Near field influence on Green´s function retrieval in seismic interferometry (wave equation case)

The virtual source method is used to reduce responses of conventional seismic experiment to the needed for observation horizon. Normally such speculations are based on approximation of the exact integral representation for an imaginary (or real) part of Green´s function in high frequency regime and far field. We emphasize that high frequency approach already contains an error due to sources-receivers closeness and acts as the far field approach at the same time. In this paper the accuracy of the standard approach is examined.