Ground Motion Prediction Model Scripts

by Jack Baker, Nirmal Jayaram, Ting Lin and Yoshifumi Yamamoto, November 2008

Some of the research presented on this web site relies on ground motion prediction ("attenuation") models to estimate the probability distributions of observed ground motion intensity associated with a given earthquake magnitude, source-to-site distance, etc. As a courtesy, Matlab scripts are provided here for a variety of popular models published in the scientific literature. You are welcome to use these scripts as long as you acknowledge this web site as their source (and of course cite the original model publications).

The following models for spectral acceleration (Sa) were published in Volume 68, Issue 1 of Seismological Research Letters, in 1997.

• Abrahamson and Silva, horizontal Sa
• Boore et al., horizontal Sa
• Campbell, horizontal Sa
• Sadigh et al, horizontal Sa
• Abrahamson and Silva, vertical Sa
• Campbell, vertical Sa

The following models were developed as part of the PEER Next Generation Attenuation project, as documented in the 2008 Earthquake Spectra NGA Special Issue.

• Boore and Atkinson (sigma for average component only)
• Campbell and Bozorgnia (sigma for average or arbitrary component)
• Chiou and Youngs (sigma for average component only)

Correlations between spectral acceleration values are also required for some of the calculations in the research presented here. The following script provides a calculation of predicted correlations between spectral acceleration values at two periods, as documented in the same NGA special issue.

• Baker and Jayaram model for correlations of Sa values, from Baker J.W. and Jayaram N., 2008. Correlation of spectral acceleration values from NGA ground motion models, Earthquake Spectra, 24 (1), 299-317.

Note: there is a potential for ambiguity in the definition of "horizontal spectral acceleration," and the precise definition has some impact on the predicted probability distribution. More explanation is provided here and here. The 1997 models generally provided the distribution of the geometric mean of spectral acceleration from two horizontal ground motion components. The new NGA models are more explicit as to which definition they use.