1. 1 Tools for Seismic Network QC or Other Uses of Computer Programs in Seismology Robert B. Herrmann Saint Louis University INGV 24/06/08

2. 2 Outline Teleseismic and Regional processing requirements Incorrect Dataless Seed Using teleseisms for QC Using local earthquakes for QC Instrument response history Update on Computer Programs in Seismology

3. 3 Background - I I have been working with Harley Benz of the USGS NEIC to develop replacements for –teleseismic body moment tensor inversion to implement –regional moment tensor inversion to standardize the computation of synthetic seismograms Waveform inversion requires high quality, calibrated waveforms

4. 4 Example of a data problem

5. 5 NORTHEASTERN SAKHA, RUSSIA Magnitude 5.9 2008 June 22 23:56:32 UTC Has NEIC CMT: –Strike 108 –Dip 44 –Rake 59 –H 10 –Mw 5.9 Examine waveforms for NM (New Madrid) and NE (New England networks)‏

6. 6 Data GSAC> map global on ray on GSAC> sh map.sh GSAC> convert -trim map.eps map.png

7. 7 Compare observed and predicted ground displacements for the moment tensor solution. Units are meters All signals low pass filtered (function of Mw) to ignore specific source time function FLAG anomalous amplitudes

8. 8 Comparison of P on Vertical

9. 9 Comparison of SV on Radial

10. 10 Comparison of SH on Transverse

11. 11 NM Network OK – problems dues to low frequency noise, not calibration NE Network has BIG problems – amplitudes differ by 10 4 and shapes are wrong

12. 12 Background - II I am the principal investigator for a regional seismic network sponsored by the USGS I must –ensure data flow of calibrated signals to NEIC in real time –archive all waveforms and metadata at IRIS

13. 13 Broadband Instruments

14. 14 Accelerometers

15. 15 Quality Control Laboratory testing before installation Testing of dataless seed Evaluation of real data –teleseisms –local earthquakes

16. 16 Laboratory testing Compare broadband to accelerometer adjacent to each other (3 rd floor [2 piano])‏ –test wiring dataless sensors –compare reduced ground velocity of Z N E channels in 0.5 – 3 Hz band (good S/N for bb and acc channels)‏ –compare long period bb to bedrock station 200 meters away

17. 17 Trillium (40s)‏ Episensor Q330

18. 18 Discovery After reducing to ground motion using evalresp to see effect of FIRs discovered problems with earlier evalresp and assumption of symmetric FIRs when we used asymmetric – consequence was different arrival times for LH BH and HH channels for the resultant ground motion. http://www.eas.slu.edu/Earthquake_Center/NM/INSTRUMENT/

19. 19 Comparison of STS-2/Q380 to CMG5TD ground velocity 0.25 – 2 Hz for local earthquake

20. 20 Dataless seed rdseed -f dateless -R -p –(modified rdseed to get more information)‏ use evalresp to get amplitude/phase response. Emulate step acceleration response use pole-zero to get amplitude response. Emulated step acceleration response Script for easy use http://www.eas.slu.edu/Earthquake_Center/NM/OLIL/OLILindex.html

21. 21

22. 22 Why? Check coordinates, orientations, polarities. Ensure that dataless is compatible with rdseed and evalresp

23. 23 Other tools USGS NEIC –mdget All metadata for Continuous Wave Buffer is loaded from dataless SEED. mdget permits getting orientation/coordinates/station/description –in xml and kml mdget -kml -s MN.......... > mn.kml

24. 24

25. 25 Return to NE network Had gain problem from waveform comparison Examine –IRIS Noise spectra –dataless at IRIS

26. 26 Extremely noisy. Historically this was a good WWSSN site. Why? Examine response!

27. 27 rdseed -f NE.dataless -R -p then GSAC> fg impulse delta 0.01 npts 16384 GSAC> transfer from vel to polezero subtype SAC_PZs_NE_WES_BHZ__2003.231.00.00.00.0000 _99999.9999.24.60.60.99999 GSAC> fft GSAC> bg plt GSAC> psp GSAC> plotnps -F7 -W10 -EPS -K wesbhz.eps GSAC> convert -trim wesbhz.eps wesbhz.png

28. 28 Response looks like 1 Hz seismometer not 30 sec CMG-40T Dataless NOT CORRECT

29. 29 Earthquake Data If one can use waveforms for source inversion, then one can use predicted waveforms to test calibration –Can do this for teleseisms, and for –Regional earthquakes

30. 30 20080303141115 - Orfeus

31. 31 Observed/Predicted Filtered Accelerations Observed (red) and predicted (blue) filtered ground velocities 0.05 – 0.20 Hz (Episensor/Q330) using moment tensor for the earthquake. Differences are due to structure and nodal arrivals.

32. 32 Review Use different techniques to test dataless SEED, e.g., ground motions from various channels, compare to other instruments at same location, compare to synthetics For actual operation, rely on real-time displays Periodically use large teleseisms to test functioning and timing

33. 33 Question How does one ensure that independent accelerometers are functioning correctly if there are no local earthquakes to create a high S/N signal? –If very sensitive, e.g., 0.5g max, then one can see teleseisms (good for gain and timing check)‏ –or can one initiate a calibration signal?

34. 34 Proper network calibration is absolutely of the highest importance. Performance must be continually reviewed Determination of earthquake source parameters is one way to accomplish this.

35. 35 Tutorials * Determination of Receiver Functions * Inversion of Surface-Wave Dispersion and Receiver Functions for Structure * Teleseism Synthetics * Surface-Wave Synthetics and Group Velocity Determination * Surface-Wave Synthetics and Phase Velocity Determination * Phase velocity determination using a seismic network and a real data set New SEP 25, 2007! * SEED - Unpacking to SAC, Deconvolving and Rotating * Cross-correlation of Ground Noise - Example for southeastern Spain * Particle motion plots for focal mechanisms * Synthetic seismograms and site * Instrument response - discussing RESP and polezero formats New OCT 19, 2007! * Synthetics for a Spherical Earth New FEB 06, 2008! * Geometrical Spreading for Teleseism P and S NEW FEB 07, 2008 * Simple Programs to read/write SAC files NEW FEB 12, 2008 * Using Synthetics to Evaluate Station Performance NEW MAR 12, 2008 * Use of hudson96 for high-frequency teleseismic P-wave synthetics NEW MAR 26, 2008

36. 36 If interested, I will document the scripts for plotting the dataless response history for the Tutorial page

37. 37 Changes in Computer Programs in Seismology gsac –ppk pquality –fixed rtr, map, dif, computation of distance, sort, refr, prs –added p1, p2 for backward compatibility –write append suffix prepend prefix –prs true amplitude –prototyped make gsac loadable into shell so that gsac commands would be bash commands

38. 38 Updated rdseed evalresp to –rdseed4.7.5.slu to provide extra output –evalresp-3.2.38.slu to handle extra long FIR's (also to compile cross platform)‏ A extensive effort on Earth flattening by comparing modal superposition and wavenumber integration synthetics to free oscillation synthetics (mineos)‏ Updated travel time routines that are now identical in all codes hudson96 for fast high frequency body wave synthetics

39. 39 Next? Implement and document a complete processing package for shallow Vs determination transverse isotropy for surface-waves (actually derived Wang's dissertation equations)‏