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Expert panel recommendations for ergodic site amplification in Central and Eastern North America

Stewart, Jonathan P.; Parker, Grace A.; Harmon, Joseph A.; Atkinson, Gail M.; Boore, David M.; Darragh, Robert B.; Silva, Walter J.; Hashash, Youssef M. A.

PEER-2017/04, Pacific Earthquake Engineering Research (PEER) Center, University of California, Berkeley, Authors and publishers retain copyright, 2017-03, PDF

The U.S. Geological Survey (USGS) national seismic hazard maps have historically been produced for a reference site condition of V_S30 = 760 m/sec (where V_S30 is time averaged shear wave velocity in the upper 30 m of the site). The resulting ground motions are modified for five site classes (A-E) using site amplification factors for peak acceleration and ranges of short- and long-oscillator periods. As a result of Project 17 recommendations, this practice is being revised: (1) maps will be produced for a range of site conditions (as represented by V_S30) instead of a single reference condition; and (2) the use of site factors for period ranges is being replaced with period-specific factors over the period range of interest (approximately 0.1 to 10 sec). This project and a large amount of previous and contemporaneous related research (e.g., NGA-East Geotechnical Working Group for site response) has sought to provide an improved basis for the evaluation of ergodic site amplification in central and eastern North America (CENA). The specific scope of this project was to review and synthesize relevant research results so as to provide recommendations to the USGS for the modeling of ergodic site amplification in CENA for application in the next version of USGS maps. The models provided in this report are recommended for application by the USGS and other entities. An electronic supplement to PEER Report 2017-04 can found on PEER Reports page under the report title: PEER Reports 2017 .

Available online: https://peer.berkeley.edu/sites/default/files/jonathan-p-stewart-grace-a-parker-2017_04.pdf