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 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 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.

The Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations of the 2020 NEHRP Recommended Seismic Provisions and 2022 ASCE/SEI 7 Standard are derived from the downloadable data files. For each spectral period and site class, the MCER spectral response acceleration (S_aM) is calculated via the following equation: S_aM = min[ S_aRT , max( S_a84th , S_aDLL ) ] where S_aRT = risk-targeted spectral acceleration S_a84th = 84th-percentile spectral acceleration S_aDLL = deterministic lower limit spectral acceleration

The Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations of the 2020 NEHRP Recommended Seismic Provisions and 2022 ASCE/SEI 7 Standard are derived from the downloadable data files. For each spectral period and site class, the MCER spectral response acceleration (S_aM) is calculated via the following equation: S_aM = min[ S_aRT , max( S_a84th , S_aDLL ) ] where S_aRT = risk-targeted spectral acceleration S_a84th = 84th-percentile spectral acceleration S_aDLL = deterministic lower limit spectral acceleration

The Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations of the 2020 NEHRP Recommended Seismic Provisions and 2022 ASCE/SEI 7 Standard are derived from the downloadable data files. For each spectral period and site class, the MCER spectral response acceleration (S_aM) is calculated via the following equation: S_aM = min[ S_aRT , max( S_a84th , S_aDLL ) ] where S_aRT = risk-targeted spectral acceleration S_a84th = 84th-percentile spectral acceleration S_aDLL = deterministic lower limit spectral acceleration

The Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations of the 2020 NEHRP Recommended Seismic Provisions and 2022 ASCE/SEI 7 Standard are derived from the downloadable data files. For each spectral period and site class, the MCER spectral response acceleration (S_aM) is calculated via the following equation: S_aM = min[ S_aRT , max( S_a84th , S_aDLL ) ] where S_aRT = risk-targeted spectral acceleration S_a84th = 84th-percentile spectral acceleration S_aDLL = deterministic lower limit spectral acceleration

The Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations of the 2020 NEHRP Recommended Seismic Provisions and 2022 ASCE/SEI 7 Standard are derived from the downloadable data files. For each spectral period and site class, the MCER spectral response acceleration (S_aM) is calculated via the following equation: S_aM = min[ S_aRT , max( S_a84th , S_aDLL ) ] where S_aRT = risk-targeted spectral acceleration S_a84th = 84th-percentile spectral acceleration S_aDLL = deterministic lower limit spectral acceleration

The Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations of the 2020 NEHRP Recommended Seismic Provisions and 2022 ASCE/SEI 7 Standard are derived from the downloadable data files. For each spectral period and site class, the MCER spectral response acceleration (S_aM) is calculated via the following equation: S_aM = min[ S_aRT , max( S_a84th , S_aDLL ) ] where S_aRT = risk-targeted spectral acceleration S_a84th = 84th-percentile spectral acceleration S_aDLL = deterministic lower limit spectral acceleration