华东地区M_L≥4.0地震平静预测意义分析

Seismic quiescence of M_≥4.0 earthquakes in East China and its significance in earthquake prediction

用统计学上的X^2检验方法对华东地区ML≥4．0地震平静进行了统计检验，得出在较高的置信概率下可以将平静时间T≥140天作为平静异常的判别标准。总结了华东地区自1970年以来出现的平静异常，并分析了其对应中强地震的情况。研究表明，ML≥4．0地震平静异常是华东地区中强震前的一种普遍现象。62．5％的平静异常后发生了ML≥4．5地震；绝大多数平静异常前存在着地震活动的增强过程，多次活动增强后连续发生了平静异常且之后发生了Ms≥5．0地震。

In this article, we use the examination method to give statistic and examination of ML≥4.0 earthquake quiescence in East China. We get the conclusion that if the quiet time of ML≥4.0 earthquake is more than 140 days, it can be regarded as an abnormity with high probability. We summarized the ML≥4. 0 earthquake quiescence abnormity in East China since 1970 and analyzed the subsequent mid-strong earthquakes. It can be found that there were earthquake quiescence abnormity before most mid-strong earthquakes in East China. After a quiescence abnormity, in most cases （62.5%）, an earthquake of Ms≥4. 5 will occur. Before most quiescence abnormity, there is an activity abnormity. Many times after an activity abnormity, continuous quiescence ahnormity occurs and then an earthquake of Ms≥5.0 happens.