As in previous years, the primary focus of the SCEC Data Center (SCEC_DC) during 1997 was to provide an on-line, and near "real time" archive to seismological data for Southern California. The SCEC_DC also continued in its outreach role to SCEC researchers and community, the public, and educational and government agencies. Access to the SCEC_DC is primarily via the WWW, "finger quake", and individual research accounts (which allow sorting and extracting of event driven data in various formats) (Figure 1). Rates of access to the SCEC_DC via the WWW have nearly quadrupled from 120,000/month in 1996 to about 500,000/month in 1997. Although the commercial sector continues to make up the largest percentage of WWW access to the SCEC_DC, rates of access by educational institutions and government agencies are also steadily increasing (Figure 2).
Much of the Data Center's efforts were focused on improving and adding to the existing WWW interfaces. Users can now interactively search and retrieve data in a variety of formats from the SCEC_DC hypocenter and phase catalogs on the WWW. Since its implementation, the WWW access to the catalog/phase data is used approximately 1000 times/month. Interactive current seismicity maps for California (developed by the USGS Menlo Park) were implemented this year, and are available via the URL http://www.data.scec.org/recenteqs. This effort includes the exchanging of data and the mirroring of WWW sites between Northern California and Southern California, and will eventually include data exchange with the University of Nevada, Reno. Mirroring these sites ensures the availability of earthquake information after a large earthquake.
In conjunction with the Education Working Group, the SCEC_DC has participated in the development of the seismicity module "Investigating Earthquakes through Regional Seismicity". Many of the products and data to be used in exercises by the students utilize data from the SCEC_DC database. The module and other WWW products were presented at the annual SCEC meeting, and at a workshop "Earthquakes on the Internet" for SCEC partnership schools held at Caltech on November 8th. The response to all of these products has been excellent (Figure 2).
Processing of backlogged seismological data focused on completing the retrieval of waveforms and attribute files from 181 SCSN 9-track tapes, storing them on the Jukebox system and preparing them for processing. Processing of this data involves relocating hypocenters, determining magnitudes, and incorporating this data into the SCEC_DC database. In addition to the 1983 data, copying of SCSN data from 9-track tapes to DAT tapes has been completed for 1000 1980 tapes, and 168 1979 tapes. Efforts on retrieving and processing this data have been hampered by inadequate or non-existent documentation of the data formats of these data.
The on-line SCEC_DC archive has increased to 500 Gbytes of SCSN data, 10.5 Gbytes of GPS data, 13 Gbytes of triggered broadband data, and 9 Gbytes of portable instrument data from the Joshua Tree, Landers and Northridge earthquake sequences (Figure 3). The Northridge data includes the data from the NEAR experiment and GEOS data. Waveform data are still extracted primarily via individual user accounts and researchers have indicated that this is largely their preferred method of waveform retrieval.
The databases Datascope, Oracle and Sybase were evaluated, compared and priced this year. The decision was made to implement the ORACLE database because of its ability to replicate data between a real-time seismic processing system database and the database on the Data Center, provide a hot-backup system (making the database available even if the Data Center machine becomes unavailable), record locking and backup utilities as well as other system administration tools. This decision was also influenced by the fact that IRIS has implemented an ORACLE database, the NCEDC is planning on implementing a commercial database (probably ORACLE), and Caltech has an existing 5-year contract with ORACLE which was signed this year.
http://www.data.scec.org/recenteqs
"Recent Earthquakes in California and Nevada"
http://scec.gps.caltech.edu/catalog-search.html
"Interactive search of SCEC_DC catalog and phase archive"
http://www.data.scec.org/SCEC-MANUAL.97.html
"SCEC Data Center User Manual"
http://www.data.scec.org/bymonth.html
(in coordination with Education Working Group)
" Monthly Time-Lapse Animations of Seismic Activity in Southern California"
http://www.data.scec.org/yearanms.html
(in coordination with Education Working Group)
"Yearly Time-Lapse Animations of Seismic Activity in Southern California"
PUBLICATIONS
Marquis, J. & Hafner, K, 1997, Southern California Seismicity - "Real-time", Historical and Educational Products Available on the WWW at the SCEC_DC SCEC Annual Meeting
November 8, 1997 - Workshop for Educators entitled "Earthquakes on the Internet"
conducted at Caltech by John Marquis, Katrin Hafner , Egill Hauksson and Curt Abdouch
