Strong-motion recording in the United States has roots in the World Engineering Congress that convened in Tokyo in 1929. American engineers returned from these meetings convinced there was an immediate need for the United States to develop a rugged seismograph able to record potentially damaging ground motions and to monitor the response of critical structures during strong local earthquakes. In 1931, Congress allocated additional funds to the U.S. Department of Commerce, Coast and Geodetic Survey (C&GS) for establishment of an engineering seismology program, including the development of a strong-motion seismograph (accelerograph), and the implementation and operation of a national strong-motion network. The first accelerograph, a modification of the Wood-Anderson seismograph, was designed by the National Bureau of Standards in the Department of Commerce. In 1932, the C&GS set up the Seismological Field Survey in California with headquarters in San Francisco.
The first U.S. accelerographs were installed in southern California in the summer of 1932. Following the successful recording of strong-ground shaking during the 1933 Long Beach earthquake, the network was expanded to more than 50 instruments in the western United States including some at the upper levels of buildings in the Los Angeles and San Francisco areas. The C&GS operated all strong-motion instrumentation in the United States regardless of ownership, but in 1963 the first “modern” accelerograph was developed leading to the establishment of instrumentation programs by many other organizations. Network responsibilities were transferred to the National Oceanic and Atmospheric Administration’s earthquake program in 1970. By 1972 the network included 575 accelerographs at permanent stations located throughout the United States and in Central and South America. In 1973 (with National Science Foundation funding), the entire strong-motion program was absorbed by the U.S. Department of the Interior, U.S. Geological Survey, as part of the National Earthquake Hazards Reduction Program.
The NSMP and it’s predecessors have evolved over more than eight decades. At times some 1200 stations have participated in the National Strong-Motion Network (NSMN). The NSMP currently operates over 1,000 strong-motion instruments at over 700 permanent stations located in 33 States and the Caribbean. The NSMN is primarily the result of cooperative efforts with many other Federal, State, and local agencies, private companies, and academic institutions.
The NSMP is part of the USGS Earthquake Hazards Program, and its main campus location which is at the Earthquake Science Center in northern California. NSMN Operations activities are coordinated with a field office in Pasadena, California.