The Marchenko method for evanescent waves

TL;DR

This paper explores extending the Marchenko method to include evanescent waves, enabling better subsurface imaging by retrieving both downward and upward decaying wave components, despite some sensitivity issues.

Contribution

It presents a first step towards adapting the Marchenko method for evanescent waves, analyzing its capabilities and limitations for the first time.

Findings

Downward decaying components can be retrieved accurately.

Upward decaying components are highly sensitive to model errors.

Potential development of methods for refracted waves in wide-angle data.

Abstract

With the Marchenko method, Green's functions in the subsurface can be retrieved from seismic reflection data at the surface. State-of-the-art Marchenko methods work well for propagating waves but break down for evanescent waves. This paper discusses a first step towards extending the Marchenko method for evanescent waves and analyses its possibilities and limitations. In theory both the downward and upward decaying components can be retrieved. The retrieval of the upward decaying component appears to be very sensitive to model errors, but the downward decaying component, including multiple reflections, can be retrieved in a reasonably stable and accurate way. The reported research opens the way to develop new Marchenko methods that can handle refracted waves in wide-angle reflection data.