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Discussion Points

Discussion Points. Existing data Sets Tectonics Simulations Analogs Data modeling Data processing. Ground Motion Parameters. Source Mw, scaling Radiation pattern Propagation Crustal structure, Q, Duration Site. Discussion Points. Existing data Sets Tectonics Simulations Analogs

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Discussion Points

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  1. Discussion Points • Existing data Sets • Tectonics • Simulations • Analogs • Data modeling • Data processing

  2. Ground Motion Parameters • Source • Mw, scaling • Radiation pattern • Propagation • Crustal structure, Q, Duration • Site

  3. Discussion Points • Existing data Sets • Tectonics • Simulations • Analogs • Data modeling • Data processing

  4. Data Sets • SE Canada • Assembled 12/2008 • Can be rapidly reprocessed • Central US • Parametric data from 1982 – present from 3 networks: SLU/CERI (1982-1990), PANDA, CERI (2000's)

  5. New Madrid/Central U.S. • Merge of 3 data sets • 1982-1991 – regional network • 1 Hz sensor, vertical • 1990-1991 – PANDA • 4.5 Hz sensor 3 component • 2002-2005 – CERI (and SLU ) • 4.5 Hz sensor – 3 component • Broadband – 3 component • (no gain ranged used) • Can be augmented

  6. 1982-1991 Epicenters (left), stations (right)

  7. 2000-2002 Epicenters (left), stations (right)

  8. Status • Canada • Data sets on-line • Can be reconstructed from GSC autodrm • New Madrid • 1982-1991 tabular data of Fourier velocity spectra and peak filtered velocity, largest EQ's are 1990 and 1991 • 2002-2006 – waveforms on hand • Can be augmented

  9. Source Mechanics and Mw • Affects geometrical spreading at short distance (modeling) • Spatial coherency in North America

  10. Characteristic faulting for North America • Blue – thrust • Green – strike slip • Red - normal

  11. www.eas.slu.edu/Earthquake_Center/MECH.NA • Blue – thrust • Green – strike slip • Red – normal • Spatial coherency may demand different scaling relations

  12. Discussion Points • Existing data Sets • Tectonics • Simulations • Analogs • Data modeling • Data processing

  13. Unpublished work (2003) • Theoretical study at 1 Hz – motions are somewhat coherent • Given insight if can be verified with real data • Next slides show some aspects of the study • Can easily be recomputed • Purpose to detail SLU processing and interpretation methodolody

  14. Crustal models • Test effects of • Crustal thickness • Deep sediments • Upper crustal gradients

  15. Effect of Moho Depth • Deviation from 1/R spreading • Moho bump depends on crustal thickness • Compare filtered velocity and Fourier velocity • Compare SS, 45DS and mixed population

  16. Deep sediment effect • Large differences between components are reduced, especially for 45 DS mechanism

  17. Analogs to Augment Data Set • Korea • Source – AB95 • Radiation – Strike Slip • Propagation – 30 km thick crust, lower Q • Site – weathered Archean • Data available by FTP • Response known • Site characterization, perhaps • Cooperation with KMA, KINS, other agencies

  18. Source Mechanics • 32 MT solutions • Mw 3.2 - 4.7 • Mostly strike slip • H < 15 (upper crust) • Excellent modern digital network (24 bit, STS-2, Episensor)

  19. 20070102115645Mw=4.55, H=9km

  20. Attenuation • Observed (color) and predicted attenuation for narrow-bandpass filtered ground velocity • Residual of fit

  21. Korea • Strike slip sources • Good network • Focus on aspects of source, short distance attenuation • www.eas.slu.edu/Earthquake_Center/ • MECH.KR

  22. Australia • Focus on MT solutions, structure • www.eas.slu.edu/Earthquake_Center/ • MECH.AU • Feasibility study

  23. Earthquakes • Date ML Mw 20090131084703 4.6 3.78 Beacon, WA 20090305125351 4.5 4.05 Beacon, WA 20090305125351 4.2 4.45 SE Australia 20090318052818 4.2 4.42 SE Australia All are thrust H < 6 km Long period wave propagation to 1000 km similar to ENA Sparse distributution of broadband stations

  24. Australia • Sparse station distribution • Can get Mw • Study sequences to derive source spectrum scaling before use • Thrust mechanisms which will permit augmentation of SE Canada, NEUS data set

  25. Ground Motion Parameters • Source • Mw, scaling • Radiation pattern • Propagation • Crustal structure, Q, Duration • Site

  26. Discussion Points • Existing data Sets • Tectonics • Simulations • Analogs • Data modeling • Data processing

  27. Decisions to be made • Use of stochastic modeling • If done, what should be collected to constrain the modeling, e.g., PGA, PGV, Fourier spectra and/or narrow bandpass filtered ground velocity • Preparation of parametric data • If SA, then how to do this given limitations of existing data sets, e.g., 20 Hz, 40 Hz and some 100 Hz sampling

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