山西大同—阳高6.1级地震前地震活动特征

STUDY ON THE CHARACTERISTICS OF SEISMICITY BEFORE THE DATONG—YANGGAO MS 6.1 EARTHQUAKE

本文根据孕震空区、波速比、地震发生方式参数P值的空间扫描、震群活动和N值、b值、c值等地震活动性预报指标的变化,分析了大同一阳高6.1级地震前的地震活动性特征。结果表明上述异常大体自1986年下半年陆续出现,有些指标还出现了明显的同步变化。指出该孕震空区晚期所出现的逼近地震到主震发生之间的时间比震例总结所得到的时间要长些。本文最后提出了一条自南黄海、射阳到大同的地震活动带,该带有可能成为华北近年来中强以上地震活动的重要场所。

In this paper, based on some predicting criteria of seismicity, such as preparation gap,seismic velocity ratios, spatial scanning of values, activity of earthquake swarm, N values, b values, C values etc., the characteristics of seismicity before the Datong-Yanggao Ms 6.1 earthquake are analyzed. The results show that, the anomalies of these criteria aboveme-tioned occurred in succession in the later six months in 1986. It is pointed out that the dura-tion between the imminent earthquake appeared in the later period of the prepatation gap and the mainshock is longer than that obtained in some earthquake cases. Finally in this paper,we present a seismically active belt from south Yellow Sea, through Sheyang to Datong,which is possible to be a important zone in which some moderate and strong earthquakes may occur next years.