求解SH波方程的ONAD方法及SH波在地幔中的传播模拟
摘要
优化的近似解析离散化(ONAD)方法是近年来发展的一种新方法.与被普遍使用的有限差分方法相比,这类方法充分利用了位移梯度所包含的波场信息,使得该类方法在粗网格下能够有效地压制数值频散.本文给出求解二维球坐标系下SH波方程的ONAD方法.为了调查球坐标系下该算法的精度和计算效率,选取均匀介质和IASP91非均匀介质模型,分别给出了这两种情况下ONAD方法的计算结果,并与其他算法做了比较.结果表明,ONAD方法在求解球坐标系下SH波方程时具有弱数值频散、储存量小以及计算速度快的优点.作为应用,本文模拟了SH波在地表和地幔边界(CMB)之间的传播,得到了不同时刻的波场快照以及合成地震记录,并通过对波场快照和地震记录的分析,研究了SH波在地幔中的地震传播.
引文
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2Chaljub E,Tarantola A.Sensitivity of SS precursors to topography on the upper-mantle660-km discontinuity.Geophys Res Lett,1997,24:2613-2616
3Igel H,Weber M.P-SV wave propagation in the Earth’mantle using finite-differences:Application to heterogeneous lowermost mantle structure.Geophys Res Lett,1996,23:415-418
4Nissen-Meyer T,Fournier A,Dahlen F A.A2-D spectral-element method for computing spherical-earth seismograms.—I.Moment-tensor source.Geophys J Int,2007,168:1097-1093
5Alterman Z,Aboudi J,Karal F C.Pulse propagation in a laterally heterogeneous solid elastic sphere.Geophys J R Astron Soc,1970,21:243-260
6Dablain M.The application of high-order differencing to the scalar wave equation.Geophysics,1986,51:54-66
7Graves R W.Simulating seismic wave propagation in3D elastic media using staggered-grid finite differences.Bull seism Soc Am,1996,86:1091-1106
8Yang D H,Teng J W,Zhang Z J,et al.A nearly-analytic discrete method for acoustic and elastic wave equations in anisotropic media.Bull Seism Soc Am,2003,93:882-890
9Yang D H,Lu M,Wu R S,et al.An optimal nearly-analytic discrete method for2D acoustic and elastic wave equations.Bull Seism Soc Am,2004,94:1982-1992
10Yang D H,Peng J M,Lu M,et al.Optimal nearly analytic discrete approximation to the scalar wave equation.Bull Seism Soc Am,2006,96:1114-1130
11Lapwood E R,Usami T.Free Oscillations of the Earth.Cambridge:Cambridge University Press,1981
12Kenneth B L N,Engdahl E R.Traveltimes for global Earthquake location and phase identification.Geophys J Int,1991,105:429-465
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