Project Abstract
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There is increasing recognition that simulations can be utilized in engineering applications, but the simulations require application-specific validation first. In this SCEC study, we evaluate the inter-frequency correlation of Fourier amplitude spectra (FAS) residuals from CyberShake v15.4 simulations, including comparisons with an empirical model.
We collect a database of CyberShake simulations, process the ground motions, perform a residual analysis, and evaluate the inter-frequency correlation of the residuals. Two accomplishments are made towards a broader CyberShake validation. One, we facilitate future validations of inter-frequency correlation by providing a repeatable framework. Second, we find that between 0.1-0.5 Hz the simulations have a satisfactory level of total inter-frequency correlation, which is a significant improvement from the conclusions of Bayless and Abrahamson (2018) about the SCEC BBP simulations.
We observe that the between-site component of the residuals has correlation which is significantly higher than the empirical model at frequencies below 0.5 Hz, but is lower at frequencies above 0.5 Hz. This discrepancy may be due to the smoothness of the seismic velocity model in the near surface, or it may be related to the effects of low frequency basin waves mapped into the site terms.
In a future study, we hope to investigate the between-site component of the residuals (by evaluating the effect of low frequency basin waves, or by utilizing results from alternative velocity models, or by investigating repeatable path effects). Additionally, we would like to repeat our analysis with higher fmax CyberShake simulations (e.g. v15.12) and other regions (e.g. v17.3, v18.8). |
