An Empirical Model for Fourier Amplitude Spectra using the NGA-West2 Database, PEER Report 2018-07


An empirical ground-motion model (GMM) for shallow crustal earthquakes in California and Nevada based on the NGA-West2 database [Ancheta et al. 2014] is presented. Rather than the traditional response spectrum GMM, this 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 Fourier amplitude spectrum (FAS) of ground acceleration. The model is developed using a database dominated by California earthquakes, but takes advantage of crustal earthquake data worldwide to constrain the magnitude scaling and geometric spreading. The near-fault saturation is guided by finite-fault numerical simulations and non-linear site amplification is incorporated using a modified version of Hashash et al. [2018]. The model is applicable for rupture distances of 0–300 km, M 3.0 – 8.0, and over the frequency range 0.1–100 Hz. The model is considered applicable for Vs30 in the range 180–1500 m/sec, although it is not well constrained for Vs30 values greater than 1000 m/sec. Models for the median and the aleatory variability of the EAS are developed. Regional models for Japan and Taiwan will be developed in a future update of the model. A MATLAB program that implements the EAS GMM is provided as an electronic appendix.

- Electronic Appendix A (38 MB)
- Electronic Appendix B (52 KB)

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Jeff Bayless
Norman A. Abrahamson
Publication date: 
December 2, 2018
Publication type: 
Technical Report
Bayless, J., & Abrahamson, N.A. (2018). An Empirical Model for Fourier Amplitude Spectra using the NGA-West2 Database, PEER Report 2018-07. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA.