ssic_noisepdfqc_march2005.ppt
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Power Spectral Density (PSD)Probability Density Functions (PDF)
A Seismic Data QC and Network Design Tool
Developers:Dan McNamara, Ray Buland @ ANSS NOCRichard Boaz @ Boaz Consultancy (formerly IRIS PASSCAL)
Others involved:Harold Bolton, Jerry Mayer @ ANSS IDCCTim Ahern , Bruce Weertman @ IRIS DMC
USGS-IRIS Collaborative QC Development Effort
USGS noise PDF algorithm - Summer 2001USGS informal QC PDF - Fall 2001 IRIS DMC Quack RFP - Fall 2002Proposal funded - Spring 2003Programmer hired - Fall 2003DMC QUACK PDF operational - June 2004BSSA Paper published - Aug. 2004USGS Formal QC PDF - Sept. 2004Stand Alone PDF - Oct. 2004
Phase II Development - FY 2005-2006QDAT:database PSDsanalyst GUI
ANSS NOC IDCCAhttp://gldqc/cgi-bin/pdf (ANSS backbone, internal USGS)IRIS DMC (IU, II, UW, NM most global and US regional networks)http://www.iris.washington.edu/servlet/quackquery/IRIS PASSCAL Earthscope USarray
http://www.iris.washington.edu/servlet/quackquery_us/Berkeley Seismic Lab
http://moho.geo.berkeley.edu/seismo/PDF/University Utah Seismogram NetworkORFEUS Taiwan National Seismograph Network
PDF Methods and Explanation websitePhttp://geohazards.cr.usgs.gov/staffweb/mcnamara/PDFweb/Noise_PDFs.html/
PDF Locations
Method: Power Spectral Density Probability Density Functions
Raw waveforms continuously extracted from waveserverIn 1 hour segments, overlapping by 50%.PSD pre-processing:
trend and mean removal10% cos taper applied
No screening for earthquakes, or transients and instrumental glitches such as data gaps, clipping, spikes, mass re-centers or calibration pulses
PSD calculated for each 1 hour segmentWith ASL algorithm for direct comparison to NLNM.
PSD is smoothed by averaging powers overfull octaves in 1/8 octave intervals.Points reduced from 16,385 to 93.
Center points of octave averages shown.
Power Frequency Distribution Histograms
PSDs are accumulated in 1dB power bins from -200 to -50dB.
Distributions are generated for each period in 1/8 octave period intervals.
Histograms vary significantly by period.
- 1s has strong peak and a narrow range of powers.
- bimodal distributions at 10, 100s
-All have sharp low-power floor with higher power tails
Next step:Convert histograms to Probability Density Functions
Individual histograms for each period are converted to PDFs by normalizing each power bin by total number of observations.
Total distribution of powers plotted.Not simply minimum powers.
PSD Probability Density Function for ISCO BHZ
QuickTimeª and aTIFF (Uncompressed) decompressor
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QuickTimeª and aTIFF (Uncompressed) decompressor
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HLID - automobile traffic along a dirt road only 20 meters from station HLID creates a 20-30dB increase in power at about 0.1 sec period (10Hz). This type of cultural noise is observable in the PDFs as a region of low probability at high frequencies (1-10Hz, 0.1-1s).
Body waves occur as low probabily signal in the 1sec range while surface waves are generally higher power at longer periods.
Automatic mass re-centering and calibration pulses show up as low probability occurrences in the PDF.
Artifacts in the Noise Field
Current Noise PDF Uses
Network SOH monitoringDead stationDetection ModelingDesign Planning
Station Quality Site quality Current stationsfuture backboneANSS Rankings
Noise Researchsourceshurricanesambient noise model
Hailey, ID 08/2001-05/2002
McNamara and Buland (2004) BSSA
Realistic view of noise conditions at a station. Not simply lowest levels experienced.
Current Noise PDF Uses
Network SOH monitoringDead stationDetection ModelingDesign Planning
Station Quality Site quality Current stationsfuture backboneANSS Rankings
Noise Researchsourceshurricanesambient noise model
GOTO:
IRIS DMC
http://www.iris.washington.edu/servlet/quackquery/
Earthscope USarray
http://www.iris.washington.edu/servlet/quackquery_us/
Lightning strike hours after Station began operation
Current Noise PDF Uses
Network SOH monitoringDead stationDetection ModelingDesign Planning
Station Quality Site quality Current stationsfuture backboneANSS Rankings
Noise Researchsourceshurricanesambient noise model
Current Noise PDF Uses
Network SOH monitoringDead stationDetection ModelingDesign Planning
Station Quality Site quality Current stationsfuture backboneANSS Rankings
Noise Researchsourceshurricanesambient noise model
Brune minimum Mw Mw
Regional Network Simulation6 stations from NM regional network with well established noise baselines.
Detection threshold lowered in New Madrid region by 0.1-0.3 unitswith addition of NM network.
Regional Station Limitations:- high noise in Cultural noise band (1-10Hz)- PVMO instrumented with Guralp CMG-3esp seismometer (50Hz) and Quanterra Q-380 digitizer at 20sps. Power rolloff at Nyquist~10Hz.
PVMO
Mw
Backbone Stations on Satellite GR4
Backbone stations on Satellite SM5
Detection Maps Used for Prioritization of Maintenance Issues
Mw
ANSS backbone distributed over 2 satellites to protect against total network outage. Simulations demonstrate detection in the event of a satellite failure.
Maintenance decisions could be made based on real-time changes in detection thresholds.
GR4 expected to die within 3 years.
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3km from train 20km from train
Current Noise PDF Uses
Network SOH monitoringDead stationDetection ModelingDesign Planning
Station Quality Site quality Current stationsfuture backboneANSS Rankings
Noise Researchsourceshurricanesambient noise model
Meremonte, M., . D M c N a m a r a , A. Leeds, D. Overturf, J. McMillian, and J. Allen, ANSS backbone station installation and site characterization, EOS Trans. AGU, 85(47), 2004.
Current Noise PDF Uses
Network SOH monitoringDead stationDetection ModelingDesign Planning
Station Quality Site quality Current stationfuture backboneANSS Rankings
Noise Researchsourceshurricanesambient noise model
GSN Standing Committee Report:
An Assessment of Seismic Noise Characteristics for the ANSS Backbone
and Selected Regional Broadband Stations
By D. McNamara, Harley M. Benz and W. Leith
Also
, .M c N a m a r a D E ., H.M. Benz and W. Leith, USGS Open-File Report, in press, 2005.
Current Noise PDF Uses
Network SOH monitoringDead stationDetection ModelingDesign Planning
Station Quality Site quality Current stationfuture backboneANSS Rankings
Noise Researchsourceshurricanesambient noise models
McNamara, D.E., R.P. Buland, R.I. Boaz, B. Weertman, and T. Ahern, Ambient seismic noise, Seis. Res. Lett., in press, 2005.
Plans for future development: QDATDatabase hourly PSDs to allow:
creative selection of data for PDF generationPlayback as a movie (i.e. graphic equalizer)Additional types of visualizations
Regional noise trends diurnal and seasonal variations
Researchnoise sourcesbaselinesauto ID of problem artifacts
Operationsvault designtelemetry performanceautomated problem reporting and notification
QuickTimeª and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Seismometer casing differential motion
Plans for future development: QDATDatabase hourly PSDs to allow:
creative selection of data for PDF generationPlayback as a movie (i.e. graphic equalizer)Additional types of visualizations
Regional noise trends diurnal and seasonal variationsspectograms
Researchnoise sourcesbaselinesauto ID of problem artifacts
Operationsvault designtelemetry performanceautomated problem reporting and notification
Plans for future development: QDATDatabase hourly PSDs to allow:
creative selection of data for PDF generationPlayback as a movie (i.e. graphic equalizer)Additional types of visualizations
Regional noise trends diurnal and seasonal variationsspectograms
Researchnoise sourcesbaselinesauto ID of problem artifacts
Operationsvault designtelemetry performanceautomated problem reporting and notification
QuickTimeª and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Regional Noise Characteristics
Plans for future development: QDATDatabase hourly PSDs to allow:
creative selection of data for PDF generationPlayback as a movie (i.e. graphic equalizer)Additional types of visualizations
Regional noise trends diurnal and seasonal variationsspectograms
Researchnoise sourcesbaselinesauto ID of problem artifacts
Operationsvault designtelemetry performanceautomated problem reporting and notification
6am local time
Noise across all periods increases 10-15dB during the working daywith the exception of the microseism band (~7-8s).
Constructed from 90th percentilecomputed from PDFs binned foreach hour of theday.
Data from Sept 2001 toOct 2004
Short period noise increases during the summer months.Microseism band (~7-8s) noise increases during the fall and winter.
Constructed from 90th percentilecomputed from PDFs binned foreach month of the year.
Data from Sept 2001 toOct 2004
School begins
Plans for future development: QDATDatabase hourly PSDs to allow:
creative selection of data for PDF generationPlayback as a movie (i.e. graphic equalizer)Additional types of visualizations
Regional noise trends diurnal and seasonal variationsspectograms
Researchnoise sourcesbaselinesauto ID of problem artifacts
Operationsvault designtelemetry performanceautomated problem reporting and notification
Plans for future development: QDATDatabase hourly PSDs to allow:
creative selection of data for PDF generationPlayback as a movie (i.e. graphic equalizer)Additional types of visualizations
Regional noise trends diurnal and seasonal variationsspectograms
Researchnoise sourcesbaselinesauto ID of problem artifacts
Operationsvault designtelemetry performanceautomated problem reporting and notification
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