Emergence of body waves from cross-correlation of short period seismic noise.

Abstract : Ambient noise correlation is now widely used in seismology to obtain the surface waves part of Green's function. More difficult is the extraction of body waves from noise correlations. Using 42 temporary broad-band three components stations located on the northern part of the fennoscandian region, we identify high-frequency (0.5-2 Hz) body waves emerging from noise correlations for inter-station distances up to 550 km. The comparison of the noise correlations with earthquake data confirms that the observed waves can be interpreted as P and S waves reflected from the Moho. Because the crustal model of the area is well known, we also compared the noise correlations with synthetic seismograms, and found an excellent agreement between the travel times of all the observed phases. Polarization analysis provides a further argument to confirm the observation of body waves.