大同—阳高6.1级地震前兆场分析

Analysis on Precursor Field of the Datong Yanggao Earthquake

通过对１９８９年大同—阳高６．１级地震异常的清理，发现６４项前兆异常，９项测震学异常，前兆异常主要集中在距震中１００ ｋｍ ～３００ ｋｍ 范围内、异常的演化具有明显的阶段性、早期趋势异常和临震异常均出现在震中附近地区、异常的空间展布具有不对称性等。分析了前兆场的时空强特征、前兆异常机理、孕震过程及场源关系。指出，大同—阳高地震是受华北区域应力场控制，在ＮＥＥ向主压应力作用下，ＮＮＥ向断层发生右旋走滑错动，ＮＥＥ向断裂发生左旋走滑错动的结果。

Based on precursor research of the Datong Yanggao Earthquake in 1989. The following conclusions are required, 64 item precursors anomalies and 9 item seismicity anomalies concentrated basically on 100km～300km area away the epicenter, the evolution of anomalies displays obvious stage, early term trend anomalies and short impending anomalies appears in the neighbor of the epicenter, distribution of anomalies has asymmetry character. Characteristic of space time magnitude in precursor field, mechanism of precursor anomaly, earthquake preparation, and relation between field and epicenter are analyzed. The conclusion, that the Datong Yanggao Earthquake,which occured was controlled with North China regional stress field and was influenced with main stress in NNE direction,because NNE fault took place right lateral strike slip dislocation and NEE fault took place lift lateval strike slip dislocation, was obtained.