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Seismic Data Quality Control

Seismic Data Quality Control. Rick Benson IRIS DMC. Why Routine Quality Control ?. The sooner problems are detected the sooner they can be fixed Sensor malfunctions, misconfigurations, aging Digitizer & recorder malfunctions Vault problems: tilting, settling, etc

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Seismic Data Quality Control

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  1. Seismic Data Quality Control Rick Benson IRIS DMC Data Management Workshop Kuala Lumpur, Malaysia

  2. Why Routine Quality Control ? The sooner problems are detected the sooner they can be fixed • Sensor malfunctions, misconfigurations, aging • Digitizer & recorder malfunctions • Vault problems: tilting, settling, etc • Cable & connection problems • Telemetry issues • Timing problems • Many, many other potential issues Data Management Workshop Kuala Lumpur, Malaysia

  3. QC at the IRIS-DMC The Challenge: A small number of analysts tasked to perform QC on hundreds of stations and thousands of channels (without routine event review). The Solution: Minimize manual analyst work (obviously) by automating as many measurements and monitoring systems as possible and making manual analysis as efficient as possible. Data Management Workshop Kuala Lumpur, Malaysia

  4. Manual QC at the DMC • Visual review of raw data for selected events and, importantly, selections with no events • Visual review of filtered (e.g. 30-300 seconds) data where sensor problems can sometimes be detected before they are evident in the unfiltered data • Polarity checks using large events and the quadrant method • Check residuals between reviewed phase picks and predicted arrivals for gross time or location errors • Review of measurements and alerts from automated systems • Etc. Data Management Workshop Kuala Lumpur, Malaysia

  5. 0º N out Z out 270º 90º All in phase E out 180º Quick Horizontal Polarity Check The “quadrant method” allows an analyst to perform a rough check of 3-component sensor horizontal polarity. Compare the P wave first motion of a relatively large event between the 3 components to determine back azimuth: Aleutian Island event :: Texas, USA station (BA: ~317°) * Assumes Z component polarity is correct. Data Management Workshop Kuala Lumpur, Malaysia

  6. Automated QC at the DMCQuality Analysis Control Kit(QUACK) • Automated QC measurements for incoming real-time data at the DMC • Tracks a number of simple parameters (signal RMS, mean, gaps, overlaps, etc.) in addition to more complicated analyses (PSD/PDF, STA/LTA) • Generates daily reports, using thresholds to control what information is included in the report in order to reduce the number of issues that need attention Data Management Workshop Kuala Lumpur, Malaysia

  7. Real-time Network Monitoring SeisNetWatch Data Management Workshop Kuala Lumpur, Malaysia

  8. SeisNetWatch Details • Monitors multiple parameters in real-time from a station and combines them with user determined thresholds into an overall station performance • Open-source software available from http://www.isti.com/ SeisNetWatch parameters monitored at the DMC: • Data & feed latency, mass position, clock quality, voltage & temperature • Narrow band dead channel detection (bandpass filter incoming data segments to select ~6 second microseisms and calculate standard deviation) Data Management Workshop Kuala Lumpur, Malaysia

  9. Tracking Signal RMS Data Management Workshop Kuala Lumpur, Malaysia

  10. Daily RMS Indicates Problems Data Management Workshop Kuala Lumpur, Malaysia

  11. Tracking Signal Mean Data Management Workshop Kuala Lumpur, Malaysia

  12. Tracking Data Flow Data Management Workshop Kuala Lumpur, Malaysia

  13. Tracking STA/LTA Values Data Management Workshop Kuala Lumpur, Malaysia

  14. PDF of Power Spectral Density Data Management Workshop Kuala Lumpur, Malaysia

  15. Clickable PDFs to Find Time Dependencies Data Management Workshop Kuala Lumpur, Malaysia

  16. PDF Calculation • Current implementations require Mini-SEED and SEED (RESP) system response information • PDF calculation available in the new PQLX analysis package • An older stand-alone PDF package is available: http://geohazards.cr.usgs.gov/staffweb/mcnamara/Software/PDFSA.html • PDFs calculated daily for real-time data received at the IRIS-DMC, stored in database Data Management Workshop Kuala Lumpur, Malaysia

  17. Tide Analysis • Primary gravitational tides are predictable • Most seismic sensors are not designed for such low frequencies & response information may not address them • Pretty much only a true broadband sensor will record the tides The idea: compare recorded seismic data to predicted gravitational tides • Tests both waveform data (polarity, shape) and metadata (instrument response) Data Management Workshop Kuala Lumpur, Malaysia

  18. Tide Comparison at IU.SAML Data Management Workshop Kuala Lumpur, Malaysia

  19. Tide Comparison at TA.H02A Data Management Workshop Kuala Lumpur, Malaysia

  20. Tide Comparison at PR.ICM Data Management Workshop Kuala Lumpur, Malaysia

  21. Tide Comparison Without Response Information Data Management Workshop Kuala Lumpur, Malaysia

  22. Tide Prediction Software • syntides - Synthetic Earth Gravity Tides (IRIS-DMC) • Output: Mini-SEED, SAC or ASCII tide synthetics • Convolves instrument response (SAC format) • Tide calculation a port of the SPOTL ‘ertid’ program • SPOTL - Some Programs for Ocean-Tide Loading • Output: ASCII text • Includes software to calculate solid earth gravity tide, ocean loading components, etc. • Written by Duncan Agnew, UCSD Data Management Workshop Kuala Lumpur, Malaysia

  23. SEED Metadata Verfication verseed - verifies base SEED data structure and formatting (IRIS-DMC) • Works with full SEED, dataless and Mini-SEED combined with dataless SEED (verseed -a) • Includes multiple levels (1-4) of diagnostic information • Basic metadata verification but not response evaluation • C program that runs on Solaris, Linux and Mac OSX Data Management Workshop Kuala Lumpur, Malaysia

  24. verseed example output Data Management Workshop Kuala Lumpur, Malaysia

  25. Other verseed Examples Data Management Workshop Kuala Lumpur, Malaysia

  26. SEED Response Evaluation evalresp - evaluates system amplitude and phase response using SEED RESP format. C program that runs on Solaris, Linux & Mac OSX. JEvalResp - Java version of evalresp, runs anywhere Java is available. Reads either SEED RESP format or fetches response information from a DHI server. JPlotResp - evaluates and plots system amplitude and phase response using SEED RESP format. Reads either SEED RESP format or fetches response information from a DHI server. Data Management Workshop Kuala Lumpur, Malaysia

  27. JPlotResp Usage Data Management Workshop Kuala Lumpur, Malaysia

  28. JPlotResp Console Data Management Workshop Kuala Lumpur, Malaysia

  29. JPlotResp Output Data Management Workshop Kuala Lumpur, Malaysia

  30. JPlotResp Output Per Stage Data Management Workshop Kuala Lumpur, Malaysia

  31. Other Quality Control Resources • QC Forum collaborative web site: http://www.iris.edu/QCForum • General use QC mailing list: qc-issues@iris.washington.edu • New Manual of Seismological Observatory Practice (NMSOP) from IASPEI: http://www.gfz-potsdam.de/bib/nmsop_formular.html • PQLX data analysis system (waveforms & PDFs): http://geohazards.cr.usgs.gov/staffweb/mcnamara/Software/PQLX.html Data Management Workshop Kuala Lumpur, Malaysia

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