Estimating frequency-dependent shear wave velocity in near-surface sediment based on seismic interferometry

Near-surface seismic shear wave is a basic tool for seismic investigations. However, its frequency-dependent property is not fully investigated, especially by the in-situ observation method. Here, we develop the seismic interferometry with a moving frequency window to process the natural seismic signals recorded by the KiK-net network. It is observed that the phase velocity of the shear wave decreases sharply as the frequency increases in the low-frequency range, and remains constant in the high-frequency range. The observed dispersion phenomenon presents a challenge to existing site effect prediction theories, while also providing an observational reference for understanding how the shear wave propagates in near-surface sediment.