Underestimation of body waves and feasibility of surface-wave reconstruction by seismic interferometry

Interferometry is an approach to extract the Green's function between two receivers as if the virtual source is at one of the receiver locations. The Green's function which is the response to an impulsive source, accounts for the wave propagation in the medium between the two receivers. It is commonly thought that Green's function estimates obtained from interferometry accurately represent the full Green's function, but this is not always the case. In fact, the accuracy of the retrieved Green's function, which consists of the surface and body waves, is in practice restricted by the limited distribution of the sources of field fluctuations. We demonstrate the importance of adequate source distribution for the accuracy of the retrieved Green's function, using examples from interferometry applications. In these examples, sources are controlled (as in exploration seismology) or uncontrolled (as in crustal seismology).