For designing buildings and other structures to safely resist earthquakes, the 2009 NEHRP Recommended Seismic Provisions and the 2010 ASCE/SEI 7 Standard contain maps of Uniform Hazard response accelerations, risk coefficients, 84th-percentile spectral accelerations, and Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations, all at spectral periods of 0.2-second and 1.0-second. The spectral accelerations are for the direction of maximum horizontal response and a site shear wave velocity (VS30) of 760 m/s, in units of the percent g, the acceleration of gravity. For more information, see Chapters 11, 21, and 22 of the 2009 NEHRP Recommended Seismic Provisions and the 2010 ASCE/SEI 7 Standard.

The Maximum Considered Earthquake Geometric Mean (MCEG) peak ground acceleration (PGA) values of the 2009 NEHRP Recommended Seismic Provisions and the 2010 ASCE/SEI 7 Standard are calculated from the data in the downloadable files below, via the following equations: PGA = min[ PGAUH , max( PGAD84th , 0.6 ) ] for the 2009 NEHRP Recommended Seismic Provisions; PGA = min[ PGAUH , max( PGAD84th , 0.5 ) ] for the 2010 ASCE/SEI 7 Standard; where PGAUH = uniform-hazard peak ground acceleration; PGAD84th = 84th-percentile peak ground acceleration. These peak ground accelerations are each for the geometric mean of two horizontal components and a site shear wave velocity (VS30) of 760 m/s. For more information, see Chapters 11, 21, and 22 of the 2009 NEHRP Recommended Seismic Provisions and the 2010 ASCE/SEI 7 Standard. Note: The USGS Seismic Design Web Services first spatially interpolate the uniform-hazard (PGAUH) and 84th-percentile (PGAD84th) gridded values, and then combine the interpolated values via the equation above. If instead one first combines the gridded values (via the equation above) and then spatially interpolates, the resulting values will not necessarily be equal to those from the web services. For deterministic values, the lower limit should be applied before interpolating.

The Maximum Considered Earthquake Geometric Mean (MCEG) peak ground acceleration (PGA) values of the 2009 NEHRP Recommended Seismic Provisions and the 2010 ASCE/SEI 7 Standard are calculated from the data in the downloadable files below, via the following equations: PGA = min[ PGAUH , max( PGAD84th , 0.6 ) ] for the 2009 NEHRP Recommended Seismic Provisions; PGA = min[ PGAUH , max( PGAD84th , 0.5 ) ] for the 2010 ASCE/SEI 7 Standard; where PGAUH = uniform-hazard peak ground acceleration; PGAD84th = 84th-percentile peak ground acceleration. These peak ground accelerations are each for the geometric mean of two horizontal components and a site shear wave velocity (VS30) of 760 m/s. For more information, see Chapters 11, 21, and 22 of the 2009 NEHRP Recommended Seismic Provisions and the 2010 ASCE/SEI 7 Standard. Note: The USGS Seismic Design Web Services first spatially interpolate the uniform-hazard (PGAUH) and 84th-percentile (PGAD84th) gridded values, and then combine the interpolated values via the equation above. If instead one first combines the gridded values (via the equation above) and then spatially interpolates, the resulting values will not necessarily be equal to those from the web services. For deterministic values, the lower limit should be applied before interpolating.

For designing buildings and other structures to safely resist earthquakes, the 2009 NEHRP Recommended Seismic Provisions and the 2010 ASCE/SEI 7 Standard contain maps of Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations and maps of Maximum Considered Earthquake Geometric Mean (MCEG) peak ground accelerations. Identical values from the MCER maps are also in the 2013 ASCE/SEI 41 Standard and the 2012 and 2015 editions of the International Building Code. The MCER and MCEG ground motion maps are derived from USGS National Seismic Hazard Models via the gridded values of this data release. The data files in the "Child Items" below also underlie the corresponding USGS Seismic Design Web Services. See the "Related External Resources" below for links to the building code reference documents, the USGS National Seismic Hazard Models used, and the corresponding USGS web services.

For designing buildings and other structures to safely resist earthquakes, the 2009 NEHRP Recommended Seismic Provisions and the 2010 ASCE/SEI 7 Standard contain maps of Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations and maps of Maximum Considered Earthquake Geometric Mean (MCEG) peak ground accelerations. Identical values from the MCER maps are also in the 2013 ASCE/SEI 41 Standard and the 2012 and 2015 editions of the International Building Code. The MCER and MCEG ground motion maps are derived from USGS National Seismic Hazard Models via the gridded values of this data release. The data files in the "Child Items" below also underlie the corresponding USGS Seismic Design Web Services. See the "Related External Resources" below for links to the building code reference documents, the USGS National Seismic Hazard Models used, and the corresponding USGS web services.

The Maximum Considered Earthquake Geometric Mean (MCEG) peak ground acceleration (PGA) values of the 2015 NEHRP Recommended Seismic Provisions, the 2016 ASCE/SEI 7 Standard, and the 2018 International Building Code can be calculated from the downloadable data via the following equations: PGA = min[ PGA_UH, max( PGA_D84th , 0.5 ) ] where PGA_UH = uniform-hazard peak ground accelerations PGA_D84th = 84th-percentile peak ground accelerations The data cover six distinct geographic regions: 1) the conterminous United States, 2) Alaska, 3) Hawaii, 4) Puerto Rico and the U.S. Virgin Islands, 5) Guam and Northern Mariana Islands, and 6) American Samoa. DETAILED METADATA, ABOUT THE DATA FOR EACH GEOGRAPHIC AREA, CAN BE FOUND IN THE ZIP ARCHIVE TITLED: AllMetadataMCEG.zip

The Maximum Considered Earthquake Geometric Mean (MCEG) peak ground acceleration (PGA) values of the 2015 NEHRP Recommended Seismic Provisions, the 2016 ASCE/SEI 7 Standard, and the 2018 International Building Code can be calculated from the downloadable data via the following equations: PGA = min[ PGA_UH, max( PGA_D84th , 0.5 ) ] where PGA_UH = uniform-hazard peak ground accelerations PGA_D84th = 84th-percentile peak ground accelerations The data cover six distinct geographic regions: 1) the conterminous United States, 2) Alaska, 3) Hawaii, 4) Puerto Rico and the U.S. Virgin Islands, 5) Guam and Northern Mariana Islands, and 6) American Samoa. DETAILED METADATA, ABOUT THE DATA FOR EACH GEOGRAPHIC AREA, CAN BE FOUND IN THE ZIP ARCHIVE TITLED: AllMetadataMCEG.zip

The Risk-Targeted Maximum Considered Earthquake (MCER) spectral response acceleration (S_S and S_1) values of the 2015 NEHRP Recommended Seismic Provisions, the 2016 ASCE/SEI 7 Standard, and the 2018 International Building Code are calculated from the downloadable data via the following equations: S_S = min[ S_SUH * C_RS , max( S_SD84th , 1.5 ) ] S_1 = min[ S_1UH * C_R1 , max( S_1D84th , 0.6 ) ] where S_SUH & S_1UH = uniform-hazard spectral accelerations at periods of 0.2 & 1.0 seconds, respectively C_RS & C_R1 = risk coefficients at spectral periods of 0.2 & 1.0 seconds, respectively S_SD84th & S_1D84th = 84th-percentile spectral accelerations at periods of 0.2 & 1.0 seconds, respectively The data cover six distinct geographic regions: 1) the conterminous United States, 2) Alaska, 3) Hawaii, 4) Puerto Rico and the U.S. Virgin Islands, 5) Guam and Northern Mariana Islands, and 6) American Samoa. DETAILED METADATA, ABOUT THE DATA FOR EACH GEOGRAPHIC AREA, CAN BE FOUND IN THE ZIP ARCHIVE TITLED: AllMetadataMCER.zip

The Risk-Targeted Maximum Considered Earthquake (MCER) spectral response acceleration (S_S and S_1) values of the 2015 NEHRP Recommended Seismic Provisions, the 2016 ASCE/SEI 7 Standard, and the 2018 International Building Code are calculated from the downloadable data via the following equations: S_S = min[ S_SUH * C_RS , max( S_SD84th , 1.5 ) ] S_1 = min[ S_1UH * C_R1 , max( S_1D84th , 0.6 ) ] where S_SUH & S_1UH = uniform-hazard spectral accelerations at periods of 0.2 & 1.0 seconds, respectively C_RS & C_R1 = risk coefficients at spectral periods of 0.2 & 1.0 seconds, respectively S_SD84th & S_1D84th = 84th-percentile spectral accelerations at periods of 0.2 & 1.0 seconds, respectively The data cover six distinct geographic regions: 1) the conterminous United States, 2) Alaska, 3) Hawaii, 4) Puerto Rico and the U.S. Virgin Islands, 5) Guam and Northern Mariana Islands, and 6) American Samoa. DETAILED METADATA, ABOUT THE DATA FOR EACH GEOGRAPHIC AREA, CAN BE FOUND IN THE ZIP ARCHIVE TITLED: AllMetadataMCER.zip

The 2018 Update of the U.S. National Seismic Hazard Model defines the potential for earthquake ground shaking for various probability levels across the conterminous United States and is applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy. The updated model represents an assessment of the best available science in earthquake hazards and incorporates new findings on earthquake ground shaking, seismicity, and long-period amplification over deep sedimentary basins. The new model represents an update of the seismic hazard model; previous versions were developed in 1996, 2002, 2008, and 2014. The output from the National Seismic Hazard Model is a suite of seismic hazard curves calculated on a grid of latitude/longitude locations across the conterminous United States that describe the annual frequency of exceeding a set of ground motions. Hazard curves and probabilistic hazard data and maps for VS30 equal to 760 m/s and 260 m/s (NEHRP site class B/C and D), for 0.2, 1.0, and 5.0 second periods, as well as PGA, are available for download in the "Child Items". Maps depict probabilistic ground motions with a 2 percent, 5 percent, and 10 percent probability of exceedance in 50 years. Spectral accelerations are calculated for 5 percent damped linear elastic oscillators. Additional maps and data portraying the chance of damaging earthquake shaking, probabilistic Modified Mercalli Intensity, the declustered seismicity catalog, and data used for basin amplification are also available for download in the "Child Items".