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1 EXECUTIVE SUMMARY Negotiations of a Comprehensive Test-Ban Treaty (CTBT) are now underway, and the Non-Proliferation Treaty was extended indefinitely in May ~ 995. Both ofthese are important steps in the reduction of the worldwide threat of nuclear weapons. These treaties create a need to monitor for nuclear explosions in the context of national and international efforts in nuclear arms control. Seismology, a discipline that provides the principal technology for detecting, locating, and identifying underground nuclear explosions on a global basis, is confronted with the massive new challenge of monitoring a global ban on all nuclear testing. With seismology playing a prominent role in U.S. and international treaty monitoring procedures, it is essential to plan carefully the seismological monitoring system at all levels, from the basic research programs that support the monitoring effort, to the instrumentation, to the use of the results in the national verification system. This report will address many of the key issues associated with implementing the seismological monitoring system. The United States is now in a time of pivotal decision-making, with major issues being decided that will affect the field of seismology for the next few decades. Major expenditures by the United States and other nations are now being made to provide the seismic recording and analysis capabilities essential for a cooperative international monitoring effort. In the rapidly evolving political landscape surrounding nuclear test- ban and nonproliferation treaties, there is a window of opportunity to ensure that the international seismic system will contribute broadly to multiple issues of national concern, including earthquake monitoring and basic research on earth structure and processes, as well as treaty verification functions. Small nuclear tests, such as might be part of a clandestine weapons program, produce ground vibration levels equivalent to those of thousands of natural seismic events that occur each year. And improved seismological methods will be needed to assess the nature of these sources. The vast majority of recorded events will be natural earthquakes, and the seismic recordings made for monitoring purposes will be users! for further scientific analysis and hazard assessment. Both broadband and short-period array data will be collected by the international treaty monitoring system, and all these data have multiple potential applications. The 1

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2 Comprehensive Test Ban Monitoring System large quantity of both ty pes of data offers a significant increase in the number of timely signals that can be accessed from stations around the world for earthquake monitoring and basic research applications as well as for basic monitoring applications. Rapid, widespread access to the treaty monitoring data will provide improved determination of earthquake fault mechanisms and more reliable rapid earthquake assessment and . . . ~ tsunami warning capab~t~es. This report describes ways of ensuring the multiple use of the seismic data collected by the new treaty monitoring system, along with measures needed to sustain the treaty monitoring capabilities ofthe United States into the future. The recommenda- tions address issues associated with the characteristics of the instrumentation of the international seismic monitoring system (TSMS), the critical importance of open access to the data collected by the system, and the U.S. infrastructure needed to sustain the long-term monitoring of nuclear testing treaties. The treaty monitoring data will be of very high quality but will constitute only a fraction of the total seismic data required for earthquake monitoring and basic research. The new international seismological system that is being developed presents an opportunity to break down past barriers to broad usage of data collected by treaty monitoring activities, to the benefit of all applications. The key to achieving this goal lies in the definition of the functions of the U.S. National Data Center, which will support both the international monitoring program and the national verification function. If the monitoring capability is to be maximized and other nationally important applications are to benefit, the U.S. National Data Center mission statement must include a data access obligation and appropriate funding must be identified to support this activity. Both the archiving and the distribution of the TSMS data have cost implications for the U.S. NDC. Because no specific plan has yet been put forth, the pane! did not attempt any detailed cost analyses. We have suggested what appears to be the most economical approach. History has repeatedly demonstrated that basic seismological research efforts are an essential part of the national strategy for long-term treaty verification. These are required both to enhance treaty monitoring capabilities and to ensure a pool of seismological expertise for future monitoring efforts. The research community can also play a part in the confidence-building process that is an essential element in the justification of the ISMS. These researchers will be advisors to their governments and will provide important independent checks and balances on the operations of the monitoring system, and sources of insight into the geophysical properties of regions of Earth, the nature of specific events of interest, and monitoring methods in general. In addition, the broader the user community is, the better the feedback about quality control issues and instrumentation problems. Such

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EXECUTIVE SUMMARY 3 problems are often revealed in the course of analysis of recordings for large earth- quakes, which may be ignored in the national verification effort. The specific recommendations are listed in the next section. Those concerned with Data Characteristics and Data Access have been issued, essentially in their present form in preliminary reports designed to provide timely inflation and assistance to the U.S. negotiating team in Geneva. Recommendations Continuous recordings from the high quality, globally distributed seismometers of the TSMS can be used beneficially for numerous purposes, if the seismological system has certain attributes. These include the recording system characteristics, as discussed in Chapter 3; the availability of the data to diverse seismological communi- ties, as discussed in Chapter 4; and a strong seismic research and development program, as discussed in Chapter 5. The large international investments in the new ISMS must not be underutilized by the United States, as has often been the case with data collected for nuclear test monitoring in the past. Relatively low-cost efforts can ensure maximum utilization of the data for a variety of activities in the national interest, as well as augment the research and development efforts that support U.S. treaty verification capabilities. The panel has addressed both specific technical issues and larger-scale infrastructure questions in pursuit of optimization of use of the ISMS data. The recommendations in this report have been framed to enhance U.S. activities in both nuclear test-ban monitoring and earthquake monitoring. Failure to follow through on the recommendations, especially those concerned with data accessj watt lead to duplica- tion of effort in the seismological system and underutilization of seismic data acquired at substantial cost. The primary recommendations of this report are summarized below: Data Characteristics It is important that the data characteristics of the new TSMS stations be compatible with the broad needs of seismology in general as well as fifing treaty monitoring requirements. The panel's main recommendations for data characteristics involve bandwidth and recording-system specifications. The interest in high-frequency signals from small events for CTBT monitoring has led to an emphasis on that part of the seismic spectrum in the ISMS station design, but it is technologically straightfor- ward to simultaneously record lower- frequency signals that are of primary value for

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4 Comprehensive Test Ban Monitoring System earthquake monitoring and basic research on earthquake processes and earth structure. The extended bandwidth also has important potential applications in discriminating explosion and earthquake signals. Care must be taken to ensure that lower-frequency signals are not clipped when the high-frequency signals are emphasized. This involves modest enhancement of ISMS station designs, with no reduction in high-frequency capabilities. The primary recommendations from Chapter 3 are technical in nature and are given below: Wherever possible, without degrading the ISMS's monitoring performance, extend the bandpass of the ISMS broadband three-component elements to as low as 0.003 Hz. Relax the low noise requirement to the ~ 0-20 Hz range. Re-evaluate the sample rate requirements. Relax the resolution requirements for broadband three-component elements and base the noise floor on local conditions. . Provide better specification of the sensitivity goals, emphasizing perfor mance at higher frequencies. . Specify the frequency band of the system noise requirement. Develop a mechanism to provide data in SEED (Standard for Exchange of Earthquake Data) format in addition to other formats that might be used. Reconsider the data frame length requirement. Establish separate data availability requirements for primary and auxiliary . stations. . Relax the orientation tolerance for primary station instrumentation. Data Access Within the United States Given suitable data characteristics, the ISMS data set can contribute to diverse efforts that address earthquake monitoring and basic research on earthquakes and earth structure, as well as the nuclear test-ban monitoring effort. To enable these multiple uses of the seismic data, it is important to establish convenient pathways for data access in the United States that do not interfere with the nation's primary operations of the nuclear test-ban monitoring effort. This report proposes cost-effective strategies that will provide these pathways. The key element is to ensure that the U.S. nuclear monitoring effort and the existing data archival and distribution capabilities are integrated for the mutual benefit of all seismological applications serving the nation. The primary recommendations from Chapter 4 concern policy on data access and are given below:

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EXECUTIVE SUMMARY At a minimum, the development of the ISMS should augment, not reduce, the capabilities ofthe U.S. scientific community. Therefore, it should not restrict current paths of access to existing stations nor limit access to new unclassified stations. Implementing this guideline will require attention to preexisting international relationships, treaty language, and agreements regarding seismic data exchange. The U.S. position should be that the entire ISMS seismic data set should be available in a timely manner and that these data should be unclassified. Distribution within any country would of course be the responsibility of that country's National Data Center. Therefore the U.S. government should ensure that these data are readily accessible in the United States. The U.S. ISMS National Data Center (ISMS-NDC) is expected to receive . all of the ISMS primary-network data for U.S. treaty monitoring use. The panel recommends that the U.S. ISMS-NDC should be operated under a policy that requires it to provide the U.S. scientific, disaster prevention, and earthquake monitoring communities with stable, timely access to all signals and seismic event data that it receives from the ISMS. Costs of operating the ISMS-NDC should be provided by the nuclear monitoring community; incremental system costs for external data transmission should be provided by the earthquake monitoring agencies and by agencies supporting research on nuclear explosion and earthquake monitoring. To facilitate interagency data transmission and to deal with cost issues, the ISMS-NDC should establish a multiagency advisory committee, with representation from the nuclear monitoring, earthquake monitoring, and basic research communities, to address data distribution issues. All broadband data from primary and auxiliary stations received by the ISMS-NDC should be made available to the earthquake monitoring agencies in the United States in near real time (possibly by direct rebroadcast from the ISMS-NDC or by satellite downlink). These data should be archived in and made accessible on various media through the Incorporated Research Institutions for Seismology's Data Manage- ment System (IRIS-DMS). This system has extensive capabilities for servicing diverse data requests and a willingness to distribute ISMS broadband data along with other global broadband seismic data. This approach provides a permanent on-line archive of the broadband TSMS data set, facilitates user access to the data, and greatly reduces the data-distribution load on the ISMS-NDC. Assuming the data are accompanied by quality-control information, the incremental costs involved should be borne by the earthquake monitoring agencies and by agencies supporting research on nuclear explosion and earthquake monitoring. The continuous data from auxiliary stations (most of which will not be accessed routinely by the ISMS) should continue to be archived and distributed through existing procedures of the Federation of Digital Seismographic Networks (FDSN).

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6 Comprehensive Test Ban Monitoring System Operational support for U.S. auxiliary stations should be shared by the nuclear monitoring, earthquake monitoring, and basic research agencies. Continuous data from short-per~od arrays will comprise most of the ISMS data. These data will be important for nuclear monitoring operations. Currently, the earthquake monitoring and basic research programs have limited demand for array data, but this will almost certainly grow with time. The research that supports nuclear monitoring watt require access to these data. The ISMS-NDC watt archive the array data, and it is certainly not cost effective to duplicate this archive. Therefore, a user-friendly interface should be established to provide access to the entire data set. We propose that the U.S. Geological Survey and/or TRIS are logical entities to coordinate with the TSMS-NDC to develop a user-friendly pathway to all of the array data. The incremental costs involved in establishing and maintaining this pathway should be borne by agencies supporting research on nuclear explosion and earthquake monitoring. Seismic event data (arrival times, amplitudes, ray parameters, final event bulletins) generated by the ISMS should be made available through appropriate National Data Centers to the U.S. earthquake monitoring agencies as well as to the International Seismological Centre (ISC) to enable improvements in the seism~city bulletins produced by those agencies. Electronic transmission should minimize the costs. The Group of Scientific Experts Technical Test #3 (GSETT-3) experiment can be used to develop and test the data distribution pathways recommended above. The data from GSETT-3 currently being collected by the ISMS-IDC can be sent directly to the USGS from the ISMS-IDC until such times as it is possible to transmit continuous data from the TSMS-IDC. Research Feedback Monitoring compliance with a CTBT poses many unprecedented technical and scientific challenges, and there will be a continuing need for basic and applied research, as well as advanced technology and automated systems development, in all of the disciplines that contribute to the monitoring system (OTA, 19881. It is especially important that the use of comparatively new technologies such as Synthetic Aperture Radar (SAR) and the Global Positioning System (GPS) be considered for integration into the base data that will continue to come from continuous seismic recording. It is essential to sustain basic research activities that will train the next generation of seismological experts vital to long-term treaty monitoring. Furthermore, it is critical to have effective means by which basic research developments are carried out, the results are tested in operational settings, and useful, cost-effective advances are implemented in the operational system. This holds for both the ISMS and the U.S. monitoring

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EXECUTIVE SUMMARY 7 systems. Chapter 5 considers this topic in detail. It is assumed that the mission for support of monitoring research will continue to reside within the Department of Defense (DOD) and the Department of Energy (DOE), with supporting activities by the USGS and seismological research community. If these agency roles change, the basic seismological research effort must be maintained by those responsible for the functions of monitoring, verification, and hazard reporting. The primary recommendations from Chapter 5 concern management issues and are given below: The DOD and DOE both have valuable assets and experience that can contribute to the seismic research and development program supporting CTBT monitoring. Continuation ofthe current coordinated research effort is in the best interest of the United States. The overall research effort of the DOD and DOE programs should be overseen by an advisory group that addresses both research coordination and relevance. This advisory group should have access to policy-level management. The DOD research and development effort in support of monitoring a CTBT should have a balanced program involving basic research, exploratory development, and advanced development efforts (the standard 6. I, 6.2, 6.3 categories of DOD research efforts), and an innovative technologies effort (traditionally the role of the Advanced Research Projects Agency) servicing the end-user, which is currently the Air Force Technical Applications Center (AFTAC). The Air Force basic research (6.~) program in seismology, currently administered by the Air Force Office of Scientific Research (AFOSR), should be sustained, possibly with some short-term expansion, to maintain an influx of researchers and fundamental research on long-term problems associated with seismological monitoring of a CTBT. The Air Force exploratory development (6.2) program in seismology, currently administered by the Air Force Phillips Laboratory, should be provided with a stable base for external funding to enable effective development and transfer of promising research and technologies from the AFOSR basic research program to the Air Force operational environment. The Air Force advanced development research (6.3) program in seismology currently administered by AFTAC should be sustained. The development of the prototype ISMS International Data Center and other advanced computer technology capabilities and high risk/high return research topics currently sponsored by ARIA should be sustained. . . The DOE research and development effort in support of seismic monitoring of a CTBT should sustain its directed research program. involving national laboratory and externally funded seismic research of direct relevance to the end-user, which is currently AFTAC.

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8 Comprehensive Test Ban Monitoring System A knowledgeable, responsible advisory mechanism should oversee the combined DODiDOE research effort to ensure relevance and continued coordination of the programs. lmprovect communication between and among the DOD operational units and researchers in the basic and exploratory development programs is essential. Release of information about operational methodologies and procedures, lists of problem events, and comparisons of seismic bulletins from different communities are among the activities that could enhance responsiveness of the research community to the operational requirements. Communication across the various elements ofthe monitoring and research communities should be fostered by symposia, workshops, site visits, and advisory panels. Focused experiments, involving broad communities, should be conducted to concentrate effort on important issues To the extent possible and consistent with national security considerations, an unclassified experimental test bed facility that replicates the basic U.S. and ISMS analysis procedures should be established and made broadly available to enable new . developments to be tested in a realistic environment, enhancing transfer of applied research results into the operational systems. A research data base of important seismic recordings should be assembled and maintained. Ground truth data bases should be provided to the test bed to assess performance of new methods. A results data base and literature guide should also be established. . Major research efforts that have potential benefits for both nuclear test and earthquake monitoring, such as enhanced association algorithms, new regional event location procedures, and event location procedures in three-dimensional models should be coordinated through interagency working groups (for example, bridging between AFTAC and the USGS, which conducts earthquake monitoring). . A program in which postdoctoral fellows and visiting researchers are able to work at the international Data Center, as well as the U.S. National Data Center, would provide effective communication between the operational and research environ- ments. Implementing the recommendations of this report regarding data characteristics, data distribution, and research infrastructure will ensure that the United States derives maximum benefit from its participation in the ISMS. Optimal multiple use of the seismic data streams for nuclear test treaty monitoring, earthquake monitoring, and basic earth science research will be enabled. In addition, U.S. treaty monitoring efforts will continue to have the critical influx of research innovations, technical developments, and personnel vital to an effective monitoring operation.