An Empirical Model for the Inter-Frequency Correlation of Epsilon for Fourier Amplitude Spectra

Date: 4/26/2019

Time: 06:00 PM

Room: Grand Ballroom

An empirical ground motion model (GMM) is presented for the inter-frequency correlation of normalized residuals, epsilon (ϵ), for smoothed Fourier amplitude spectra (FAS). The inter-frequency correlation of ϵ (ρ_ϵ) model is developed for the smoothed effective amplitude spectrum (EAS), as defined by PEER (Goulet et al., 2018). The EAS is the orientation-independent horizontal component FAS of ground acceleration. Ground-motion data are from the Pacific Earthquake Engineering Research Center (PEER) Next Generation Attenuation-West 2 (NGA-West2) database (Ancheta et al., 2014), which includes shallow crustal earthquakes in active tectonic regions. The normalized residuals are obtained from the Bayless and Abrahamson (2019) GMM, are partitioned into between-event, between-site, and within-site components, and a model is developed for the total correlation between frequencies. The total correlation model features a two-term exponential decay with the natural logarithm of frequency. At higher frequencies, the model differs substantially from previously published models, where the ground-motion smoothing technique employed has a large effect on the resulting correlations. The empirical ρ_ϵ are not found to have statistically significant magnitude, distance, site parameter, or regional dependence, although potential regional variations should be studied further. The model is applicable for crustal earthquakes in active tectonic regions worldwide, for rupture distances of 0 – 300 km, M 3.0 – 8.0, and over the frequency range 0.1 – 24 Hz.

Presenting Author: Jeff Bayless

Authors