Incorporating array processing to improve resolution of ambient noise data cross‐correlation along a horizontal array.

Numerous authors have shown that the cross‐correlation of ambient noise recordings at two points can produce an approximation of the Green’s function between those points. The resolution of the cross‐correlation is fundamentally limited by the characteristics of the noise field and the changing environment. In order to make this technique the most effective, we wish to limit the time needed to extract the desired environmental information. To that end, array processing techniques can be adapted to work with the noise cross‐correlation function taken along a horizontal array to decrease the time needed to resolve multiple individual returns. For a given noise field, beam forming between horizontal arrays is effective in reducing the time needed to identify both the direct and single‐bounce surface reflection paths.