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Ultra Efficient Methods of Seismic Wave Modeling for Waveform Tomography

用于波形层析成像的超高效地震波建模方法

基本信息

批准号：
16540389
负责人：
TAKENAKA Hiroshi
金额：
$ 2.3万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16540389/
关键词：
seismic wave synthetic seismogram finite-difference method viscoelastic medium Q plane wave 2.5D 地震波動計算法

项目摘要

Waveform tomography is one of the highest resolution methods for imaging the Earth's interior. Application of the waveform tomography to real data requires huge number of computations of 3D seismic wavefields. For such iterative calculations of synthetic seismograms with limited computer resources, a fast and accurate modeling method is needed. For this purpose, we developed the following efficient numerical methods for modeling seismic waveforms :1. Quasi-spherical approach for seismic wave propagation in a 2D slice through a global earth model with lateral heterogeneity : The elastodynamic equation for spherical coordinates is not solved in the conventional spherical domain but instead in a "quasi-spherical domain" using the finite-difference method (FDM). This approach can correctly model 3D geometrical spreading effects with computational times and memories comparable to 2D methods, and can treat asymmetric structure about the vertical axis including the source.2. Axisymmetric modeling : It can also correctly model geometrical spreading effects in 3-D within computational resources comparable to 2-D modeling. However, in the previous works with the axisymmetric modeling, seismic sources were restricted to axisymmetric sources such as an explosive source. In this study, we proposed an implementation of an arbitrary moment tensor point source to axisymmetric modeling using the FDM.3. Efficient FDM algorithm for modeling seismic plane waves for vertically heterogeneous "viscoelastic" media : It can model frequency-dependent anelastic (Q) effects. The scheme uses a 1D grid, which causes a significant reduction in computation time and memory requirement compared to the corresponding 2D or 3D computations.

波形层析成像是对地球内部进行成像的最高分辨率方法之一。将波形层析成像应用于真实的数据需要大量的三维地震波场计算。对于这种在有限计算机资源下进行的合成地震记录迭代计算，需要一种快速准确的模拟方法。为此，我们开发了以下有效的数值方法来模拟地震波形：1。通过具有横向不均匀性的全球地球模型的2D切片中地震波传播的准球面方法：球坐标的弹性动力学方程不是在传统的球面域中求解，而是使用有限差分法（FDM）在“准球面域”中求解。该方法可以正确地模拟三维几何扩散效应，计算时间和内存与二维方法相当，并且可以处理包括源在内的关于垂直轴的非对称结构.轴对称建模：它还可以在与2-D建模相当的计算资源内正确地建模3-D中的几何扩散效应。然而，在以前的工作与轴对称建模，地震源被限制为轴对称源，如爆炸源。在这项研究中，我们提出了一个任意的矩张量点源的实现轴对称建模使用FDM。垂直非均匀“粘弹性”介质地震平面波建模的高效FDM算法：它可以模拟频率相关的滞弹性（Q）效应。该方案使用1D网格，这导致了显着减少计算时间和内存需求相比，相应的2D或3D计算。