Technical Updates: 2015, Second Quarter


    The NGA-East project has completed most of its technical tasks this quarter. The technical integration (TI) team continued their weekly web meetings to interact and make decisions regarding the evaluation and integration tasks. In addition, the TI team invited the Participatory Peer Review Panel (PPRP) and the Joint Management Committee (JMC) to a Working Meeting on April 13, 2015. A summary of progress following the March 4-5 SSHAC Workshop was presented and discussed at that time.

    The last SSHAC Workshop (SSHAC theme 3) was hosted at the Faculty Club in Berkeley on June 17 and 18. The TI team presented its proponent GMC model and the meeting was rich in interactions among the participants. This issue of the Technical Updates summarizes progress of the model building process, Project Plan tasks H, J, K, and L (see below). Progress on additional complementary tasks were also presented and discussed at the workshop, along with hazard sensitivity results (task M), when applicable. Unless otherwise specified, presentations linked below are from the June 17-18 SSHAC Workshop. All the presentations for this SSHAC workshop are available here. The Workshop presentations often reflect results from collective work from many participants over extended periods of time. The co-authors listed on the title slides only represent those who prepared the specific presentations.

Development of Median Ground Motion Prediction Equations (Task H)

    • All the ground-motion models (GMMs) were re-evaluated and re-modeled (as needed) to very close and very large distances (within 10 km and up to 1500 km, slides here).
    • Two independent Gulf Coast adjustment models were developed (slides here) and documented for inclusion in a new PEER report on median GMM adjustments. A third model to address Gulf Coast site effects is being documented.
    • Various tasks were completed on the issue of source depth, including data investigation and sensitivity analyses (slides here) as well as the the development of a source-depth model to be applied as an adjustment to median GMMs (slides here). This is also being included in the median GMM adjustment report currently under preparation.
    • The proposed approach to address hanging-wall effects was also summarized (slides here).

Sigma (Standard Deviation) (Task J) and Evaluation of Epistemic Uncertainty (Task K)

    • The progress on the Sigma tasks are summarized in this presentation. Key items include the refinement and development of final sigma models (Task J). The presentation also includes the evaluation and integration of the models (weight assignment and logic tree definition), which is part of Task H.
    • The final candidate sigma models are documented in PEER Report 2015/07, which was published in June.

Evaluation of Epistemic Uncertainty (Task K)

    An updated flowchart was presented that better illustrate the process selected by the TI team for quantifying the epistemic uncertainty in median ground motions (flowchart here and slides here). The following tasks were summarized at the workshop:

    • Evaluation of candidate median GMMs (slides here).
    • Development of a continuous distribution of median GMMs (slides here).
    • Visualization of the ground-motion space and re-discretization (slides here).
    • Weight assignment for selected median GMMs (slides here).


    The following PEER reports were published in the NGA-East series. All the reports are available here:

    • Report 2015/04: NGA-East: Median Ground-Motion Models for the Central and Eastern North America Region (published in April)
    • Report 2015/06: Adjusting Ground-Motion Intensity Measures to a Reference Site for which VS30 = 3000 m/sec (published in May)
    • Report 2015/07: NGA-East: Ground-Motion Standard Deviation Models for Central and Eastern North America (published in June).

    A new PEER report is being drafted to address median GMM adjustments (for distance extrapolation, source depth effects and Gulf Coast region).

Presentations at Conferences

    Numerous oral and poster presentations were made on NGA-East topics at the SSA annual meeting in Pasadena (April 21-23) and at the AGC/CGU Joint Assembly in Montreal (May 3-7).

  • Presentations at the SSA meeting included:
    • “Application of Broadband Simulation Technique in Development of New Hybrid Empirical Ground Motion Model in Central and Eastern North America” (abstract here), by Shahjouei, A. and Pezeshk, S.
    • “Development of GMPEs with Multiple Region-Specific Random Effects: the PEER NGA-East Example” (abstract here), by Goulet, N. M., Hollenback, J., Goulet, C. and Abrahamson, N.
    • “Empirical Ground Motion Prediction Equations for Eastern North America with the Addition of Intensity Observation” (abstract here), by Al Noman, M. N. and Cramer, C. H.
    • “Ground Motion Prediction Equations for Eastern North America Using a Hybrid Empirical Method” (abstract here), by Pezeshk, S., Zandieh, A., Campbell, K. W., and Tavakoli, B.
    • “Response Spectra Ground-Motion Prediction Equation Development Based on Empirical Fourier Amplitude Spectra Model and Calibrated Duration Model: the PEER NGA-East Example” (abstract here), by Hollenback, J. C., Goulet, N., Goulet, C., and Abrahamson, N. A.
    • “SCEC Broadband Platform Simulations for the PEER NGA-East Project” (abstract here), by Bayless, J. R., Goulet, C. A. and Hollenback, J.


  • Presentations at the AGC/CGU Joint Assembly included (all abstracts here):
    • “NGA-East Database”, by Kishida, T. Goulet, C. A., Ancheta, T. D., Cramer, C. H., Darragh, R. B., Silva, W. J., Hashash, Y. M. A., Harmon, J., Stewart, J. P. Wooddell, K. E. and Youngs, R. R.
    • “A Hybrid Empirical Ground Motion Prediction Model for Eastern North America”, by Pezeshk, S., Zandieh, A., Campbell, K. W., and Tavakoli, B.
    • “Regionally-Adjustable Generic Ground-Motion Prediction Equation:
      Application to Central and Eastern North America”, by E. Yenier and G. Atkinson
    • “An ENA Empirical GMPE based on the NGA East Database and Intensity Observations”, by Cramer, C. H., Al Noman, N. M. and Ogweno, P.
    • “PEER NGA-East Overview: Development of a Ground Motion Characterization Model and Ground Motion Prediction Equations for Central and Eastern North America”, by Goulet, C. A., Bozorgnia, Y. and Abrahamson, N. A.
    • “Ground-Motion Prediction Equation Development Using Random Vibration Theory, Bayesian Regression, and Finite Fault Simulations: The PEER NGA-East Example”, by Hollenback, J. C., Kuehn, N. M., A. Goulet, C. A. and Abrahamson, N. A.