Implementation of NGA-West2 ground motion models in the 2014 U.S. National Seismic Hazard Maps

Earthquake Spectra
By: , and 



The U.S. National Seismic Hazard Maps (NSHMs) have been an important component of seismic design regulations in the United States for the past several decades. These maps present earthquake ground shaking intensities at specified probabilities of being exceeded over a 50-year time period. The previous version of the NSHMs was developed in 2008; during 2012 and 2013, scientists at the U.S. Geological Survey have been updating the maps based on their assessment of the “best available science,” resulting in the 2014 NSHMs. The update includes modifications to the seismic source models and the ground motion models (GMMs) for sites across the conterminous United States. This paper focuses on updates in the Western United States (WUS) due to the use of new GMMs for shallow crustal earthquakes in active tectonic regions developed by the Next Generation Attenuation (NGA-West2) project. Individual GMMs, their weighted combination, and their impact on the hazard maps relative to 2008 are discussed. In general, the combined effects of lower medians and increased standard deviations in the new GMMs have caused only small changes, within 5–20%, in the probabilistic ground motions for most sites across the WUS compared to the 2008 NSHMs.
Publication type Article
Publication Subtype Journal Article
Title Implementation of NGA-West2 ground motion models in the 2014 U.S. National Seismic Hazard Maps
Series title Earthquake Spectra
DOI 10.1193/062913EQS177M
Volume 30
Issue 3
Year Published 2014
Language English
Publisher Earthquake Engineering Research Institute
Contributing office(s) Geologic Hazards Science Center
Description 15 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Earthquake Spectra
First page 1319
Last page 1333
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