The Maximum Considered Earthquake Geometric Mean (MCEG) peak ground acceleration (PGA) values of the 2015 NEHRP Recommended Seismic Provisions and the 2016 ASCE/SEI 7 Standard are calculated from the data in the downloadable files below, via the following equation:
PGA = min[ PGAUH , max( PGAD84th , 0.5 ) ]
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 the "Related External Resources" below.
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.
