<math>Q</math> and high-frequency strong motion spectra: Fid-Bau Portal

$Q$ and high-frequency strong motion spectra

Trifunac, M.D.

Abstract Empirical scaling equations for Fourier amplitude spectra of strong ground motion are used to describe $A 0$ and τ in the assumed (high-frequency) shape of strong motion amplitudes: $FS(φ) = A 0 e-$ ^πτφ. The res of computed $A 0$ and τ with other related estimates of spectral amplitudes; (2) smooth decay of strong motion spectral amplitudes up to $φ = 25 Hz$ , without an abrupt low-pass filtering of high frequecies; and (3) good agreement with other estimates of the regionally specific attenuation of high-frequncy seismic waves. As the recorded strong earthquake shaking in the western United States typically samples only the shallow (10 km) and local (100km) characteristics of wave attenuation, the processed strong motion accelerograms can be used as the most direct means of describing the nature of the high-frequency attenuation of the entire strong motion signal for use in earthquake engineering applications. Seismological body wave, Lg and coda wave estimates of $Q$ sample different volumes of the crust surrounding the station, and involve different paths of the waves. These differences must be carefully documented and understood before the results can be used in earthquake engineering characterization of strong motion amplitudes.