山东东部及近海地区中等以上震例前地震活动性参数群体异常研究

A Study on Group Anomalies of Seismic Activity Parameters before Moderate Earthquakes in the Eastern Shandong and Its Offshore Areas

对1975年以来山东东部及近海地区16次ML≥4.7级地震前的地震学参数群体异常进行了研究。回顾性检验表明,地震活动性单项参数中,反映地震强度、频度及与强度、频度有关的地震参数异常在本区的中强地震预测中较为有效。参数的时程曲线中Et、Qp和η值一般表现为低值或由高值转为下降异常形态,其余参量多数显示为高值异常。在20余项地震活动性参数中经检验拣择出14项对本区中强地震预测效果较为明显的参数,并确定了这些参数对于本区中强地震预测的群体异常指标:若14项参数中10项以上出现了异常,本区有发生5级以上地震的危险。

In this paper,the group anomalies of seismic activity parameters appeared before sixteen earthquakes of ML≥4.7 in eastern Shandong and its offshore areas since 1970 are studied.The results show that seismic activity parameters related to seismic intensity and frequency are more sensitive to moderate earthquake.Generally,the values of Et,Qp and η are in low level or drop from high level before moderate earthquake,while the values of the other seismic parameters are in high level.Fourteen seismic activity parameters sensitive to moderate earthquake are selected from twenties,and the group abnormal indexes of which are determined.If more than ten parameters of the fourteens show abnormal,the area may be at the risk of occurring earthquake of ML≥5.0.