USGS NATIONAL SEISMIC HAZARD MAPS: UNIFORM HAZARD SPECTRA, DE-AGGREGATION, AND UNCERTAINTY

The U.S. Geological Survey (USGS) recently completed new probabilistic seismic hazard maps for the contiguous United States, and in June 1996 placed them on the World Wide Web. This paper briefly summarizes the methodology used to make the maps and presents analyses of the results. An important aspect of the methodology is the use of alternative models of seismicity, fault recurrence, and ground-motion relations in a logic tree formalism. The contiguous U.S. was divided into a central and eastern U.S. (CEUS) portion and a western U.S. (WUS) portion, based on the difference in ground-motion attenuation.