Moho-reflected shear wave from seismic noise correlations in southern Korea

The Green’s function between two seismic stations can be retrieved from the cross-correlation operation of ambient noise recordings (Wapenaar, 2004). Many studies have successfully applied this technique to the surface wave propagation in long period band. However, the case applied to body wave propagation is rarely addressed. Zhan et al., (2010) explains the reason causing the difficulty in retrieving body wave phases and describes comparable amount of body wave energy can be visible under certain conditions. In southern Korea, Kang and Shin (2006) and Choi (2009) extracted Rayleigh wave energy by cross-correlation of ambient noise and investigated crustal velocity structure less than 8 km depth. In this study, we are to show Moho-reflected body wave (SmS) energy can be retrieved from the broadband vertical velocity recordings and try to build shear wave velocity distribution. We took seismograms continuously recorded during January 2007 at 19 broadband stations in southern Korea. As an example, the correlation pairs with MGB station located in central area of southern Korea generally exhibit surface wave energy of which group velocity is around 3.0 km/s and weak energy of higher velocity seems to correspond to body wave. Correlation of longer duration of noise signals and spectral whitening is helpful to enhance body wave signal.