Microtremor Horizontal-to-Vertical Spectral Ratio (mHVSR) Data Collection at Brentwood, 2022

Microtremor Horizontal-to-Vertical Spectral Ratios (mHVSR) are derived from ratios of the horizontal and vertical components of a Fourier Amplitude Spectra (FAS) from a 3-component recording of microtremors. This is done by recording ground vibrations either from a temporarily-deployed broadband seismometer, typically recording for a relatively short period of time (~1-2 hrs.), or from a permanently-installed broadband seismometer for a longer period of time. mHVSR can be very useful in identifying resonant frequencies where peaks in mHVSR represent resonance from impedance contrasts at a site. Many studies have found that the lowest resonant peak found in mHVSR is associated with the fundamental frequency of site. This study aims to perform mHVSR surveys at various sites in southern California to aid in the development of site response models by utilizing mHVSR to inform them and to also aid in the development of a large publicly accessible database for use in furthering research using mHVSR. This work will aid in a larger project associated with another DesignSafe doi (PRJ-4064). The database has been established and is available in the United States Community Shear-Wave Velocity (VS) Profile Database (PDB) (https://vspdb.org); the work presented in this doi is contributing to this database.