盆地对三分量地震动持时的影响初探

Primary Exploration of the Basin Effect on Significant Duration

利用关东盆地及其周边KiK-net台网井上台站记录的2004-2017年15次中强地震(矩震级为5.1~6.9级)构建三分量记录显著持时Ds数据库。针对该数据库,基于残差分析方法和3种水平向地震动持时参数预测方程,计算并给出事件间残差和事件内残差及其随不同类别参数的变化。在此基础上,初步探讨了水平向地震动持时预测方程应用于预测竖向地震动持时的可行性及盆地对三分量地震动持时的影响。研究结果表明,对于震源距和场地V相当的情况,盆地内台站持时普遍大于盆地外台站持时,盆地内、外台站竖向地震动持时均大于水平向地震动持时;3种预测方程均可实现对盆地外台站水平向地震动Ds的合理估计,但在一定程度上低估了盆地内台站的水平向地震动Ds;3种预测方程均无法直接应用于竖向地震动持时预测。

Based on the three-component records of MW 5.1~MW6.9 earthquake events recorded by KiK-net of Japan Strong Motion Observatory Network from 2004 to 2017, this paper constructs the Ds5-95 duration database of 15 strong crustal earthquakes in the Kanto basin. Further, the inter-event residuals and intra-event residuals of the duration database are calculated based on the residual analysis method and three kinds of duration prediction equations, and their changes with different parameters are also discussed. The prediction level of vertical earthquake ground motion duration based on duration prediction equation for horizontal ground motion and the influence of basin on three component earthquake records duration are analyzed. The results show that the duration of earthquake ground motion for inside-basin stations is greater than that of outside-basin stations, and the duration of vertical earthquake ground motion is greater than that of horizontal ground motion, thus, the influence of the basin effect on the duration can not be ignored;Three kinds of duration prediction equations can realize the reasonable estimation of horizontal earthquake ground motion Dsduration for outsidebasin stations, but to a certain extent, horizontal earthquake ground motion Dsduration is underestimated for inside-basin stations;Three kinds of duration prediction equations can not be directly applied to the estimation of vertical earthquake ground motion duration.