基于谱元法与Microwulf系统的汶川地震波场模拟

Simulation of Wenchuan seismic wave field based on spectral-element method and Microwulf system

谱元法属广义有限元法,可用于地震波场模拟与震源反演,但几乎不能在单台普通电脑上用于大尺度地震波场模拟。Microwulf是一种低成本、高效率的主从式便携型计算集群系统,能有效地利用个人电脑组建并行计算环境。基于三维弹性波动方程研究了谱元法基本算法,并利用谱元法和自搭建Microwulf系统对2008年汶川5.12地震波场进行模拟。模拟结果表明:(1)搭建的Microwulf系统能成功进行大尺度地震波场的谱元法数值模拟;(2)计算区域地形能引起地震波场畸变;(3)震中附近区域峰值地震动分布模式大体与发震断裂走向平行,并具有典型的上下盘效应,上盘的峰值地震动比下盘强烈;(4)与无地形模型相比,震中附近区域地形对地震动具有典型的放大效应,并且对于地震动的不同分量,其地形放大效应有所区别。

The spectral-element method that can be utilized for three dimensional simulation of seismic wave field and focus inversion is belonged to general finite-element method.But the technique is hardly suitable for simulation of large-scale seismic wave field on single common personal computer.The Microwulf is a master-slave portable computer cluster architecture,with which a cost-efficient,high performance parallel computational enviroment can be built efficiently using PCs.Firstly,the basic algorithm of spectral-element method was researched on the basis of elastodynamic equation for 3-D wave propagation.Secondly,the seismic wave field of the 12 May 2008 Wenchuan earthquake was simulated based on spectral-element method and self-built Microwulf system.The results of simulation can be summarized as follows：（1）the Microwulf system built by ourself is utilized for simulation of large-scale seismic wave field successfully based upon spectral-element method;（2）the surface topography of computational region result in distortion of seismic wave field;（3）the distribution patterns of peak ground motion in zone near epicentre are broadly parallel to coseismic fault and have marked obviously hanging-foot wall effect that peak ground motion in hanging wall are more violent than that in footwall;（4）compared with simulation result of model without topography,the ground motion are generally amplified by surface topography in zone near epicentre,and the topographic amplification effects vary with different components of ground motion.