Contributors: Jack Baker, James Bronder, Abhineet Gupta, Yue Hua, Nirmal Jayaram, David Lallemant, Ting Lin, Christophe Loth, Lynne Burks, Yoshifumi Yamamoto
Some of the research presented on this web site relies on ground motion prediction equations (Gapes) to estimate 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).
Users desiring additional information, or looking for other GMPEs, are referred to John Douglas's excellent compilation at this site.
Note: Note these models were formerly referred to as "attenuation models," but the use of that name is being discouraged as it is misleading in what exactly these models provide. An explanation for this change is provided here. Users of these models should refer to them as "ground motion prediction equations" or "ground motion models" rather than "attenuation models."
NGA models: these models were developed as part of the PEER Next Generation Attenuation project
1997 Seismological Research Letters models: these models were published in Seismological Research Letters, 1997, Vol 68, Issue 1.
Spectral acceleration predictions for other regions
Prediction models for other intensity measures
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.
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You are welcome to download and use any of these materials, as long as you acknowledge this web site and associated publications as the source of the data. The Matlab scripts are free software; you can redistribute them and/or modify them under the terms of the GNU General Public License as published by the Free Software Foundation, version 2. This software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.