Implementation of NGA-West2 Ground Motion Models in the 2014 U.S. National Seismic Hazard Maps

2014 ◽  
Vol 30 (3) ◽  
pp. 1319-1333 ◽  
Author(s):  
Sanaz Rezaeian ◽  
Mark D. Petersen ◽  
Morgan P. Moschetti ◽  
Peter Powers ◽  
Stephen C. Harmsen ◽  
...  
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
Ground Motion ◽  
The United States ◽  
Hazard Maps ◽  
Seismic Hazard Maps ◽  
Motion Models ◽  
Seismic Source Models ◽  
Ground Motion Models ◽  
The U.S

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.

Ground Motion Models Used in the 2014 U.S. National Seismic Hazard Maps

2015 ◽  
Vol 31 (1_suppl) ◽  
pp. S59-S84 ◽  
Author(s):  
Sanaz Rezaeian ◽  
Mark D. Petersen ◽  
Morgan P. Moschetti
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
Ground Motion ◽  
The United States ◽  
Hazard Maps ◽  
Source Characterization ◽  
Ground Acceleration ◽  
Seismic Hazard Maps ◽  
Motion Models ◽  
Ground Motion Models

The National Seismic Hazard Maps (NSHMs) are an important component of seismic design regulations in the United States. This paper compares hazard using the new suite of ground motion models (GMMs) relative to hazard using the suite of GMMs applied in the previous version of the maps. The new source characterization models are used for both cases. A previous paper ( Rezaeian et al. 2014 ) discussed the five NGA-West2 GMMs used for shallow crustal earthquakes in the Western United States (WUS), which are also summarized here. Our focus in this paper is on GMMs for earthquakes in stable continental regions in the Central and Eastern United States (CEUS), as well as subduction interface and deep intraslab earthquakes. We consider building code hazard levels for peak ground acceleration (PGA), 0.2-s, and 1.0-s spectral accelerations (SAs) on uniform firm-rock site conditions. The GMM modifications in the updated version of the maps created changes in hazard within 5% to 20% in WUS; decreases within 5% to 20% in CEUS; changes within 5% to 15% for subduction interface earthquakes; and changes involving decreases of up to 50% and increases of up to 30% for deep intraslab earthquakes for most U.S. sites. These modifications were combined with changes resulting from modifications in the source characterization models to obtain the new hazard maps.

Documentation for the 2008 update of the United States National Seismic Hazard Maps

2008 ◽  
Author(s):  
Mark D. Petersen ◽  
Arthur D. Frankel ◽  
Stephen C. Harmsen ◽  
Charles S. Mueller ◽  
Kathleen M. Haller ◽  
...  
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
The United States ◽  
Hazard Maps ◽  
Seismic Hazard Maps

scholarly journals Seismic Hazard in the Nation's Breadbasket

2015 ◽  
Vol 31 (1_suppl) ◽  
pp. S109-S130 ◽  
Author(s):  
Oliver Boyd ◽  
Kathleen Haller ◽  
Nico Luco ◽  
Morgan Moschetti ◽  
Charles Mueller ◽  
...  
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Nearest Neighbor ◽  
Seismic Source ◽  
Eastern United States ◽  
Source Characterization ◽  
Nuclear Facilities ◽  
Motion Models ◽  
Ground Motion Models

The USGS National Seismic Hazard Maps were updated in 2014 and included several important changes for the central United States (CUS). Background seismicity sources were improved using a new moment-magnitude-based catalog; a new adaptive, nearest-neighbor smoothing kernel was implemented; and maximum magnitudes for background sources were updated. Areal source zones developed by the Central and Eastern United States Seismic Source Characterization for Nuclear Facilities project were simplified and adopted. The weighting scheme for ground motion models was updated, giving more weight to models with a faster attenuation with distance compared to the previous maps. Overall, hazard changes (2% probability of exceedance in 50 years, across a range of ground-motion frequencies) were smaller than 10% in most of the CUS relative to the 2008 USGS maps despite new ground motion models and their assigned logic tree weights that reduced the probabilistic ground motions by 5–20%.

USGS National Seismic Hazard Maps

2000 ◽  
Vol 16 (1) ◽  
pp. 1-19 ◽  
Author(s):  
A. D. Frankel ◽  
C. S. Mueller ◽  
T. P. Barnhard ◽  
E. V. Leyendecker ◽  
R. L. Wesson ◽  
...  
Keyword(s):  
United States ◽  
South Carolina ◽  
Seismic Hazard ◽  
Spectral Response ◽  
The United States ◽  
Great Earthquake ◽  
Hazard Maps ◽  
Seismic Hazard Maps ◽  
Large Earthquakes ◽  
Historic Seismicity

The U.S. Geological Survey (USGS) recently completed new probabilistic seismic hazard maps for the United States, including Alaska and Hawaii. These hazard maps form the basis of the probabilistic component of the design maps used in the 1997 edition of the NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structures, prepared by the Building Seismic Safety Council and published by FEMA. The hazard maps depict peak horizontal ground acceleration and spectral response at 0.2, 0.3, and 1.0 sec periods, with 10%, 5%, and 2% probabilities of exceedance in 50 years, corresponding to return times of about 500, 1000, and 2500 years, respectively. In this paper we outline the methodology used to construct the hazard maps. There are three basic components to the maps. First, we use spatially smoothed historic seismicity as one portion of the hazard calculation. In this model, we apply the general observation that moderate and large earthquakes tend to occur near areas of previous small or moderate events, with some notable exceptions. Second, we consider large background source zones based on broad geologic criteria to quantify hazard in areas with little or no historic seismicity, but with the potential for generating large events. Third, we include the hazard from specific fault sources. We use about 450 faults in the western United States (WUS) and derive recurrence times from either geologic slip rates or the dating of pre-historic earthquakes from trenching of faults or other paleoseismic methods. Recurrence estimates for large earthquakes in New Madrid and Charleston, South Carolina, were taken from recent paleoliquefaction studies. We used logic trees to incorporate different seismicity models, fault recurrence models, Cascadia great earthquake scenarios, and ground-motion attenuation relations. We present disaggregation plots showing the contribution to hazard at four cities from potential earthquakes with various magnitudes and distances.

scholarly journals Documentation for the 2014 update of the United States national seismic hazard maps

2014 ◽  
Author(s):  
Mark D. Petersen ◽  
Morgan P. Moschetti ◽  
Peter M. Powers ◽  
Charles S. Mueller ◽  
Kathleen M. Haller ◽  
...  
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
The United States ◽  
Hazard Maps ◽  
Seismic Hazard Maps

Seismic Hazard in the Eastern United States

2015 ◽  
Vol 31 (1_suppl) ◽  
pp. S85-S107 ◽  
Author(s):  
Charles S. Mueller ◽  
Oliver S. Boyd ◽  
Mark D. Petersen ◽  
Morgan P. Moschetti ◽  
Sanaz Rezaeian ◽  
...  
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
New England ◽  
Ground Motion ◽  
Maximum Magnitude ◽  
Eastern United States ◽  
Adaptive Smoothing ◽  
Motion Models ◽  
Background Seismicity ◽  
Ground Motion Models

The U.S. Geological Survey seismic hazard maps for the central and eastern United States were updated in 2014. We analyze results and changes for the eastern part of the region. Ratio maps are presented, along with tables of ground motions and deaggregations for selected cities. The Charleston fault model was revised, and a new fault source for Charlevoix was added. Background seismicity sources utilized an updated catalog, revised completeness and recurrence models, and a new adaptive smoothing procedure. Maximum-magnitude models and ground motion models were also updated. Broad, regional hazard reductions of 5%–20% are mostly attributed to new ground motion models with stronger near-source attenuation. The revised Charleston fault geometry redistributes local hazard, and the new Charlevoix source increases hazard in northern New England. Strong increases in mid- to high-frequency hazard at some locations—for example, southern New Hampshire, central Virginia, and eastern Tennessee—are attributed to updated catalogs and/or smoothing.

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