DARPA Center for Seismic Studies Central Data Repository

Since 1982 DARPA's Center for Seismic Studies (Center) has supported
advances in seismology by providing high-quality data and by
encouraging the acceptance of standards for data formats and software.
Our primary objective is to provide for the research
community easy access to the data most important for addressing
problems in treaty monitoring seismology.

The Center pioneered the use of relational DBMS technology in
seismology, and the familiar Center for Seismic Studies database
structure has been in general use since 1984. This structure
separates the voluminous waveform data (stored in files or off-line
volumes outside the DBMS) from the parametric data that describe
detected phases, located events, and pointers to archived waveform
segments. The seismic data archived at the Center has been divided
into two distinct 'Categories', I and II. For the actual database
account names and contents, the user can use SQL*Plus to examine the
database summary tables called database_catalog and
database_descriptions on the machine hugo.css.gov.

'Category I' includes events for which an extensive suite of parameter
data and waveform segments is available on-line in the CDR. Such
high-quality data are produced by the Intelligent Monitoring System
(IMS) and the Washington Experimental International Data Center
(EIDC), and are of the type most important for investigating current
problems in monitoring seismology. The IMS has been providing Category
I data since October 1989. The network currently includes the NORESS,
ARCESS, FINESA, and GERESS, Apatity, Spitsbergen, and Kislovodsk arrays and
several three component stations throughout the Eurasian continent. Catagory I
data produced by the EIDC during the UN Conference on Disarmament/Group of
Scientific Experts Technical Test (1990 - 1991) is another valuable data source.
About 60 globally-distributed stations contributed data during the
71-day test. Both the IMS and GSETT datasets include event solutions
generated automatically by an expert system, then reviewed by an
analyst and corrected when necessary. Parameter data and waveform
segments for nearly all local, regional, and teleseismic events are
regularly migrated from the Seismic Operations LAN to the CDR. We are
also upgrading selected data from the Center's vast Category II
databases to Category I quality. Our first priority has been to build
a database in the CDR including all publicly known nuclear explosions.
The current NUCLEAR_ALL database includes waveforms from most of the
Category II databases, as well as from external sources (e.g., United
Kingdom array data, hand-digitized waveforms from Soviet stations).

'Category II' includes data which are not necessarily tied to seismic
events (i.e., detection-triggered or continuous waveforms) and are
less extensively parameterized in the DBMS. Associated waveform data
are stored on tape. The Category II archives include about 6,000
tapes with data from the Global Digital Seismic Network (the GDSN
database), the Regional Seismic Test Network (RSTN), the Chinese
Digital Seismic Network (CDSN), Natural Resources Defense Council
stations in the Soviet Union (NRDC), IRIS stations in the Formner
Soviet Union (USSR), the Norwegian arrays, and many other sources.
Altogether, these tapes contain about 800 Gbytes of waveform data.
Pointers to these data are maintained on-line in the CDR. The EVENTS
database, updated daily in the CDR from the NEIS (recent events) and
ISC bulletins, is useful as a quick reference to the Category I and II
waveforms.

Fusion of these seismic data with other useful information is another
focus of the Center. Such data include a growing database of seismic
station parameters (locations, instrument responses, etc.), satellite
imagery (from the French SPOT satellite), map graphics (color bitmaps
composed from NOAA, Defense Mapping Agency, and World Database 2
datasets), mine and quarry locations, and travel-time and
amplitude-distance curves.

A principal objective is to encourage the unassisted use of the
Center's resources by the research community. However, this is
reasonable only if users are supported with an adequate working
environment and the proper tools. Much emphasis has been placed on
providing software that allows users to review, select, and retrieve
data from the Center archives.

At the most basic level, SQL*Plus is the Oracle tool for forming
queries to relational databases in ANSI standard SQL. Once the syntax
of this language is understood, the user has nearly-unlimited
flexibility to browse and select data in the DBMS. The program
CenterView provides X Windows and ASCII interfaces to the Center DBMS
and waveform archives, using menus and forms to construct queries for
the most commonly requested data. The interface permits the user to
place limits on specified parameters constraining the selection of
events, phase detections, waveforms, and stations. Results of the
query can be reviewed on the screen with an interface that allows the
user to select subsets of the results and/or to write results to a
local disk in a variety of formats. Waveform data that are on-line in
the CDR may be retrieved by CenterView immediately, while requests for
data on tape may be generated and satisfied by the requesting party or
an operator on a semi-automated basis.