Estimation of Bedrock Depth Using the Horizontal-to-vertical (H/V) Ambient-noise Seismic Method

Estimation of shear (S)-wave velocities by inversion of high frequency ( 2 Hz) Rayleigh waves has been given increasingly more attention by the near-surface geophysical community with application to a variety of near-surface geological and geophysical problems. For a given near-surface geophysical problem, it is essential to understand how well the data, calculated according to a layered-earth model, might match the observed data. It is also important to recognize that a match may only be possible for data within a certain frequency range or at specific frequencies because the sensitivity of Rayleigh-wave phase velocities due to changes in S-wave velocities varies with frequency. To provide insights into the process of inverting Rayleigh-wave phase velocities to estimate S-wave velocity structure, we introduced and discussed a data resolution matrix and a model resolution matrix of a damped least-square method. The resulting discussion indicated that each near-surface geophysical target can only be resolved using Rayleigh-wave phase velocities within specific frequency ranges and higher mode data are normally more accurately predicted than fundamental mode data because of restrictions on the data kernel of the inversion system. We proposed an inversion of data selected according to the data resolution matrix. The synthetic and real-world examples demonstrated that the proposed inversion could produce models with higher data resolution as well as higher model resolution.