Imaging Multimode Dispersion Curves of Rayleigh and Love Waves From Three-Component Noise Recordings in Urban Environments

With the advancements of three-component seismic instruments, much valuable information about source distributions and subsurface structures can be utilized to improve passive surface-wave imaging with anthropogenic seismic noise in urban environments. Current passive surface-wave methods, however, are mainly concerned with the Rayleigh waves in the vertical (Z) component, often neglecting the useful dispersion information in the radial (R) and transverse (T) components, particularly in higher modes of surface waves. So, we introduced the common-midpoint two-station analysis (CMP-TS) to extract the multimode dispersion curves of Rayleigh and Love waves from three-component noise recordings using multicomponent ambient seismic noise cross-correlations (ZZ, RR, and TT components). Results from synthetic data sets from given models show that the CMP-TS method is able to retrieve higher-mode Rayleigh waves from the RR component and improve the multimode dispersion measurements of Rayleigh waves by the summation of the ZZ and RR spectrograms. Besides, this method can extract multimode dispersion curves of Love waves with high resolution from the TT component. We applied the CMP-TS method to process three-component field data and retrieved the dispersion curves of Rayleigh waves with the fundamental and the first higher modes, as well as Love waves with the fundamental, the first, and second higher modes. The S-wave velocity model is constructed by inverting the fundamental and higher mode data and validated through borehole S-wave velocity measurements.