汶川震区地震动三维地形效应的谱元法模拟  

Simulation of three-dimensional topographic effects on seismic ground motion in Wenchuan earthquake region based upon the spectral-element method

作　　者：胡元鑫[1] 刘新荣[1,2] 罗建华 张梁[1] 葛华[4] 

机构地区：[1]重庆大学土木工程学院,重庆400045 [2]中国人民解放军后勤工程学院建筑工程系,重庆401311 [3]重庆市地质矿产勘察开发局南江水文地质与工程地质队,重庆401121 [4]中国地质调查局成都地质调查中心,成都610081

出　　处：《兰州大学学报（自然科学版）》2011年第4期24-32,共9页Journal of Lanzhou University(Natural Sciences)

基　　金：国家自然科学基金创新群体基金项目(50621403);中国地质调查局项目(1212010914011)

摘　　要：针对三维波动弹性动力方程推导了谱元法算法,并考虑三维真实地形及介质的衰减特性,基于并行计算环境采用谱元法和ASTER DEM模型对5.12汶川地震动的地形效应进行了模拟.模拟结果表明陡峻地形对地震波两个水平分量的影响要大于对竖向分量的.震中附近区域的PGA最大值为671cm/s2,高PGA区多分布于山顶及山脊区域.与平坦地形相比,PGA相对地形放大系数为-12%～110%,不同地点的z向速度分量波幅遵循峰顶、山脊得到放大或沟谷得到降低的模式.这说明与已有的二维概化模型计算结果相比,三维真实地形对地震动的影响比二维概化模型更为复杂.The effects of topography on seismic ground motion of Wenchuan earthquake were simulated based upon elastodynamic equation for 3D wave propagation,the spectral-element method,ASTER DEM model and parallel computation environment and incorporated realistic 3D topography and attenuation of media.The simulated results show that topographic effects due to great rough terrain on two horizontal components of seismic wave are bigger than those on vertical component.The max PGA value in zone near epicentre is 671 cm/s2,while large PGA values are almost located near mountain tops and ridges.Compared with the model without topography,the relative topographic amplification factors of PGA in the zone near the epicentre are -12%～110%,while the z velocity component at different sites are in accordance with the pattern of amplification on mountain tops and ridges,and there is a decrease in valleys and brooks.It can be concluded that the effects of 3D realistic topography on seismic ground motion are more complex than those of the existing 2D generalized model.

关 键 词：地震动 地形效应 谱元法 汶川地震 

分 类 号：P315[天文地球—地震学]