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Appendix A Survey of Regional Seismic Networks In preparing this report, the panel considered it essential that the current status of regional seismic networks be examined. A rapid assessment of basic information was performed through a mailed questionnaire and fol- low-up telephone call. The panel believes that all major regional networks were contacted and that any omissions would have only a minor effect on the tabulation. The questionnaire, Figure Al, was sent to all network operators. The results of the survey have been divided into two parts. Those rel- evant to budgetary considerations are discussed in detail in Chapter 3 of the main report, (in the section titled, "Are Regional Networks Cost-Effective?". Other survey results are summarized in Table Al, and several findings that characterize the overall activity of regional seismic networks in the United States are highlighted below: There are nearly 50 operators of regional networks in the United States. A rough breakdown with some overlap is as follows: at least 24 universities operate regional networks (some combining several different networks into one overall operation); about 8 federal agencies operate some 14 networks; at least 6 networks are operated by state agencies; and several networks are operated by private utilities or geotechnical firms. . A total of 1,508 seismograph stations are operated in permanent or quasi-permanent, regional or quasi-regional networks. (This total is prob- ably accurate to within 5%.) Eight California or California-Nevada networks account for over 600 stations, or about 40% of the total. The U.S. Nuclear Regulatory Commission currently provides full or 49

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52 APPENDIX A Panel on Regional Networks 1988 Information Survey A MEMBER OF WE PANEL WILL CONTACI~ YOU SOON BY TELEPHONE REQUESTING THIS INFORMATION. AT THAT TIME YOU WILL ALSO BE ASKED TO FORWARD A LISTING OF STATION COORDINATES. 1. Network name and operating institution 2. Total number of stations 3. Total current annual funding for network operations alone, exclusive of research 4. Relative contributions to current network support: a. Federal USGS ARC Other Total Federal b. State c. Private TOTAL % % 5. Number of three-component stations in network 6. Number of completely digital stations in network (i.e., from sensor through recording, not just recording alone) 7. Number of stations significantly upgraded during last 5 years 8. Age of computer in use for network recording 9. Number of students (undergraduate and graduate) involved in network seismology doing either analysis % _% % 100 % or research on network data. Please estimate the total FlEs (full-time equivalents) also. Figure Al. Sample questionnaire. $ Students Al ks partial support for some 14 seismic networks in the eastern United States, totaling some 241 stations. This represents only 15% of the national total but more than 70% of the regional network seismic stations operated east of the Rocky Mountains. Complete phase-out of this Nuclear Regulatory Commission support is scheduled for 1992. Less than 10% of the seismic stations currently operated by regional networks record the full three-dimensional seismic wavefield. Less than 4% are fully digital from sensor to recorder. Only 10% of the stations have been significantly upgraded in the last five years. Some 123 students in seismology were fully or partially supported by seismic network operations in 1988.