Poster #045, Ground Motions
Joint Calibration of NGA-East GMMs and Site Amplification Models Against CENA Ground Motions
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Poster Presentation
2021 SCEC Annual Meeting, Poster #045, SCEC Contribution #11551 VIEW PDF
yet.
Typically, in the development of GMMs, the core GMM (i.e., to predict the dependencies on magnitude and distance) and the site amplification model are developed iteratively and in a coordinated manner, as they are dependent on each other. This was not the case for the NGA-East project due to requirements in the GMM development associated with it having been a SSHAC Level 3 project (Budnitz et al. 1997).
We demonstrate that the combination of the NGA-East GMMs and CENA-specific site amplification factors leads to biased ground motions at short periods, whereas longer periods are relatively unbiased. We are in the process of expanding the NGA-East database using 333 events recorded since 2011. The new and original data will be used in mixed effects analysis, informed by new simulations of 1D ground response, to identify the primary sources of that bias (i.e., GMM or site amplification model) and provide the necessary adjustments to remove it. We expect that any modification to the GMM would be in its constant term, whereas modifications to the site amplification model would be made to a model component that predicts amplification of 760 m/s sites relative to 3000 m/s sites
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Typically, in the development of GMMs, the core GMM (i.e., to predict the dependencies on magnitude and distance) and the site amplification model are developed iteratively and in a coordinated manner, as they are dependent on each other. This was not the case for the NGA-East project due to requirements in the GMM development associated with it having been a SSHAC Level 3 project (Budnitz et al. 1997).
We demonstrate that the combination of the NGA-East GMMs and CENA-specific site amplification factors leads to biased ground motions at short periods, whereas longer periods are relatively unbiased. We are in the process of expanding the NGA-East database using 333 events recorded since 2011. The new and original data will be used in mixed effects analysis, informed by new simulations of 1D ground response, to identify the primary sources of that bias (i.e., GMM or site amplification model) and provide the necessary adjustments to remove it. We expect that any modification to the GMM would be in its constant term, whereas modifications to the site amplification model would be made to a model component that predicts amplification of 760 m/s sites relative to 3000 m/s sites
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