【摘要】 利用地震活动性指数A(b)值系统地定量化地对青藏高原北部地区1970年以来发生的中强地震的地震活动性特征进行了分析,确定了地震活动性增强异常的判据,即A(b)值≥4.5时为高值(地震活动性增强)异常。地震活动性增强异常出现后1～3个月为发震优势时段,其次是4～6个月。该判据通过了预报效能R值评分的检验,可以用于地震预报实践。更多还原

【Abstract】 Basd on the analysis of the seismicity characteritic of the moderate or strong earthquakes in the north region of Qinghai-Tibet plateau since 1970,we think that the anomaly criterion of seismicity is the A(b)-value more than 4.5 in this paper. The anomaly mostly appears one to three months before the main shock, secondly four to six months. The criterion can be used to the prediction practice as it passed the test of the R- value of prediction efficiency.更多还原