Single-Station Six-Component Horizontal-to-Vertical Spectral Ratio Method for Subsurface Structure Inversion

In seismic exploration, subsurface structures are commonly investigated using dense sensor arrays. While effective, array-based observations require a large number of sensors, resulting in complex field deployment. Single-station seismic methods offer an attractive alternative by leveraging constraints among different seismic components at a single site. Nevertheless, existing single-station seismic methods do not fully utilize the complete six-component information provided by seismometers, and the extraction of dispersion curves is affected by instrument response, which limits the accuracy of single-station methods.

 

To overcome these limitations, we propose a single-station six-component Horizontal-to-Vertical Spectral Ratio method (6-C HVSR). This method considers both translational HVSR and rotational HVSR, enabling it to eliminate curve distortion caused by instrument response. The proposed 6-C HVSR forward model can be directly constructed using existing surface-wave forward modeling frameworks, enabling subsurface structure inversion without introducing additional assumptions. Unlike traditional HVSR methods, the 6-C HVSR applicable to subsurface structure inversion has a clearer physical meaning.

 

By integrating both translational and rotational HVSR, the proposed method fully utilizes all six-component data and improves constraints on subsurface structures under single-station conditions. Moreover, it reduces requirements for measurement instruments and enables further improvements in measurement accuracy. Borehole comparison experiments demonstrate that the method can estimate subsurface structures using single-station observations.