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Seismic Data Quality Control

Seismic Data Quality Control. Chad Trabant and 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 Chad Trabant and Rick Benson IRIS DMC Data Management Workshop São Paulo, Brasil

  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 São Paulo, Brasil

  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 São Paulo, Brasil

  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 São Paulo, Brasil

  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 São Paulo, Brasil

  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 São Paulo, Brasil

  7. Network Monitoring at the DMCSeisNetWatch Data Management Workshop São Paulo, Brasil

  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 São Paulo, Brasil

  9. Tracking Signal RMS Data Management Workshop São Paulo, Brasil

  10. Daily RMS Indicates Problems Data Management Workshop São Paulo, Brasil

  11. Tracking Signal Mean Data Management Workshop São Paulo, Brasil

  12. Tracking Data Flow Data Management Workshop São Paulo, Brasil

  13. Tracking STA/LTA Values Data Management Workshop São Paulo, Brasil

  14. PDF of Power Spectral Density Data Management Workshop São Paulo, Brasil

  15. Clickable PDFs to Find Time Dependencies Data Management Workshop São Paulo, Brasil

  16. PDF Calculation • Current implementations require Mini-SEED and SEED (RESP) system response information • A 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 • PDF calculation available in the new PQLX analysis package (not yet released) Data Management Workshop São Paulo, Brasil

  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 São Paulo, Brasil

  18. Tide Comparison at IU.SAML Data Management Workshop São Paulo, Brasil

  19. Tide Comparison at TA.H02A Data Management Workshop São Paulo, Brasil

  20. Tide Comparison at PR.ICM Data Management Workshop São Paulo, Brasil

  21. Tide Comparison Without Response Information Data Management Workshop São Paulo, Brasil

  22. Tide Prediction Software • segtides - Solid 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 São Paulo, Brasil

  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 São Paulo, Brasil

  24. verseed example output Data Management Workshop São Paulo, Brasil

  25. Other verseed Examples Data Management Workshop São Paulo, Brasil

  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 São Paulo, Brasil

  27. JPlotResp Usage Data Management Workshop São Paulo, Brasil

  28. JPlotResp Console Data Management Workshop São Paulo, Brasil

  29. JPlotResp Output Data Management Workshop São Paulo, Brasil

  30. JPlotResp Output Per Stage Data Management Workshop São Paulo, Brasil

  31. Other Quality Control Resources • New Manual of Seismological Observatory Practice (NMSOP) from IASPEI: http://www.gfz-potsdam.de/bib/nmsop_formular.html • General use QC mailing list: qc-issues@iris.washington.edu • QC Wiki (coming in the near future): http://seismoqc.blogspot.com/ • PQLII/PQLX/?? (coming in near future): Data viewer and analysis with QC extensions Data Management Workshop São Paulo, Brasil

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