The Advanced National Seismic System

Abstract

The Advanced National Seismic System (ANSS) is a major national initiative that will serve the needs of the earthquake monitoring, engineering, and research communities as well as national, state, and local governments, emergency response organizations, and the general public. U.S. Geological Survey (USGS) Circular 1188 (a report submitted to Congress in 1999) advocates development of an ANSS of more than 7,000 new digital seismographs. New generations of digital seismic recorders and sensors make it possible to record motions over wide ranges of amplitude and frequency, removing the need for separate and specialized communities based on instrumentation type. Under the ANSS plan, the current United States National Seismic Network (USNSN) will be expanded to at least 100 stations in order to provide uniform national coverage (Figure 1). A total of 1,000 digital seismographs will be deployed within regional earthquake networks to replace existing analog equipment (Figure 2). The remaining 6,000 seismic stations will be located in urban areas with significant seismic risk (Figure 3). About 3,000 of these instruments will be flee-field or reference sites and the other 3,000 instruments will be installed in buildings and other structures of interest. Most of the instruments deployed in the ANSS will transmit their data in real time to regional data collection centers. Installation of more than 7,000 new digital seismographs that can record motions up to 2 g would represent an order of magnitude increase in the number of instruments in the United …