【摘要】 基于汶川地震断层距150 km内56个台站三分量加速度记录分析地震动重要持时的特征,并建立了持时与断层距的拟合关系。与已建立的持时公式比较,以往分析结果都大大低估了汶川地震动持时。近断层特征对地震动持时有显著影响。断层距小于30 km,上盘和下盘场点的持时明显低于平均水平;断层距大于30 km,地震动持时受到下盘效应的影响,持时较长。破裂方向性效应引起地震动持时在垂直断层方向与水平方向上的差异,同时断层破裂前方向场点的地震动持时较短,比破裂后方向场点的持时小近一倍。更多还原

【Abstract】 56 stations within 150 km to causative fault surface are used as database to analyze the characteristics of the durations of ground motions during the Wenchuan earthquake.A simple attenuation relation in terms of rupture distance is proposed and compared with some available predictions.Previous equations of duration largely underestimated the durations of ground motions for this earthquake.The near-fault characteristics have impact upon the durations.Within rupture distance 30 km,the durations on hanging wall and footwall are lower than the attenuation relation.For the rupture distance larger than 30 km,the durations are strongly influenced by footwall effect.The differences of durations resulting from directivity effects between fault normal and fault parallel are found.Durations of ground motions close to rupture fault are significantly different between the forward and backward direction,and this difference reaches nearly 2 times on average.更多还原