UCLA

Frequency-dependent horizontal-to-vertical spectral ratios (HVSR) of three-component recordings provide information on-site resonant frequencies, which are potentially useful for predicting site response. We compute microtremor-derived HVSR (mHVSR) from Fourier amplitude spectra (FAS) using a relational database for site data, mainly in California. Using these data, we identify sites with peaks, sites with no peaks, and characteristics of peaks for sites that have them. Using a separate relational database for earthquake ground motion studies, we identify period-dependent response-spectra site terms, which reflect the mean offsets of site-specific ground motions from predictions of a ground motion model (GMM). Those site terms may have peaks, no peaks, or transitions from low-to-high values (with or without peaks) over some period range. This paper evaluates the degree to which features of site terms can be mapped to features of mHVSR at the same site. This is an important step towards the eventual development of an mHVSR-conditioned site response model to capture such features.