Near-surface shear-wave velocities and quality factors derived from high-frequency surface waves

Shear (S)-wave velocities of near-surface materials can be derived from inverting the dispersive phase velocity of high-frequency (≥ 2 Hz) surface (Rayleigh and/or Love) waves (e.g., Song et al., 1989). Multichannel analysis of surface waves (MASW) uses phase information of high-frequency Rayleigh waves recorded on vertical component geophones to determine S-wave velocities (Miller et al., 1999). Multichannel analysis of Love waves (MALW) uses phase information of high-frequency Love waves recorded on horizontal (perpendicular to the direction of wave propagation) component geophones to determine S-wave velocities (Xia, 2012b). Both MASW and MALW possess stable and efficient inversion algorithms to invert phase velocities of surface waves but MALW has some attractive advantages: (1) Love-wave dispersion curves are simpler than those of Rayleigh waves; (2) dispersion images of Love-wave energy have a higher signal-to-noise ratio and are more focused than those generated from Rayleigh waves; and (3) inversion of Love-wave dispersion curves is less dependent on initial models and more stable than from Rayleigh waves.