Direct Waveform Inversion by Iterative Inverse Propagation

TL;DR

This paper introduces a new deterministic iterative method for full waveform seismic inversion that directly relates Earth structure to recorded seismograms through a non-linear integral equation, improving resolution over traditional techniques.

Contribution

It develops a novel inverse scattering approach for full waveform inversion that avoids linearization and statistical searches, providing a deterministic solution based on a non-linear integral equation.

Findings

Numerical results in 1D demonstrate the method's effectiveness.

The approach does not require a misfit function or random searches.

The algorithm is computationally intensive but yields high-resolution images.

Abstract

Seismic waves are the most sensitive probe of the Earth's interior we have. With the dense data sets available in exploration, images of subsurface structures can be obtained through processes such as migration. Unfortunately, relating these surface recordings to actual Earth properties is non-trivial. Tomographic techniques use only a small amount of the information contained in the full seismogram and result in relatively low resolution images. Other methods use a larger amount of the seismogram but are based on either linearization of the problem, an expensive statistical search over a limited range of models, or both. We present the development of a new approach to full waveform inversion, i.e., inversion which uses the complete seismogram. This new method, which falls under the general category of inverse scattering, is based on a highly non-linear Fredholm integral equation relating the Earth structure to itself and to the recorded seismograms. An iterative solution to this equation is proposed. The resulting algorithm is numerically intensive but is deterministic, i.e., random searches of model space are not required and no misfit function is needed. Impressive numerical results in 1D are shown for several test cases.