Four projects were funded in the Seismology in 2003-2004. These were: (1) the Southern California Earthquake Data Center for, (2) groups assembling waveform products and earthquake catalogs (several projects), (3) the Borehole Seismometer Network, and (4) the Portable Broadband Instrument Center (PBIC). All these projects furthered the aims of the Southern California Earthquake Center and most are continuing in the coming years.

Southern California Earthquake Data Center (SCEDC)

The Archive (as of Sept. 13, 2004) has assembled 3.532 TB of waveform data. The SCEDC database contains 235,647,421 rows and 519,598 earthquakes (1932–present). In the first 6 months of 2004 the SCEDC exported 29.6 million waveforms (913 GB) via STP (i.e., 1.9 waveforms every second), archived 7,929 new events, and archived 2,010,709 seismograms.

The SCEDC has created a new website, with improved navigation (fewer mouse clicks needed) and better documentation, which has generated more web traffic.

SCEDC's Seismic Transfer Program (STP) has been improved. Windows command-line and GUI clients are now available and XML output format may be generated for phase and event data. Two new commands are now available: ‘altloc’ to access to alternate location catalogs and ‘coda’ to access to coda measurements. A Programmatic Interface has been created that allows user-written programs to call data directly from the STP server, instead of having to download data beforehand. An application of this is the SAC2000 STP module, which allows the user to pull data into SAC memory using STP commands.

SCEDC has also implemented three critical IRIS products. SeismiQuery is a web-based program that provides users with pre-formatted queries concerning waveform data, instrument response, and channel information using point-and-click or form-based requests. NetDC is a system to enable data to be retrieved by other data centers and help users with “one-stop shopping” for seismic data. DHI (Data Handling Interface) can be thought of as an Application Programming Interface (API) that can be used as a well-specified, standardized interface to any seismic data center.

Station information has been improved at the SCEDC. Dataless SEED Volumes are available for all currently-active SCSN broadband stations. This effort is being expanded to provide a complete station history in the SEED volumes distributed by the SCEDC. Also, a clickable Station Map is available.

Catalogs available at the SCEDC include:

• 1932–present SCSN Searchable Catalog Page
• Pre-compiled ASCII catalog files
• Alternate Location Catalogs: SCEDC added two catalogs (Hauksson et al., 2004; Shearer et al., 2004) that use results from a SCEC-sponsored project that applies waveform cross-correlation to measure precise differential times among nearby events.

Searching tools available at the SCEDC include:

• 4-Point Polygon Catalog Search
• Radius Catalog Search
• Search by Event ID
• Multiple-magnitude Catalog Search
• New output format: XML

Caltech/UCSD Waveform Analysis Projects

Hauksson (Caltech) and Shearer (UCSD) have assembled an on-line database of southern California waveforms (1984 to present) for use in a variety of projects. Waveform cross-correlation of over 300,000 events, each with 100 neighboring events, is now completed for 1984 to 2002 data. The resulting differential times have been used to generate two new catalogs of southern California seismicity, which may be obtained through the SCEDC. One catalog uses the double-difference method (Hauksson et al., 2004), the other uses source-specific station terms and a cluster analysis approach (Shearer et al., 2004). Both reveal more fine scale fault structure than previous catalogs. These efforts will continue with the goal of beginning to integrate cross-correlation methods into standard network processing. In addition, some funding has gone to Waldhauser to begin comparisons with the techniques used for his northern California waveform cross-correlation project.

Hauksson and Shearer have computed P and S spectra for the online waveforms using a multi-taper method and begun analysis to recover t* measurements and source spectra. The t* values are being used for attenuation tomography to produce 3-D crustal Q models. Stacking methods are planned to isolate source spectra and estimate stress drop and radiated energy. These measurements will enable progress on a range of earthquake scaling issues.

Borehole Seismometer Network Activity

The Pinon Flat and Keenwild sensors have been replaced with Hyposensor packages. Bedrock borehole sites are being explored for source physics studies. Connections to ANZA/CISN/NEES through HPWREN wireless network (UCSD/NEES cost share) are being developed.

Primarily, the borehole network was in maintenance mode for 2004. We continued to take advantage of cost sharing with other agencies. The previously funded sites at Rinaldi (LADWP/CISN cost share), Bonds Corner (NSMP/ANSS cost share), and the telemetry at Superstition Mountain (UCSD/ANZA/HPWREN/NEES cost share) were completed.

SCEC/CISN Borehole stations were integrated into the UCSB NEES database and real-time processing software. We developed automated spectral fitting procedures for incorporation into routine processing and developed combined Wavelet/Spectral inversion techniques solving for attenuation and velocity structure (with postdoc and grad students).

2004 PBIC Activities

A major activity of the PBIC was the San Simeon earthquake rapid array mobilization program (RAMP). The deployment was coordinated with the Menlo Park branch of the USGS and Cal State Northridge. 15 stations were deployed for 3 months. Over 2700 events were recorded that associate with the NCDC catalog at just the SCEC/CSUN stations. UCSB now has copies of all portable data. A SCEC summer intern assisted with data processing using the Antelope software package and integrated the USGS and SCEC/CSUN data sets.

Two other projects used PBIC equipment in 2003/2004. Steve Day and Frank Vernon (SDSU/UCSD) recorded receiver functions to delineate crustal structure across the Peninsular Ranges. The equipment was also deployed to quantify wave energy at the shoreline and understand coastline evolution (UCSC, P. Adams, R. Anderson, J. Revenaugh).