Abstract: A earthquake series is referred as the events being successively occurred in a definite time and in the same seismic area. These events are characterized by the common developing process and an unified evolutional history of precursory field. We consider that the seismic precursory field is nothing but a regional field beyond a certain source region.For the North China fault block region can be recognized two earthquake series, Xingtai-Bohai and Haicheng-Tangshan series ever since the occurrence of Xingtai earthquake of 1966 to the year of 1978. The anomalies in the precursory field of this series started in 1972, after 1976 Tangshan earthquake it has been gradually becoming quiet. With regard to the developmental process of this field and its spatial distribution can be distinguished following five anomaly-development periods and relevant six stages.1. The primary period (A), during which the precursory field is developed from the stage in a scattered form (Ⅰ) to a divergent stage on a large scale (Ⅱ).2. Accelerated period (B) before Haicheng earthquake, during which the precursory field migrates northward entering into a convergent stage (Ⅲ) in the extent.3. Developing period (C), during which the precursory field enters into a rediver-gent stage (Ⅳ).4. Transitional or accelerated period before the Tangshan earthquake (D), during which the precursory field enters into a reconvergent stage(Ⅴ).5. Impending period before the Tangshan earthquake (E), during which the precursory field enters into a divergent stage (Ⅴ).It is suggested that the formation and development of the precursory field are closely related to the conjugated shear-rupturing network, and the distribution and development of anomalous points or zones are constrained by slipping of conjugated shear-ruptures and stress concentration at the various tectonic position. Consequently, the precursory phenomena would not be limited in the source area and its neighbouring regions, and the multi-anomalous regions (zone) are formed.Finally, the relationship of the regional precursory field with the earthquake prediction is studied. In general the regional precursory field does not imply only one event, perhaps an earthquake series, and the precursory extent has a certain relation to the magnitude of an event. To discriminate the location of one shock from the earthquake series it is necessary to pay attention to the spatial changes in the precursory field, such as the migration and convergence of anomalies. On the background of regional precursory field, the macroscopic anomalies in a great amount and concentrated form together with some abrupt anomalies can be taken as a precursory signal of a big imminent earthquake.

摘要： 一个地震系列是指一定时间内,在同一地震区中连续发生的若干地震事件。它们有一个共同的孕育过程,因而具有统一的前兆场的演化历史。地震前兆场是一个区域场,而不只局限于某个震源区的变化。根据本文所定义的地震系列和前兆场的概念,研究了海城-唐山地震系列孕育过程中地震前兆场的时空演化特征。它可以分为不同的阶段,每个阶段的异常特征及空间分布特点不同。在此基础上,讨论了它们与地质构造的关系及其对地震预报的意义,包括前兆场的区域大小与震级、前兆场的空间变化过程与发震地点的关系及地震发生前的短临前兆标志。