HR: 11:35h
AN: S32A-06    [Abstracts]
TI: Development of Automated Signal and Meta-data Quality Assessment at the USGS ANSS NOC
AU: * McNamara, D
EM: mcnamara@usgs.gov
AF: USGS Geologica Hazards Team, 1711 Illinois St., Golden, CO 80401, United States
AU: Buland, R
EM: buland@usgs.gov
AF: USGS Geologica Hazards Team, 1711 Illinois St., Golden, CO 80401, United States
AU: Boaz, R
EM: riboaz@xs4all.nl
AF: Boaz Consulting, Korte Leidsedwarsstraat 105/C, 1017PX Amsterdam, Netherlands
AU: Benz, H
EM: benz@usgs.gov
AF: USGS Geologica Hazards Team, 1711 Illinois St., Golden, CO 80401, United States
AU: Gee, L
EM: lgee@usgs.gov
AF: USGS Geologica Hazards Team, 1711 Illinois St., Golden, CO 80401, United States
AU: Leith, W
EM: wleith@usgs.gov
AF: USGS Geologica Hazards Team, 1711 Illinois St., Golden, CO 80401, United States
AB: Real-time earthquake processing systems at the Advanced National Seismic System (ANSS) National Operations Center (NOC) rely on high-quality broadband seismic data to compute accurate earthquake locations, moment-tensor solutions, finite-fault models, Shakemaps and impact assessments. The NEIC receives real- time seismic data from the ANSS backbone, the Global Seismographic Network, ANSS regional network operators, foreign regional and national networks, the tsunami warning centers and the International Monitoring System. For many contributed stations, calibration information is not well known. In addition, equipment upgrades or changes may occur, making it difficult to maintain accurate metadata. The high-degree of real-time integration of seismic data necessitates the development of automated QC tools and procedures that identify changes in instrument response, quality of waveforms and other systematic changes in station performance that might affect NEIC computations and products. We present new tools and methods that will allow NEIC and other network operations to evaluate seismic station performance and characteristics both in the time and frequency domain using probability density functions (PDF) of power spectral densities (PSD) (McNamara and Buland, 2004). The method involves determining station standard noise conditions and characterizing deviations from the standard using the probabilistic distribution hourly PSDs. We define the standard station noise conditions to lie within the 10th and 90th percentile of the PSD distribution. The computed PSDs are stored in a database, allowing a user to access specific time periods of PSDs (PDF subsets) and time series segments through a client-interface or programmatic database calls. This allows the user to visually define the spectral characteristics of known system transients. In order to identify instrument response changes or systems transients we compare short-term spectral envelopes (1 hour to 1 day) against the long-term station noise envelopes. Operationally, the software is useful for characterizing the current and past performance of existing broadband stations, for conducting tests on potential new seismic station locations, for detecting problems with the recording system or sensors, and for evaluating the overall quality of data and meta-data. Currently, PQLX is operational at the USGS for station performance monitoring and metadata quality control.
DE: 7200 SEISMOLOGY
DE: 7219 Seismic monitoring and test-ban treaty verification
DE: 7294 Seismic instruments and networks (0935, 3025)
SC: Seismology [S]
MN: 2007 Joint Assembly