大同盆地与晋冀蒙三省交界地区在区域中强地震前b值时间变化特征浅析

Time variation characteristics of b Value before Regional Medium Strong Earthquakes in Datong Basin and Juncture Area of Shanxi,Hebei and Inner Mongolia

利用晋冀蒙三省交界地区1972—2000年地震资料,用最小二乘法进行b值时间扫描计算,研究得出晋冀蒙三省交界区b值背景值在0.263~0.861之间,平均值为0.429;大同盆地b值背景值在0.229~0.931之间,平均值为0.493。区域发生的中强地震与2个研究区的b值时序曲线异常有4种对应关系。在研究时段内的几个震例中,地震与b值的时间关系以先高值异常,异常结束后发震为主要特征。

By using the earthquake data in juncture area of Shanxi,Hebei and Inner Mongolia provinces from 1972 to 2000,time scanning of b value is calculated by least square method.The study shows that the b value of background value in juncture area of Shanxi,Hebei and Inner Mongolia provinces is between 0.263-0.861,the average value is 0.429.And the b value of background value in Datong Basin is between 0.229-0.931,the average value is 0.493.Regional medium strong earthquakes and time-sequence curve anomalies of b value in the two regions have 4corresponding relations.Several examples in the study period indicate that the relationship of earthquake and the b value is high value anomaly before earthquake.