【摘要】 分析了华北北部 2 0世纪 70年代初以来的断层形变资料。结果表明 :震前断层活动存在明显的阶段性特征 ;短临阶段断层形变异常主要形态有两种 :一种是在α、β相后的γ相短临异常 ,这种异常一般在近源区出现 ;另一种是较大幅度的突跳型短临异常 ,这种异常一般在远源区出现 ,这些都是断层形变前兆由中期过渡到短期的明显标志 ;断层形变短临异常有从外围向震中迁移的特征 ;唐山地震前出现γ相短临异常的比例高于大同和张北地震 ,主要表现为在中期趋势积累背景上的反向 ;3次强震前α、β、γ相异常场地的分布具构造控制特征 ;强震前场地断层异常活动存在象限性分布特征 ,且与震源机制解的结果基本一致更多还原

【Abstract】 The cross-fault deformation in the north of North China since the early 1970’s has been analyzed systematically in this paper. The results show as follows:The fault movement before earthquakes has obvious staged characteristics. There are two forms of the fault deformation anomaly in short-impending stage: one is the %γ% phase after %α,β% phases, which occurs nearby the source region; the other is a significant abrupt jump, which is in the outer circle of source region. Both of them are obvious symbols of the transition from medium term to short term of the fault deformation anomaly. The fault deformation anomaly has the characteristic that it moves from the outer circle to the source region. The proportion of anomaly of %γ% phases in Tangshan earthquake is bigger than that in Datong and Zhangbei earthquake and the fault deformation anomaly in short-impending stage is contrary to the trend of medium-term precursory anomalies. The distribution of cross-fault deformation measurement sites with anomaly of %α,β% and %γ% phases before the 3 strong earthquakes has the characteristic of tectonic control. The characteristic of quadrantal distribution of the fault movement exists actually in earthquake-generating process, which is almost consistent with focal-mechanism solution.更多还原