Vs-0 Correction Factors for Input Ground Motions used in Seismic Site Response Analyses

Input motions used in seismic site response analyses are commonly selected based on similarities between the shear wave velocity (Vs) at the recording station, and the reference depth at the site of interest (among other aspects such as the intensity of the expected ground motion). This traditional approach disregards the influence of the attenuation in the shallow crust on site response. Given that this attenuation (damping) can be characterized by the distance-independent high-frequency attenuation parameter 0, a Vs-0 correction framework for input motions is proposed to render them compatible with the assumed properties of the reference depth at the site. The proposed correction factors were applied to a subset of recordings from the KiK-net database, and compared to traditional deconvolution. Results indicate that Vs-0 corrected motions outperform deconvolved motions in the characterization of the spectral energy in the high-frequency range. However, motions recorded at sites with soft deposits are not good candidates for the Vs-0 correction approach. Vs-0 corrections also affect amplification functions which are important in the assessment of site-specific seismic hazards.