Mapping Seismic Hazard in the Central and Eastern United States

Abstract

INTRODUCTION The U.S. Geological Survey (USGS) has been publishing probabilistic seismic hazard maps for the United States since 1976 (e.g., Algermissen and Perkins, 1976; Algermissen et al., 1990). We are preparing new national maps for the 1997 edition of the NEHRP Recommended Provisions for the Development of Seismic Regulations for New Buildings , published by the Building Seismic Safety Council (NEHRP stands for National Earthquake Hazards Reduction Program). The USGS hazard maps are to be the basis for design value maps for buildings to be included in the Provisions . We are conducting a series of regional workshops to discuss the methodology and input to the maps. As of this writing, workshops have been held in the Pacific Northwest, the northeastern U.S., and northern California. We intend to make maps showing ground motions with 10% probability of exceedance (PE) in 50, 100, and 250 years. These correspond to return times of 475,...