Review of Recommendations for Probabilistic Seismic Hazard Analysis Guidance on Uncertainty and Use of Experts (1997) / Chapter Skim
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ESTIMATION OF EARTHQUAKE-GENERATED GROUND MOTION
ESTIMATION OF EARTHQUAKE-GENERATED GROUND MOTION
Pages 47-56
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From page 47... ...
Model predictions of EUS earthquake ground motion, whether empirical or theoretical, can vary significantly across the magnitude, distance, and frequency range of interest. SCIENTIFIC VALIDITY AND CLARITY OF PRESENTATION SSHAC's Chapter 5, together with the supporting Appendixes A and B (Ground Motion Workshops T and Il)
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From page 48... ...
It begins with basic ground motion measures; provides the fundamentals of magnitude, distance, and site response; and describes the essentials of empirical and theoretical predictions of earthquake ground motion. It explicitly warns against the use of fixed spectral shapes anchored by peak ground acceleration (PGA)
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From page 49... ...
Prior to the workshop, the four proponents were asked to provide estimates of peak acceleration and spectral accelerations based on the ground motion models they actually use, along with the corresponding estimates of epistem~c and aleatory uncertainties. The distances, frequencies, and magnitudes for which estimates were requested are listed in an unnumbered table in "Instructions for Proponents, " Appendix B
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From page 50... ...
The error bars represent + 6epis~emic range.
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From page 51... ...
The former are the preferred results, but the differences in median values and epistemic and aleatory uncertainties are slight. IMPLICATIONS FOR FIGURE GROUND MOTION ESTIMATION The many successes and few limitations of the Workshop IT elicitation/integration process are summarized in Section B.5, "Concluding Observations and Discussion," of the SSHAC report.
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From page 52... ...
to Experts 1 results (black) for 10-Hz spectral acceleration at mbLg = 5.5 as a function of distance.
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From page 53... ...
10-°4 03 FIGURE 5 . ic Experts 3 results, together with mean values and variances obtained from equally weighting the Experts 3 results for lO-Hz spectral acceleration at mb~g = 5.5 as a function of distance.
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From page 54... ...
values obtained using western North America strong-motion data, magnitudes." especially for large SSHAC did not comment on the extent to which the workshop ground motion estimates and uncertainties can actually be used in future PSHA studies, at any level. The pane!
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From page 55... ...
The broad agreement resulting from the two SSHAC ground motion workshops led to this opinion of the panel. With further consideration of some additional distances, frequencies, and magnitudes, together with appropriate interpolation schemes, ground motion matters of concern to PSHA could well be resolved at least for the next few years.
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