Development of shear-wave velocity profiles and kappa compatible with Ground Motion model for Taiwan

Abstract

A new velocity model (GMM) compatible with a ground motion prediction model (GMM) for Taiwan is presented in this study. The model is developed using the data set extracted from the flatfile compiled for Taiwan Senior Seismic Hazard Analysis Committee (SSHAC) level 3 project (NCREE, 2015). The Phung et al. (2020) ergodic Sa GMM was used as a backbone model for estimating the site amplification in the frequency domain using inverse Random vibration theory (IRVT). The main motivation for developing a velocity model is that the estimation of the site scaling in terms of the time-averaged shear-wave velocity over the top 30 m (VS30), the method also provides the corresponding depth-dependent VS(z) profiles and the value for the selected VS30 value as a result of the inverse quarter-wave-length method (IQWL). Not all of the empirical amplification can be explained by the 1-D VS profiles andvalues. For soft sites (VS30 < 500 m/s), and intermediate periods (0.5-2.0 sec), there is additional amplification in the empirical data which is attributed to 3-D path and site effects. Using the proposed method, the resulting GMM provides a VS profile, k, and 3-D effect for each VS30 value, which provides a more informative handoff of ground-motion information for use in site-specific site response studies.