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Application of empirical Green’s functions for the construction and validation of the GBCVM

Application of empirical Green’s functions for the construction and validation of the GBCVM. Morgan P. Moschetti and Michael H. Ritzwoller Center for Imaging the Earth’s Interior Univ. of Colorado, Boulder Arthur Rodgers and Anders Petersson Lawrence Livermore National Laboratory

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Application of empirical Green’s functions for the construction and validation of the GBCVM

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  1. Application of empirical Green’s functions for the construction and validation of the GBCVM Morgan P. Moschetti and Michael H. Ritzwoller Center for Imaging the Earth’s Interior Univ. of Colorado, Boulder Arthur Rodgers and Anders Petersson Lawrence Livermore National Laboratory GBCVM Workshop, UNR January 14, 2008

  2. (Weaver, 2005) Overview • Ambient noise processing for EGFs • Dispersion measurements for surface wave tomography • 3-D inversion - shear wave velocity values • Comparison of EGFs and synthetics from the USGS Bay Area 3-D velocity model. • Application to GBCVM

  3. Station 109C Broadband Station Y12C 4 – 10 sec Normalized velocity 10 – 20 sec 16 Month Stack 20 – 35 sec time (s) Distance: 258 km 0 100 200 250 time (s) Ambient Noise Processing for empirical Green’s functions

  4. U (km/s) period (s) Rayleigh group velocities

  5. Rayleigh Wave Group Velocity, 8-sec

  6. Rayleigh Wave Phase Velocity Maps • 477 stations (USArray TA and regional networks) – 0.5 degree grid • > 100,000 inter-station paths • Ability to improve local resolution with higher density arrays • http://ciei.colorado.edu/~morganm

  7. Period (s) c (km/s), Rayleigh c (km/s), Love Rayleigh wave phase velocity maps Love wave phase velocity maps Period (s) Local Dispersion curves for inversion

  8. c (km/s), Rayleigh c (km/s), Love Period (s) Neighbourhood Algorithm to define an ensemble of acceptable models

  9. Crustal thickness (km) Crustal thickness estimates

  10. Upper and middle crust slices

  11. Lower crust and upper mantle slices

  12. BKS-MNRC BKS-BNLO red: EGF green: synthetic Rayleigh waveform comparisons – validation of the USGS Bay Area 3-D Velocity Model (from collaboration with Rodgers and Petersson, LLNL.)

  13. Inter-station paths with good measurements • USGS Bay Area 3-D model – two domains • 130 common paths (EGF/synthetics) • EGFs limited by stations, synthetics limited by model.

  14. BKS - MNRC Group velocities Phase velocities Velocity (km/s) period (s) period (s) BKS - BNLO Group velocities Phase velocities Velocity (km/s) period (s) period (s) Rayleigh wave dispersion measurements

  15. Rayleigh wave 10-sec difference map Group velocity Phase velocity

  16. Conclusions and Future Work • Empirical Green’s functions within and across Nevada for comparison and inversion. • Shear-wave velocities across Nevada for background values and model/inversion constraint. • Comparison of EGF and synthetic waveforms allows for validation and assimilation of models. • Improved data coverage from higher density arrays.

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