Abstract Train traffic represents a powerful but underutilized seismic source for near-surface geophysics. We propose a method that exploits this source to extract guided P waves, which complement surface wave normal modes, for constraining P wave velocity structure. Using seismic interferometry by cross-coherence on stationary-phase train seismic data segments, we retrieve multimodal Rayleigh and guided P waves. Their dispersion curves are then jointly inverted for P and S wave velocity profiles via a determinant misfit function. The effectiveness of this approach is validated by synthetic data tests. From field train seismic data, we extract strong guided P waves in a frequency band of 18 to 30 Hz. P and S wave velocity structures down to a depth of 50 m are simultaneously determined from guided P wave and multimodal Rayleigh wave dispersion data. The results demonstrate that guided P waves can be extracted from train-generated vibrations and inverted for determining shallow P-wave velocities, which bring a novel approach for near-surface P wave velocity estimation using a train traffic seismic source.
Mi et al. (Wed,) studied this question.