Seismic waveform simulation with pseudo-orthogonal grids for irregular topographic models
Seismic waveform simulation with pseudo-orthogonal grids for irregular topographic models
复制标题
不规则地形模型的伪正交网格地震波形模拟
DOI：
10.1093/gji/ggt190
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发表时间：
2013-09-01
影响因子：
2.8
通讯作者：
Wang, Yanghua
中科院分区：
文献类型：
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作者：
Rao, Ying;Wang, Yanghua
在地震波形模拟中，不规则地形（如山区）不能简化为平面。即使对于海洋地震，粗糙的水底也不能用数值方法处理为平面界面。贴体网格方案将精确地表示具有不规则地形的地球模型。由于它是一个结构化的网格，那么一个简单的有限差分格式可以被用来作为一个有效的求解器的波形模拟。通过求解泊松方程得到了网格的拟正交性。研究表明，网格的锐角应大于67 °（完全正交为90 °），网格尺寸变化率应小于5%，这样网格才具有良好的正交性，适合于波形模拟中的有限差分运算。将声波方程和吸收边界条件从物理空间转换到计算空间。波形模拟和最终层析反演使用一个现实的复杂的速度模型与曲面证明了开发的技术，适用于不规则的地形模型的有效性。
S U M M A R Y In seismic waveform simulation, an irregular topography such as mountainous areas cannot be simplified to a flat surface. Even for marine seismic, a rough water bottom cannot be treated as a planar interface numerically. A body-fitted grid scheme will accurately present an earth model with an irregular topography. As it is a structured grid, then a simple finite difference scheme can be used as an efficient solver for waveform simulation. The pseudoorthogonal property of grids is obtained by solving Poisson’s equation. Investigation reveals that grids should have the acute angles >67◦ (90◦ for completely orthogonal) and the cellsize change rate <5 per cent, so that meshes are in a good orthogonality suitable for finite difference operation in waveform modelling. The acoustic wave equation and the absorbing boundary condition are reformulated from the physical space to the computational space. Waveform simulation and eventually tomographic inversion using a realistically complicated velocity model with a curved surface demonstrate the effectiveness of developed technology that works for irregular topographic models.