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What Is the Principal Accuracy Limit of a Seismic Wavefields Simulated by a Finite-Difference Method?

Description: 

The finite-difference method is based on spatial discretization of a medium for which seismic wave propagation and earthquake motion are to be simulated. Moczo et al. (2022) systematically analyzed equations of motion in the wavenumber domain and found that the discrete (grid) representation of the heterogeneous medium must be wavenumber band-limited up to the Nyquist frequency. Mittet (2021a) reported that if the discrete grid model of medium coincides with the true medium up to some wavenumber, the simulated wavefield is accurate only up to a half of this wavenumber.

We present results of the comprehensive analysis focused on the principal limits of accuracy of numerically simulated wavefields. The analysis includes A. wavenumber spectra of a) exact wavefields in a heterogeneous elastic medium, b) wavenumber band-limited wavefields, c) spatially discretized wavefields, B. spatial dependence of the frequency spectrum of waves generated by a finite source, C. perturbing wavefields due to a small perturbation of the medium and due to a small wavenumber band-limited perturbation of the medium, D. interaction of an incoming wave with the medium perturbation through phase difference and wavenumber spectra.

In the synthesis of partial findings, we draw conclusions on the wavenumber limitation of wavefields in the wavenumber band-limited heterogeneous medium, and the principal consequence for the numerical modeling based on spatial discretization of the computational domain.

Session: Numerical Modeling in Seismology: Developments and Applications - I

Type: Oral

Date: 5/1/2024

Presentation Time: 08:30 AM (local time)

Presenting Author: Peter

Student Presenter: No

Invited Presentation: 

Authors