近断层地震动最强速度脉冲方向分量特性研究

Characteristics of near-fault velocity pulses in the strongest pulse orientation

为了研究速度脉冲型地震动的最强速度脉冲方向分量与垂直或平行断层方向分量之间的特性差异,本文采用多分量速度脉冲识别方法从NGA-West2强震动数据库的236组近断层地震动速度脉冲记录中提取出最强速度脉冲方向分量,对其脉冲参数随震级M_W和断层距R变化的统计关系式进行了回归分析,并对比了最强速度脉冲方向分量与垂直或平行断层方向分量之间的特性差异。研究结果表明:当R<30 km时,最强速度脉冲方向分量的脉冲幅值预测值较垂直或平行断层方向分量的预测值大,而当R>30 km时,两种分量的脉冲幅值预测值相差不大,可以忽略;当M_W≤7.5时,最强速度脉冲方向分量的脉冲周期预测值比垂直或平行断层方向分量的预测值大,而当M_W>7.5时,两种分量的脉冲周期预测值差异不大,可以忽略。

In order to explore the characteristic difference of velocity pulse between the strongest velocity pulse component and those of the vertical fault or parallel fault component,the strongest pulse orientation components were extracted from 236 groups of near-fault ground motion velocity pulse records of the strong ground motion database NGA-West 2 by using the multi-components velocity pulse identification method. Then,relationships of the pulse amplitude and the period with magnitude and fault distance were also analyzed by regression.Finally,characteristics of pulses in the strongest pulse orientation and in vertical or parallel fault orientation were compared. The following conclusions can be made：When the fault distance is less than 30 km,the predicted value of the peak ground velocity in the strongest pulse orientation is larger than that in the vertical or parallel fault orientation. However,with the increase of the fault distance,the difference of the peak velocities in the two orientations can be neglected.The pulse period is smaller in the strongest pulse orientation than in the vertical or parallel fault orientation for records with magnitude MW smaller than 7.5,whereas when magnitude MW is greater than 7.5,the difference of the pulse period between the two orientations can be ignored.