Adjoint-state traveltime tomography for azimuthally anisotropic media in spherical coordinates
Tong has proposed an adjoint-state traveltime tomography method to determine velocity heterogeneity and azimuthal anisotropy. This method, however, ignores the Earth's curvature when deriving the eikonal equation for azimuthally anisotropic media. Thus, further coordinate transformation or appr...
| Main Authors: | , , , |
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/171504 |
| _version_ | 1824454158493679616 |
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| author | Chen, Jing Chen, Guoxu Nagaso, Masaru Tong, Ping |
| author2 | School of Physical and Mathematical Sciences |
| author_facet | School of Physical and Mathematical Sciences Chen, Jing Chen, Guoxu Nagaso, Masaru Tong, Ping |
| author_sort | Chen, Jing |
| collection | NTU |
| description | Tong has proposed an adjoint-state traveltime tomography method to determine velocity heterogeneity and azimuthal anisotropy. This method, however, ignores the Earth's curvature when deriving the eikonal equation for azimuthally anisotropic media. Thus, further coordinate transformation or approximation is required to ensure the accuracy of traveltime prediction in large-scale tomography. To address this problem, we derive the eikonal equation for azimuthally anisotropic media in spherical coordinates, which naturally considers the Earth's curvature. Another key ingredient is the forward modelling algorithm, whose accuracy and efficiency dominate the numerical error and computational cost of the inversion. In this study, we apply a modified fast sweeping method to solve the eikonal equation in spherical coordinates. Two approaches, including the third-order weighted essentially non-oscillatory approximation and multiplicative factorization technique, are applied to improve the accuracy. According to the numerical experiments, this new eikonal solver achieves a second-order accuracy and is about two orders of magnitude more accurate than the commonly used first-order fast sweeping method with similar runtime. Taking advantage of the two improvements, we develop a novel eikonal equation-based adjoint-state traveltime tomography method for azimuthally anisotropic media in spherical coordinates. This method is applicable for large-scale tomography, and its performance is verified by a synthetic checkerboard test and a practical seismic tomographic inversion in central California near Parkfield. |
| first_indexed | 2025-02-19T03:17:52Z |
| format | Journal Article |
| id | ntu-10356/171504 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2025-02-19T03:17:52Z |
| publishDate | 2023 |
| record_format | dspace |
| spelling | ntu-10356/1715042023-10-30T15:35:17Z Adjoint-state traveltime tomography for azimuthally anisotropic media in spherical coordinates Chen, Jing Chen, Guoxu Nagaso, Masaru Tong, Ping School of Physical and Mathematical Sciences Asian School of the Environment Earth Observatory of Singapore Science::Geology Inverse Theory Numerical Solutions Tong has proposed an adjoint-state traveltime tomography method to determine velocity heterogeneity and azimuthal anisotropy. This method, however, ignores the Earth's curvature when deriving the eikonal equation for azimuthally anisotropic media. Thus, further coordinate transformation or approximation is required to ensure the accuracy of traveltime prediction in large-scale tomography. To address this problem, we derive the eikonal equation for azimuthally anisotropic media in spherical coordinates, which naturally considers the Earth's curvature. Another key ingredient is the forward modelling algorithm, whose accuracy and efficiency dominate the numerical error and computational cost of the inversion. In this study, we apply a modified fast sweeping method to solve the eikonal equation in spherical coordinates. Two approaches, including the third-order weighted essentially non-oscillatory approximation and multiplicative factorization technique, are applied to improve the accuracy. According to the numerical experiments, this new eikonal solver achieves a second-order accuracy and is about two orders of magnitude more accurate than the commonly used first-order fast sweeping method with similar runtime. Taking advantage of the two improvements, we develop a novel eikonal equation-based adjoint-state traveltime tomography method for azimuthally anisotropic media in spherical coordinates. This method is applicable for large-scale tomography, and its performance is verified by a synthetic checkerboard test and a practical seismic tomographic inversion in central California near Parkfield. Ministry of Education (MOE) National Research Foundation (NRF) Published version This work is funded by Minister of Education, Singapore, under its MOE AcRF Tier-2 Grant (MOE2019-T2-2-112). MN and PT are also partly supported by the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centers of Excellence Initiative (Project Code Number: 04MNS001953A620). 2023-10-27T05:22:00Z 2023-10-27T05:22:00Z 2023 Journal Article Chen, J., Chen, G., Nagaso, M. & Tong, P. (2023). Adjoint-state traveltime tomography for azimuthally anisotropic media in spherical coordinates. Geophysical Journal International, 234(1), 712-736. https://dx.doi.org/10.1093/gji/ggad093 0956-540X https://hdl.handle.net/10356/171504 10.1093/gji/ggad093 2-s2.0-85160802440 1 234 712 736 en MOE2019-T2-2-112 04MNS001953A620 Geophysical Journal International © 2023 The Author(s). Published by Oxford University Press on behalf of The Royal Astronomical Society. All rights reserved. This article may be downloaded for personal use only. Any other use requires prior permission of the copyright holder. The Version of Record is available online at http://doi.org/10.1093/gji/ggad093 or URL link. application/pdf |
| spellingShingle | Science::Geology Inverse Theory Numerical Solutions Chen, Jing Chen, Guoxu Nagaso, Masaru Tong, Ping Adjoint-state traveltime tomography for azimuthally anisotropic media in spherical coordinates |
| title | Adjoint-state traveltime tomography for azimuthally anisotropic media in spherical coordinates |
| title_full | Adjoint-state traveltime tomography for azimuthally anisotropic media in spherical coordinates |
| title_fullStr | Adjoint-state traveltime tomography for azimuthally anisotropic media in spherical coordinates |
| title_full_unstemmed | Adjoint-state traveltime tomography for azimuthally anisotropic media in spherical coordinates |
| title_short | Adjoint-state traveltime tomography for azimuthally anisotropic media in spherical coordinates |
| title_sort | adjoint state traveltime tomography for azimuthally anisotropic media in spherical coordinates |
| topic | Science::Geology Inverse Theory Numerical Solutions |
| url | https://hdl.handle.net/10356/171504 |
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