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OCR for page 73
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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Representative terms from entire chapter:
central asia
