 不连续介质中应力的分布是不均匀的,其中应力集中点发育情况的一般问题,在固体力学中已有相当的研究。地壳中存在许多不连续界面,再受垂向和斜向断裂的切割,其不连续的特点更为明显,这在地质构造研究中已引起广泛注意。但在研究地震的蕴育问题时,许多概念往往还仅局限在连续体中考虑问题,如把震源看成是单一的应力集中点,把前兆场视为"单点场"所决定的,认为前兆的强度和出现的先后都是由震源向外发展的。