The National Seismic Hazard Mapping Project
Earthquakes produce effects which can cause damage and loss of life. These effects, called hazards, include ground shaking, landslides and rockfall, and ground rupture (surface faulting). In general, the hazard that produces the most widespread damage and loss of life is ground shaking, because it can cause building failures and collapses at distances tens to hundreds of kilometers from the earthquake fault rupture. Recent research has focused on producing national and regional maps of probabilistic earthquake ground shaking. These maps integrate the results of research in historical seismicity, paleoseismology, strong motion seismology, and site response. The maps take into account all the possible locations and magnitudes that can happen in alternative future hypothetical earthquake histories. The maps have been produced by the USGS staff since the early 1970’s, in close cooperation with engineers and building officials involved in producing building codes for earthquake-resistant building construction. As of the year 2000, all US model building codes will incorporate ground motion hazard maps derived from the USGS studies.