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l APPENDIX B RESEARCH TOPICS FOR CTBT SEISMIC MOINTORING This appendix identifies some of the many topics requiring continued seismological research in support of the treaty verification needs of the United States. Several research planning documents have been produced by AFTAC, ARPA, and DOE that emphasize the focused needs of applied research efforts. The DOE summary of research needs is reproduced in the next few pages. Somewhat less consideration has been given to the objectives that should guide the basic and applied research programs in seismology that are now being managed by the Air Force Office of Scientific Research and the Air Force Phillips Laboratory. These organizations are in the process of corrunission~ng a study by the National Research Council to help develop a plan for relevant basic research. While the detailed plan is not yet available, it is clear that it will identify some long-standing priority areas, such as improved theoretical and computational ability to model seismic waves in three-dimensional heterogeneous media; improved theory for excitation of seismic waves from diverse sources such as quarry blasts, chemical explosions, nuclear explosions and earthquakes; and new methods for characterizing the wave propagation effects of diverse geological environments, along with the effects on seismic event location and identification. Some of these issues are considered in the research plans for the applied and advanced development programs, but they require a longer-term approach than is characteristic of the latter programs. The basic research effort is also essential for drawing well-trained seismologists into the arena of treaty monitoring issues, to ensure a long-term supply of expertise required for the long-term task of reliably monitoring a CTBT. The summary of the DOE Seismic Monitonng Research Plan (pages A3-A5; DOE, ~ 994) is reproduced here as an illustration of the types of research that must be sustained for the U.S. nuclear monitoring effort. 73

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74 Comprehensive Test Ban Monitoring System Seismic Monitoring Research Goal: The seismic mon~tonng research element's goal is to provide improvements in the seismic monitoring capabilities, primarily in regional location and identification and, to a lesser extent, in detection and characterization, to meet U.S. national requirements for CTBT monitoring. Improvements in all these Unctions will be made in the context of evolutionary upgrades to the prototype U.S. National Data Center (NDC). To the extent appropriate, these improvements will also be incorporated into the prototype International Data Center (IDC) being developed by the Advanced Research Projects Agency (ARPA) for use in the GSETT-3 experiment planned by the Group of Scientific Experts (GSE). Products: The seismic monitoring program element will provide methodologies that define and improve the monitoring performance in high-interest regions and, to a lesser extent, the remainder of the globe; proven, documented algorithms for accurate event detection, location, identification ,and characterization; a basic understanding of the factors that control the performance of the algorithms so that they can be tailored to specific sites and regions; and an overview of the monitoring challenges posed by conventional explosions and the measures that can be taken to address these challenges. Supporting data bases, raw input information, procedures, and reports will accompany the final versions of the regional characterizations to AFTAC. The information that is acquired and the algorithms that will be developed will be applied (due to budget constraints) to two regions of interest only: southern and central Asia and the Mid-East/North Africa. Approach: Event detection, location, identification, and characterization functional elements of the CTBT monitoring problem have common requirements for seismic data and regional characterization information. Task ST is intended to provide regional geophysical and geological information about the Mid-East/North Africa and southern and central Asia that can be acquired from existing sources. Tasks S2 and S3 address the detection and location capabilities, respectively, in these regions. Task S4 develops an empirical understanding of existing identification concepts (discriminarlts) by testing them on data from the Mid-East/North Africa and southern and central Asia and quantifying their performance. Tasks S5 and S6 are efforts to understand the physical basis for location and discrimination, respectively, in order to develop methods that can be transported from one region to another. Task S7 defines and executes field studies to obtain significant new information or to resolve critical location and discrimination

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APPENDIX B: RESEARCH TOPICS FOR CTBT SEISMIC MONITORING 75 issues. Task SS integrates the various elements across the projects in a comprehensive report. Task Overview Task 51. Regional Characterization The goal of this task is to provide geological and geophysical information for the regions of high interest for use by Tasks S2-S6. Sources of natural and man-made seismicity and cultural noise will be identified and characterized. This information will be acquired from research either in the region of interest, including possible calibration experiments conducted under Task S7, or from technical contacts in the region and from seismic monitoring. It-will be synthesized into reports on and data bases of velocity structures, travel-time curves, regional characterization of wave propagation, attenuation characteristics, and evasion assessments. Task S2. Develop Detection, Phase Identity cation, and EventAssociation (DPlEAJ Techniques The goal of this task is to develop new and/or improved regionally dependent algorithms for detection, phase identification, and event association in the Mid-Eas~orth Africa and southern and central Asia regions. Task 53. Develop Empirical Location (Epicenter and Depths Techniques The goal of this task is to develop improved epicenter and depth estimates. These are likely to depend upon the properties of the specific regions. Significant improvements in epicenter location capability will benefit all aspects of treaty verification. More precise locations would greatly reduce the effort required in an on-site inspection. Event identification would benefit from improved depth estimates. Task S4. Develop Empirical Discriminants in Areas of Interest The goal of this task is to test discr~minants and determine the performance of existing and potentially useful regional ones in the southern and central Asia and Mid-East/North Africa regions. Both individual discnminants and combinations of discriminants watt be studied.

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76 Comprehensive Test Ban Monitoring System Task S5. . Develop Models for Regional Propagation and Event Location The goal of this task is to develop an understanding of the physical properties of both the regions under consideration and the recording network that controls the accuracy of the location and depth estimation efforts. The empirical results of tasks S2 and S3 will be used to develop a mode! that embodies the important propagation features observed in the region. The mode] will provide a basis for the validation, refinement, extension, or redefinition of existing location and depth estimation techniques and the development of new ones. Task 56. Develop Models for D`scriminants The goal of this task is to develop a physical understanding of the factors controlling the performance of existing event discrimination procedures. The results of Task S4 will be used to develop a mode] of the performance of discrimination techniques that could be generalized for all regions of interest. This task will provide a basis for the validation, refinement, extension, or redefinition of existing discrimination techniques, for the development of new techniques, and for the prediction of the performance of the discriminants in new regions. Task S7. Perform Field Studies The modeling undertaken in tasks SS and S6 will generate key questions regarding regional propagation and event identification that can be addressed only by field studies. Two types of field studies are envisioned: passive and active. In a passive field study, portable instrumentation would be deployed in the vicinity of targets of Opportunity where seismic activity is anticipated. These could be earthquake aftershocks or routine blasting at mines or construction sites and other geologic settings of interest. This kind of field study is adequate for calibration of propagation models used in event location but would be inadequate for the explosion phenomenology development needed for event identification. In this latter case, source location and timing are critical. Therefore, an active experiment in which the experimentalists specify the time, location, and other source parameters is required. This task will design and implement both types of experiments, but only the active ones will satisfy the requirements of both the modeling aspects of location (S5) and identification (S6) simultaneously. /

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APPENDIX B: RESEARCH TOPICS FOR CTBT SEISMIC MONITORING 77 Task 58. Integrate Results This task integrates the results obtained in the various components ofthe seismic research project. For example, the magnitude of the mine monitoring problem for a given region will be summarized in a report drawing on the results of S I, S3, and S4.

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