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6
The Future:
A National Seismic System
Forecasting the future of regional seismic networks is facilitated because
that future is severly circumscribed. The panel has reported on the follow-
ing persistent themes, already well set, which will control the next one to
two decades of observational seismology in the United States:
· First, regional seismic networks, as currently configured and supported,
do not have a long-term future; they will remain, at best, static in the
western United States and will largely disappear in the East.
.
Second, the rationale for development of the USNSN is compelling.
However, since design and implementation of the USNSN are already well
under way and funding for the eastern portion has already been secured, this
is largely an after-the-fact finding.
.
Third, the functions and data products of the USNSN are sufficiently
different from those of the regional networks that the former cannot replace
the latter. Even if completed nationwide, the USNSN will not eliminate the
need for regional seismic networks.
The above themes, which the panel considers are amply supported in
Heaton et al. (1989) and in this report, prompt reconsideration of the central
recommendation of the Panel on National, Regional, and Local Seismograph
Networks (Committee on Seismology, 1980), which is quoted in the preface.
Implementation of a "rationalized and integrated" system consisting of a
partnership between the USNSN and a confederation of existing regional
seismic networks is also the central recommendation of the current Panel on
Regional Networks. But now, 10 years later, the needs cited by the 1980
38
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THE FUTURE: A NATIONAL SEISMIC SYSTEM
39
panel have become a crisis, the national network of "technologically ad-
vanced observatories" is close to becoming a reality, and a detailed functional
framework and specific funding requirements have been identified. The
total concept is called the National Seismic System.
ADVANTAGES OF A NATIONAL SEISMIC SYSTEM
It is important to reemphasize that the USNSN will not meet the need for
data that can be obtained only through the dense spacing of individual
stations in the typical regional network. The resolution required for the
definition of local active tectonic structures cannot be achieved by the pro-
posed national effort. Variations in propagation and seismic wave amplifi-
cation, important in the assessment of earthquake hazards on a regional and
local scale, cannot be measured by the USNSN. And finally, the USNSN
cannot replace the training facilities and intellectual focus for seismological
education and research that the regional networks currently provide at many
universities throughout the country. However, the USNSN will provide a
uniform, national earthquake recording capability that currently does not
exist. Indeed, the planned national network and existing regional networks
would complement each other, and together if the former is developed and
the latter continue to exist provide an unprecedented source of seismological
data for public services, education, and basic and applied research.
This combination of regional and national networks provides a unique
opportunity to significantly advance seismic monitoring, data collection,
data distribution, and seismological research in the United States within the
next few years. This opportunity will be translated into reality only through
close cooperation and coordination between the regional and national efforts
and through the integration of certain aspects of their activities. The advantages
that may be realized from a partnership of the regional and national network
efforts include the following:
.
Use of USNSN facilities could reduce communications costs. Expen-
sive, often unreliable, and capacity-limited ground line communication links
used by the regional networks are not very suitable for the transmission of
seismic data. The satellite-based seismic data communications system be-
ing developed for the USNSN could revolutionize regional operations in
that it will provide more reliable, more flexible, and less expensive commu-
· . .
neatens service.
Regional networks could provide maintenance and facility support for
national network stations located within the monitoring area of the regional
network. The national network would benefit through reduced operational
costs. The host regional network would benefit by having direct access to
the communications links of the USNSN.
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40
ASSESSING THE NATION'S EARTHQUAKES
The sharing of communication links and other facilities would force
both the regional and the national networks to adhere to certain standards of
data quality and format.
· With such standards in effect, it would be easier to share and ex-
change software used in routine data analysis at both national and regional
data centers. The standardization of data formats and software would allow
data to be shared between regional networks and give easy access to the
data from the national network.
· The national network could provide a framework or forum to draw the
regional networks together to discuss and resolve common problems. The
forum could prove to be an effective focus for the activities of the regional
network operators and spur development of a body with a strong and uni-
fied voice on behalf of the concerns of the regional networks.
Thus, from both the state and the national perspective, there appears to
be an opportunity for substantial benefit if the regional and national net-
works work together closely.
Finally, the panel examined the question of whether linkage with the
USNSN is the only viable alternative for the regional networks and concluded
that this is indeed the case. As has been shown, maintaining the status quo
in network operations clearly is not an option. The most nearly related
programs are the global network and portable array (PAS SCAL) of the
Incorporated Research Institutions in Seismology (IRIS). However, these
programs are complementary to a National Seismic System, and IRIS has
specifically avoided involvement with permanent arrays, although modern-
ized regional networks would contribute greatly to such PASSCAL goals as
three-dimensional imaging of the earth's crust. These reasons, combined
with the fact that planning and funding for the USNSN are already well
advanced, make a National Seismic System the best and only logical choice
for the future of regional seismic networks. As the U.S. Geological Survey
has already been assigned the role of developing the USNSN, it would play
a major part in implementing the proposed system.
CURRENT AND PROJECTED COSTS OF A
NATIONAL SEISMIC SYSTEM
A National Seismic System cannot become a reality without the infusion
of new funds. Currently, there are no new monies designated to (1) expand
the USNSN to the western United States, (2) operate and maintain the
USNSN beyond current NEIC resources, (3) replace the loss of $2 million
in Nuclear Regulatory Commission regional network support, (4) replace
and modernize aging and obsolete regional network instrumentation and
equipment, or (5) provide for data links between the USNSN and the regional
networks.
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THE FUTURE: A NATIONAL SEISMIC SYSTEM
4
1
Based on its survey of network operators (Appendix A), the survey of the
Ad Hoc Committee on Regional Networks (ACORN, 1986), and discussions
with federal agency officials, the panel estimated that the FY 1989 annual
apportionment of federal seismic network funds is approximately as follows:
$1.5 million (USGS external networks), $3.0 million (USGS internal networks),
$1.0 million (NEIC), $2.0 million (Nuclear Regulatory Commission), $2.0
million (DOE), and about $0.2 million (U.S. Bureau of Reclamation), yield-
ing a total of nearly $10 million. This estimate does not include support for
global networks or the restricted-use seismic operations of the Department
of Defense. This, then, represents the approximate current expenditure for
operations that would come under the aegis of the proposed National Seismic
System.
The panel has not attempted a detailed analysis of projected costs for full
implementation of a National Seismic System but has examined the question
in sufficient depth to make firm recommendations in Chapter 7. For example,
at least 65—and perhaps as many as 90- new stations will be required to
complete the USNSN. At approximately $90,000 per station, the panel has
conservatively estimated that 55 million will be needed for expanding the
USNSN nationwide. Cost estimates for upgrading a typical regional network
station range between $12,000 and $25,000, depending largely on whether
broadband sensors are selected. If approximately one-third of the 1,500
regional network stations are modernized in the next five years, funding on
the order of $10 million will be required for this element of a National
Seismic System. These and other costs projected for full realization of a
National Seismic System are included in Recommendation 6 of the next
chapter.
Representative terms from entire chapter:
national seismic
