Geologists and seismologists in the United States have been compiling and publicizing databases on possible sources of earthquakes including active faults since early 1970s. The ideas about the database and risk assessment have evolved in close response to public demands raised by such unforeseen earthquake hazards in 1 989 Loma Prieta earthquake and 1994 Northridge earthquake. Though the forecasts of future earthquakes failed repeatedly, the scientific communities always analyzed the failure and improved the knowledge and technology. The faultrupture hazard zone mapping under the Alquist-Priolo act was supplemented by the seismic hazard mapping of liquefaction and landslides. Probabilistic earthquake hazard mapping of Southern California and entire United States clearly demonstrated the advantages of regional ground shaking assessment to the evaluation of fault activity.