3D shear wave velocity structure delineation using ambient noise automatic analysis

Passive Seismic Interferometry (PSI) is considered as a revolutionary method characterized by a rapid development especially during the last decade. The method was initially based on the theory that the cross-correlation (CC) of random wave fields of ambient seismic noise recorded on two locations (stations) on the Earth’s surface yields an approximation of the Green’s function (GF) of the medium between the two locations. The retrieved empirical GF represents an approximation of the seismic response as if one of the two stations was acting as an impulsive source of surface waves (e.g. Claerbout, 1968; Lobkis and Weaver, 2001; Campillo and Paul, 2003; Shapiro and Campillo, 2004; Wapenaar, 2004; Cutris et al., 2006). Since the retrieved GF carries the signature of the velocity structure between the stations, the inter-station travel-times for surface- waves on multiple paths within a seismic network can be used in a tomographic inversion to image the seismic velocity perturbations, by performing the commonly called Ambient Noise Tomography (ANT).