地震活动因子A值及其在华北地震中短期预报中的应用

SEISMICITY FACTOR A VALUE AND ITS APPLICATION IN MID SHORT TERM EARTHQUAKE PREDICTION IN NORTHERN CHINA

综合考虑了地震活动时空强３ 个方面的震兆特征，定义了地震活动因子 Ａ值．使用１９７２ ～１９９６ 年华北地区地震资料进行空间扫描，研究中强以上地震前 Ａ 值的中短期异常变化特征．结果表明，在中短期阶段大多数地震前出现的 Ａ 值中期异常区面积明显缩小或消失，也有一些地震前１ ～３ 个月 Ａ 值异常区面积再次增大．还就用 Ａ

The seismicity factor A value is defined by synthesizing the seismicity precursors in time, space and magnitude.The seismicity data of moderate or small earthquakes during 1972～1996 in northern China are used in spacial scanning of seismicity factor A value,studying mid short term change of the A value before the earthquakes.The result shows that in mid short term, the mid term anomaly zones of A value that appeared about 2～3 years before a lot of strong earthquakes may contract or disappear obviously, and the zones may obviously extend again about 1～3 months before some earthquakes. Some problems about mid short term earthquake prediction by using the A value are also disscused.