Vector wave number transform method for extracting dispersion curves of multi-modes from ambient seismic noise

The spectrum of cross-correlation function of ambient seismic noise data recorded at two stations is widely recognized as proportional to the imaginary part of Green's function between these two stations. The cross-correlation should contain not only fundamental mode but also higher modes dispersion information of surface wave. Non-uniqueness occurs because only the fundamental mode dispersion information is used in the inversion. Therefor, extracting dispersion curves of higher modes and using them in the inversion is crucial for reducing non-uniqueness. In this paper, we propose a vector wavenumber transform method ( VWTM ) which can extract dispersion curves o f multi-modes from ambient seismic noise. We synthetise ambient noise data using generalizes reflection-transmission coefficient method and apply the VWTM to these synthetic noise data to assess the validity and applicability of VWTM. We discuss the influence of the distribution of the noise sources and the observation array and give the recommended observation array for different site situation. This study propose that the VWTM is a practical method for extracting the dispersion curves of multi-modes from ambient seismic noise data and has significant potential in the field of ambient seismic noise tomography.