Computation of complete synthetic seismograms for laterally heterogeneous models using the Direct Solution Method
Computation of complete synthetic seismograms for laterally heterogeneous models using the Direct Solution Method
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DOI：
10.1111/j.1365-246x.1997.tb00983.x
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发表时间：
1997-07
影响因子：
2.8
通讯作者：
P. Cummins;N. Takeuchi;R. Geller
中科院分区：
文献类型：
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作者：
P. Cummins;N. Takeuchi;R. Geller
摘要 我们使用直接解法 (DSM) 以及 Geller & Takeuchi (1995) 和 Takeuchi, Geller & Cummins (1996) 导出的修改算子来计算球坐标中横向异质模型的完整合成地震图及其偏导数。本文提出的方法非常适合对三维地球结构进行波形反演。弱扰动的假设是不必要的，尽管这种近似在使用适当时可以大大提高计算效率。给出了一个示例计算，其中针对轴对称模型计算环形波场，该模型的速度取决于深度和纬度，但不取决于经度。使用 DSM 计算的波场与通过追踪光线计算的波前非常吻合。为了证明我们的算法不限于对球对称结构的弱非球面扰动，我们考虑速度结构的纬度相关部分非常强的模型。
SUMMARY We use the Direct Solution Method (DSM) together with the modified operators derived by Geller & Takeuchi (1995) and Takeuchi, Geller & Cummins (1996) to compute complete synthetic seismograms and their partial derivatives for laterally heterogeneous models in spherical coordinates. The methods presented in this paper are well suited to conducting waveform inversion for 3-D Earth structure. No assumptions of weak perturbation are necessary, although such approximations greatly improve computational efficiency when their use is appropriate. An example calculation is presented in which the toroidal wavefield is calculated for an axisymmetric model for which velocity is dependent on depth and latitude but not longitude. The wavefield calculated using the DSM agrees well with wavefronts calculated by tracing rays. To demonstrate that our algorithm is not limited to weak, aspherical perturbations to a spherically symmetric structure, we consider a model for which the latitude-dependent part of the velocity structure is very strong.