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| Seismic traveltime inversion of 3D velocity model with triangulated interfaces |
| Fei Li1,2, Tao Xu1, Minghui Zhang1,2, Zhenbo Wu1,2, Chenglong Wu1,2, Zhongjie Zhang1, Jiwen Teng1 |
1 State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
2 University of Chinese Academy of Sciences, Beijing 100049, China |
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Abstract Seismic traveltime tomographic inversion has played an important role in detecting the internal structure of the solid earth. We use a set of blocks to approximate geologically complex media that cannot be well described by layered models or cells. The geological body is described as an aggregate of arbitrarily shaped blocks, which are separated by triangulated interfaces. We can describe the media as homogenous or heterogeneous in each block. We define the velocities at the given rectangle grid points for each block, and the heterogeneous velocities in each block can be calculated by a linear interpolation algorithm. The parameters of the velocity grid positions are independent of the model parameterization, which is advantageous in the joint inversion of the velocities and the node depths of an interface. We implement a segmentally iterative ray tracer to calculate traveltimes in the 3D heterogeneous block models. The damped least squares method is employed in seismic traveltime inversion, which includes the partial derivatives of traveltime with respect to the depths of nodes in the triangulated interfaces and velocities defined in rectangular grids. The numerical tests indicate that the node depths of a triangulated interface and homogeneous velocity distributions can be well inverted in a stratified model.
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Received: 02 September 2013
Published: 30 November 2013
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| Fund:the Ministry of Science and Technology of China (2011CB808904), the National Natural Science Foundation of China (Nos. 41021063, 41174075, 41004034, 41174043, and 41274090) |
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Corresponding Authors:
Fei Li
E-mail: lifei@mail.iggcas.ac.cn
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