Extraction of multimode dispersion curves from ambient noise data in the North China craton

Surface-wave dispersion curves extracted by ambient noise cross correlation between two stations are widely used to image crust and upper mantle velocity structure in the last few years. In general, only fundamental-mode dispersion curves are used to invert shear wave velocity structure because higher-mode dispersion curves are difficult to be extracted. Recently, Wang and Chen presented a new method called vector wavenumber transformation method (VWTM) to extract higher-mode dispersion curves of surface waves. This new method can do a better job in extracting higher-mode dispersion curves for both small-scale engineering exploration and large-scale structure imaging of the crust and upper mantle. Here we apply this new method to extract multimode dispersion curves from continuous vertical component of ambient noise recorded by a temporary network in the North China craton. We test the influence of number of stations, station spacing, distribution of station on the extraction of higher-mode dispersion curves. Furthermore, we synthetize dispersion curves based on the velocity structure of this study area and compare those synthetic dispersion curves with those obtained by VWTM to verify the validity of this method. The extraction of higher-mode dispersion curves can be a better constraint for later inversion of high-resolution shear wave velocity structure of this area.