On evanescent wave field retrieval with the Marchenko method in 2D settings

TL;DR

This paper demonstrates that the Marchenko method can retrieve both propagating and evanescent waves in 2D settings, enhancing wavefield analysis without relying on traditional up-down decomposition.

Contribution

It introduces a new derivation of the Marchenko method capable of retrieving evanescent waves, expanding its applicability in wavefield reconstruction.

Findings

Evanescent waves can be retrieved using the Marchenko method in 2D.

Wave fields are visualized in the slowness-intercept-time domain.

Accurate initial focusing functions are crucial for wavefield coda retrieval.

Abstract

We show the capability of the Marchenko method to retrieve not only propagating waves, but also evanescent waves, based on a recent derivation of the Marchenko method that does not depend on up-down decomposition inside the medium of interest. We show how these wave fields can be easily retrieved in the slowness-intercept-time domain and what the wave fields look like when they are transformed back to the space-time domain. It is vital for the retrieval of the coda of the wave field that the initial estimate of the focusing function is a direct arrival that contains both the up-going and down-going component of the evanescent wave field. This is because these events directly overlay each other in time.