Seismic multi-wave traveltime tomography in 3D TI media
Huang Guojiao1, Sun Jiangbing2, Bai Chaoying3, Qian Wei1
1. Department of Geology Science & Engineering, School of Earth Sciences and Engineering, Hohai University, Nanjing, Jiangsu 211100, China; 2. Jiangsu Geological Archives, Nanjing, Jiangsu 210018, China; 3. Department of Geophysics, College of Geology Engineering and Geomatics, Chang'an University, Xi'an, Shaanxi 710054, China
Abstract：The conventional anisotropic tomography is based on a weak anisotropy assumption,mainly uses the traveltime to carry out linear inversion and ignores the lateral changes in the media,so inversion results are usually not reliable.Therefore,we study a multi-wave traveltime tomography in 3D TI media.The multi-step irregular shortest path method in isotropic media is extended to 3D TI media to trace multi-wave (reflected wave,transmitted wave,and converted wave) arrivals,and the algorithm for inversion in isotropic media is used.Incorporating with the equation for phase and group velocity derivatives,5 anisotropic elastic parameters are inverted simultaneously by multi-wave traveltimes.This method does not assume that medium is weakly anisotropic whether in ray tracing and traveltime calculation,or in an inversion equation establishment,or in Jacobian matrix calculation.What is more,ray paths and traveltimes are re-tracked at each iteration,and Jacobian matrix elements are updated.So this method is suitable for multi-wave traveltime tomography in 3D TI media.Numerical test results indicate that the proposed method can improve the imaging spatial resolution.
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