1887

Abstract

Summary

First-arrival traveltime tomography (FATT) is a seismic processing technique to obtain near-surface velocity structures using first-arrival traveltimes only. Although most classical FATT algorithms adopt ray-based method, many recent studies suggest using wave equation-based FATT because it resolves the disadvantages of ray-based tomography such as shadow zone problem. However, some wave equation-based FATT needs to calculate full wavefields in the frequency domain. Among them, we focus on a FATT algorithm based on damped wave equation. To obtain the frequency-domain wavefields, we can use the finite-difference method (FDM) or the finite-element method (FEM). We have been used the FEM to implement wave equation-based FATT for land seismic data with irregular topography. However, the FEM requires more computation-time than FDM does. In this study, we employ the embedded boundary method (EBM) to improve the efficiency of wave equation-based FATT algorithm. The EBM satisfies the free-surface boundary condition by adding virtual values to the grid points above the free-surface. Therefore, the FDM can describe irregular topography by using the EBM. Since the EBM based-FDM has higher computational efficiency, we can improve the computational efficiency of the FATT. The accuracy and computational efficiency of our algorithm are verified through the synthetic and field data examples.

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/content/papers/10.3997/2214-4609.201901527
2019-06-03
2020-04-05
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