1. Computer Programs in Seismology Robert B. Herrmann Saint Louis University rbh@eas.slu.edu http://www.eas.slu.edu/ Tutorials: ftp://ftp.eas.slu.edu/pub/rbh/CPS330.TUT

2. Organization Introduction to Computer Programs in Seismology CPS installation Exercises - Part I –Surface waves - Group velocity –Surface waves - Phase velocity Lunch Insight on seismic hazard estimates from synthetics Exercises - Part II –Joint inversion of receiver functions/dispersion –Working with SEED data sets –Shallow Exploration Summary

3. History 1971-1974 - Surface Wave Analysis 1980’s- Synthetic Seismogram 1996- New paradigm – common file formats 2002- Source inversion 2004- gsac

4. Version 3.30 What’s New? Platform support gsac Upgrade to waveform inversion Port of rdseed, evalresp

5. Version 3.30 Platform Support UNIX (Solaris SPARC/PC, OSF) LINUX MacOSX Windows –Cygwin (100%)

6. Computer Programs in Seismology

7. GSAC Basic SAC compatibility for trace manipulation (19500 lines of C and CALPLOT graphics; 1990 FORTRAN sac > 120,000 lines) Use MATLAB for other graphics UNIX/LINUX/ MacOSX/ Windows (Cygwin 100%) Open source

8. Implication Anyone can now do modern seismology, even with PC running windows, often using FREE compilers and support software Anyone!!! Free!!! Open!!!

9. Uses of CPS 3.30 Source parameter determination Inter-station Green’s functions Synthetics Determination of shallow velocity structure

10. gsac Mar 2004, start April 2004, trace interaction Dec 2004, released Jan 2004, updates base on user suggestion Sep 2005, gsac refraction/reflection module

11. January 2005 Improvements: –plot, plotpk - low level plot routines changed to let qdp decimation be controlled by screen resolution –plot, plotpk - low level plot routines changed to reduce number of non- drawing penup moves –prs (plotrecordsection) - low level plot routines changed to reduce number of non-drawing penup moves –cut, xlim - now also take GMT 2004 002 01 02 03 445 and CAL 2004 01 02 01 02 03 455 to define the time window –GNU readline implemented - the user may use the 4 arrow keys to move around the command line and to view history of commands New commands –reverse - reverse a time series –correlate - cross-correlate time series –sign - one bit sgn() operator –stack - stack traces in memory –whiten - force flat amplitude spectrum –markt - put up velocity tics at 1, 2, 3, 4, 5, 6, 7 and 8 km/sec (note that these values are pre-assigned. The user specification is not yet implemented) –taper - trace taper implemented –fileid

12. Source parameters of US Earthquakes 155 events (15 Du et al, 43 older SLU, remainder new using USNSN/ANSS data Autofeed of waveforms for all m > 3.5 in continental US - do not do California Manual analysis and documentation (1 hour)

13. Focal Mechanisms

14. Classification and Orientation of Maximum Compressive Stress

15. Shallow S-velocity Site characterization of ANSS sites Hazard analysis for St. Louis in particular

16. SLU – Test USGS 03 2004 SLU 03 2005 UMR 01 2005

18. St. Louis Univ., 4-26-04, S-wave timber source, 4.5 Hz horizontal phones, 1.0 ms samp int., 1.5 m phone int. No filters or AGC used for display below. We st Ea st Multipl e? Direct wave? Surfac e wave? 2nd layer refraction Bedrock reflection

19. Model Comparison

20. Observations Surface waves have a resolution within a restricted depth range z min < z < z max Refractions and especially reflections provide strong constraint

21. Walk away 24 channel Hammer source, 4.5 Hz vertical geophones

22. Phase velocity analysis using do_pom

23. Comparison of a surf96 inversion to R. A. Williams Vs from SH refraction/reflection

24. Forward prediction of Rayleigh wave phase velocity from R. W. Williams Vs model

25. Insight Combine refraction and reflection data with surface wave dispersion to define velocity structure

26. Current Effort Complete tutorial –Field experiment organization and documentation –Conversion from SEG2 –Surface-wave analysis –Refraction/reflection analysis (gsac) Done! –Joint inversion –Documentation

27. Challenges Use apparent dispersion – follow Japanese papers to select effective mode Use H/Z ratio from noise test to improve depth resolution Build reflection constraint into inversion or just use Monte Carlo

28. Empirical Green’s Functions by cross-correlation of noise Campillo and Paul Shapiro and Campillo Cross-correlate continuous ground noise recordings. Result is proportional to medium response of a impulsive point source applied at surface (Wappenaar, 2004)

29. Original 1 day segments Convert to 1-bit through sgn() Cross-correlate Stack Analyze using MFT (ftan)

30. Problems In spite of 1-bit, spectral peaks which means that MFT must be tailored and plots

31. Sgn bit stack Whitened stack

32. MFT using sgn stack - HRV-CCM

33. MFT using pre-whitening

34. Application to SLU BB Network

35. 28 pairs Noisy Rayleigh wave pulse Only a few have discernible dispersion from MFT, such at BLO-FVM path

36. GSAC> r [ow]RR.sac [ow]TT.sac [ow]ZZ.sac GSAC> xlim o o 300 GSAC> color rainbow GSAC> p

37. GSAC> whiten freqlimits 0.005 0.01 0.25 1 absolute GSAC> whiten freqlimits 0.005 0.01 0.25 1 absolute GSAC> p

38. GSAC> lp c 0.2 n 2 GSAC> p

39. GSAC> echo now comparing the vertical GSAC> xlim o 50 o 180 GSAC> r [ow]ZZ.sac GSAC> p overlay on

40. GSAC> whiten GSAC> whiten GSAC> p

41. GSAC> lp GSAC> p

42. KMA Velocity Sensors

43. KWJ-SEO (258 km) GSAC> r kwjbhrseobhr.WSTK kwjThebhtseobht.WSTK kwjbhzseobhz.WSTK GSAC> hp c 0.1 n 2 p 2 GSAC> lp c 1 n 2 p 2

44. Rayleigh-wave group velocity

45. Observations Do not understand circumstances for success of failure of technique to get dispersion – sensors? path? Getting dispersion requires ad hoc filtering Perhaps value is to use empirical Green’s functions as test data for 3-D simulations Prefer whitened to 1-bit stack

46. Version 3.35 Transverse Isotropy (?) –surface wave modeling –surface wave inversion Shallow S-wave velocity determination –SPAC, ESAC (?) –Joint inversion of refraction survey dispersion and first arrivals

47. The BOOK 300 pages typeset so far

54. Computer Programs in Seismology 1975 - v 1.0 - documentation of programs for dissertation 1980’s - new techniques 1996 - modern set –Easier to use, different paradigm –Tutorials (200 pages each) 2005 - very good research package

55. Computer Programs in Seismology 3.30 Skill Open Source Target –Students –Researchers Platforms –Solaris (SPARC), LINUX, MacOS-X, Windows (CYGWIN) Documentation!!! (needs more)

56. Computer Programs in Seismology

57. Version 3.30 UNIX LINUX MacOSX Windows –Cygwin (100%) (free)

58. What is new 3.30 Modified wvfgrd96 to permit time shifts Minor changes in fmplot and other routines Integrated location program Routinely used for source mechanism studies in US and Korea and

59. GSAC Basic SAC compatibility for trace manipulation (19500 lines of C +CALPLOT graphics; 1990 FORTRAN sac > 120,000 lines) Use MATLAB for other graphics UNIX/LINUX/ MacOSX/ Windows (Cygwin 100%) Open source

60. Goal Simple code, simple use Distributable Generally compatible with SAC2000 Tool for students

61. Differences Tutorials Help indicates abbreviated syntax Subset of essential commands implemented Better –color, windowing –plot metafile

62. –Rotate, rotate3 –plotrecordsection or prs –uses externally created evalresp afile and pfile –suited to shell script –glob (wild cards) –history –readline editing Easily GUI’fied Trivial to extend

67. CPS 3.30 Complete integrated package for regional wave modeling Useful for initial data processing in the field Data inversion requires more experience and Earth constraints

68. Version 3.35 Transverse Isotropy –surface wave modeling –surface wave inversion Shallow S-wave velocity determination –SPAC, ESAC –Joint inversion of refraction survey dispersion and first arrivals

70. Version 3.40 ?

71. High Frequency Ground Motion Studies Applied in Southern California Southern Great Basin SE Canada Korea Italy (4) Germany Switzerland Yunnan, China Central US Utah/Yellowstone Pacific North West Southern Spain Erzican, Turkey Eastern Turkey Marmara S.F. Bay Area N. California Sicily

72. The BOOK 300 pages typeset so far