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Need for an accurate Reno velocity model to understand amplification in the Reno Basin

Need for an accurate Reno velocity model to understand amplification in the Reno Basin. Aasha Pancha. Reno Area Basin ANSS stations: installed1989 - 2003. Reno Area Basin Abbott and Louie (2000). 1. M=4.4 12/02/2000. 2. M=4.49 06/03/2004. 1. M=4.4 12/02/2000.

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Need for an accurate Reno velocity model to understand amplification in the Reno Basin

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  1. Need for an accurate Reno velocity model to understand amplification in the Reno Basin Aasha Pancha

  2. Reno Area BasinANSS stations: installed1989 - 2003

  3. Reno Area BasinAbbott and Louie (2000)

  4. 1. M=4.4 12/02/2000 2. M=4.49 06/03/2004

  5. 1. M=4.4 12/02/2000

  6. Reno Area BasinAbbott and Louie (2000)

  7. 1D synthetic Green's functions, computed in a layered elastic solid using the generalized reflection and transmission coefficients (Luco and Apsel, 1983; Zeng & Anderson, 1995). • E3D – fourth order, 3D staggered grid elastic finite difference code (Larsen & Schultz [5]; Larsen & Grieger [6]). • 0.2 to 0.6 Hz frequency band. • Compare these simulations with the observed data

  8. Velocity Model = MA 0.25 km grid

  9. RFNV RFMA SKYF

  10. SKYF RFMA SF02 RFNV

  11. 1. M=4.4 12/02/2000 2. M=4.49 06/03/2004

  12. 2. M=4.49 06/03/2004

  13. Earthquake Locations

  14. Spatial Variation

  15. Insignificant correlation with basin depth Correlation is significant at the 68% confidence level.

  16. Basin Depth vs Travel Time Residuals Correlation is significant at the 98% confidence level.

  17. Travel time residuals vs Fourier spectral amplification Correlation is significant at the 90% confidence level.

  18. Correlation with Vs30 and Vs100 Vs100 (98%) Vs30 (94%)

  19. Earthquake Locations

  20. Azimuthal dependence

  21. X X X X X X

  22. Blue = soil to rock (SR) horizontal spectral ratios. • Red = soil to rock (SRv) spectral ratios of the vertical components of motion. • Black = horizontal to vertical spectral ratios (HVSR) for individual stations. • The black dashed = ratio the SR and SRv mean response spectra.

  23. RF10/RFNZ E N Z

  24. SF02 E N Z

  25. RF11/RFMA E N Z

  26. RF07/SKYF E N Z

  27. Summary • Good agreement is observed between the amplitudes of the data, and that of the 3D simulation. • E3D matches the durations in the data and may anticipate some of the later arrivals. The 1D code does not. • 3D basin effects are important and a 3D model is required to model ground motion within the Reno area basin. • Need for refinement on the velocity and basin structural model.

  28. ID Parameters • Mo = 5.17E+22 dyne-cm Calculated: • Area = 0.894 km • Rise time = 0.69 seconds • Slip = 6.3 cm E3D Parameters • Grid spacing = 0.25 km • 77 by 99 km down to depth of 40 km • Rise time 0.7 seconds  Gaussian STF • to = 0.5 seconds • Depth 11 km • dt = 0.015, t=4800  72 seconds

  29. 1. M=4.4 12/02/2000 0.2 to 0.6 Hz

  30. Reno Area Basin ANSS stations:1989-2003 Abbott and Louie (2000)

  31. Correlation with Vs30 and Vs100 Vs100 (98%) Vs30 (94%)

  32. Spectral Amplification

  33. Spectral Amplification

  34. Spectral Amplification

  35. NGA models Campbell and Bozorognia (thin dashed line); Choi and Youngs (thin line); Boore and Atkinson (dashed-dot line)

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