华东地区中强震孕育过程中的中小地震动态演化特征

引用有关地震活动的频度面积S值方法,对华东地区1970年以来中强震前后的中小地震活动进行了研究,发现地震的S值在震前和震后的异常变化特征主要表现为:在震前S值异常为高值或低值异常,震后下降或上升;对特定区域研究发现,华东地区陆地区域的中强震的孕震区,中小地震活动的S值震前异常主要为高值,震后下降;而海域的中强震孕震区中小地震活动的S值震前主要表现为低值异常。因此,通过对华东地区中强震孕震区中小地震活动的频度面积S值方法的动态追踪,利用其变化规律可以为中强震的预测预报提供一种判定指标。

Dynamic Evolvement of Moderate Earthquakes in the Preparation of Strong Earthquakes in East China

Seismicity of the moderate earthquake before and after strong earthquakes with M≥5.0 since 1970 is studied by Frequency-Area Method(namely S-value)proposed by Wen-xuan Du.Then,a phenomenon is found that the anomaly variations of S-value before and after strong earthquakes are characterized by both commonality and individuality.The commonality is that the S-values become high anomalous values or low anomalous ones before strong earthquakes occur and they decrease or increase after strong earthquakes occur.The individuality is that in the seismogenic area of strong earthquakes on land of East China,S-values become high anomalous values before strong earthquakes occur.But in the sea of East China,S-values become low anomalous values before strong earthquakes occur.The study shows that one can make the dynamic tracing of S-value in the seismogenic area in East China and provide criteria for the earthquake prediction.