Updated Guidelines for ANSS Instruments

Abstract:

In 2008 the Advanced National Seismic System (ANSS) of the U.S. Geological Survey (USGS) and cooperating universities and institutions issued USGS Open-File Report 2008-1262 (OFR) containing detailed guidelines for the performance of instrumentation to be used by the ANSS. Here we report an update underway to these guidelines to take account of lessons learned, changing technology, and expanding user desires; in a few instances, performance matters that are very hard to test in practice are either modified or removed. Instrument classes are defined in the OFR in terms of amplitude resolution and cost; because relevant technologies have advanced substantially in these six years and a number of groups have begun to explore the use of relatively inexpensive, entirely host installed and operated Class C systems, the guidelines for strong-motion sensors are being expanded to include detailed guidelines for them rather than just anticipating them. As always, Class A systems will form the state-of-the-art backbone of any network, with Class B filling in spatially and in areas otherwise not covered well. Class C systems would be an additional step in making networks denser by providing very inexpensive hardware, installation, and maintenance to fill in additionally between Class A and B sites, for example in a high-seismicity urban area, with Class A sites every 4–6 km, Class B every 2–3 km, and Class C at <1 km spacing. Class C devices would be both installed and maintained by hosts, not institutions, and therefore also would be economical for extending coverage in regions with widely spaced or rare large seismicity, such as the central and eastern U.S.