US1hz050 1:15M arc

Probabilistic seismic-hazard maps were prepared for the conterminous United States portraying peak horizontal acceleration and horizontal spectral response acceleration for 0.2- and 1.0-second periods with probabilities of exceedance of 10 percent in 50 years and 2 percent in 50 years. This particular data set is for horizontal spectral response acceleration for 1.0-second period with a 10 percent probability of exceedance in 50 years. All of the maps were prepared by combining the hazard derived from spatially smoothed historic seismicity with the hazard from fault-specific sources. The acceleration values contoured are the random horizontal component. The reference site condition is firm rock, defined as having an average shear-wave velocity of 760 m/sec in the top 30 meters corresponding to the boundary between NEHRP (National Earthquake Hazards Reduction program) site classes B and C.

For more information online visit:,, and

Data and Resources

Additional Info

Field Value
Last Updated March 16, 2022, 10:35 (CDT)
Created February 18, 2022, 05:32 (CST)
dcat_issued 2018-03-13T20:21:03.000Z
dcat_modified 2018-11-09T02:45:09.000Z
dcat_publisher_name AmeriGEOSS