Calculating qP-wave traveltimes in 2-D TTI media by high-order fast sweeping methods with a numerical quartic equation solver

Han, Song1; Zhang, Wei2; Zhang, Jie1

2017-09

10.1093/gji/ggx236

GEOPHYSICAL JOURNAL INTERNATIONAL   影响因子和分区

0956-540X

1365-246X

A fast sweeping method (FSM) determines the first arrival traveltimes of seismic waves by sweeping the velocity model in different directions meanwhile applying a local solver. It is an efficient way to numerically solve Hamilton-Jacobi equations for traveltime calculations. In this study, we develop an improved FSM to calculate the first arrival traveltimes of quasi-P (qP) waves in 2-D tilted transversely isotropic (TTI) media. A local solver utilizes the coupled slowness surface of qP and quasi-SV (qSV) waves to form a quartic equation, and solve it numerically to obtain possible traveltimes of qP-wave. The proposed quartic solver utilizes Fermat's principle to limit the range of the possible solution, then uses the bisection procedure to efficiently determine the real roots. With causality enforced during sweepings, our FSM converges fast in a few iterations, and the exact number depending on the complexity of the velocity model. To improve the accuracy, we employ high-order finite difference schemes and derive the second-order formulae. There is no weak anisotropy assumption, and no approximation is made to the complex slowness surface of qP-wave. In comparison to the traveltimes calculated by a horizontal slowness shooting method, the validity and accuracy of our FSM is demonstrated.

Numerical solutions Computational seismology Seismic anisotropy

SCI ; EI

英语

通讯

National Earthquake Reporting Research Program of China Earthquake Administration[201408018]

Geochemistry & Geophysics

Geochemistry & Geophysics

WOS:000411213800021

OXFORD UNIV PRESS

20175004532115

Anisotropy ; Finite difference method ; Numerical methods ; Seismology

Seismology:484 ; Earthquake Measurements and Analysis:484.1 ; Numerical Methods:921.6 ; Physical Properties of Gases, Liquids and Solids:931.2

GEOSCIENCES

Web of Science

1.Univ Sci & Technol China, Sch Earth & Space Sci, Lab Seismol & Phys Earths Interior, Hefei 230026, Anhui, Peoples R China
2.Southern Univ Sci & Technol, Dept Earth & Space Sci, Shenzhen 518055, Peoples R China

Han, Song,Zhang, Wei,Zhang, Jie. Calculating qP-wave traveltimes in 2-D TTI media by high-order fast sweeping methods with a numerical quartic equation solver[J]. GEOPHYSICAL JOURNAL INTERNATIONAL,2017,210(3):1560-1569.

Han, Song,Zhang, Wei,&Zhang, Jie.(2017).Calculating qP-wave traveltimes in 2-D TTI media by high-order fast sweeping methods with a numerical quartic equation solver.GEOPHYSICAL JOURNAL INTERNATIONAL,210(3),1560-1569.

Han, Song,et al."Calculating qP-wave traveltimes in 2-D TTI media by high-order fast sweeping methods with a numerical quartic equation solver".GEOPHYSICAL JOURNAL INTERNATIONAL 210.3(2017):1560-1569.