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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. - PowerPoint PPT Presentation
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Need for an accurate Reno velocity model to understand
amplification in the Reno Basin
Aasha Pancha
Reno Area BasinANSS stations: installed1989 - 2003
Reno Area BasinAbbott and Louie (2000)
1. M=4.4 12/02/2000
2. M=4.49 06/03/2004
1. M=4.4 12/02/2000
Reno Area BasinAbbott and Louie (2000)
• 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
Velocity Model = MA
0.25 km grid
RFNV
RFMA
SKYF
1. M=4.4 12/02/2000
2. M=4.49 06/03/2004
2. M=4.49 06/03/2004
Earthquake Locations
Spatial Variation
Insignificant correlation with basin depth
Correlation is significant at the 68% confidence level.
Basin Depth vs Travel Time Residuals
Correlation is significant at the 98% confidence level.
Travel time residuals vs Fourier spectral amplification
Correlation is significant at the 90% confidence level.
Correlation with Vs30 and Vs100V
s100
(98
%)
V
s30
(94%
)
Earthquake Locations
Azimuthal dependence
XX X X
X
X
• 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.
RF10/RFNZ
E N Z
SF02
E N Z
RF11/RFMA
E N Z
RF07/SKYF
E N Z
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.
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
1. M=4.4 12/02/2000
0.2 to 0.6 Hz
Reno Area Basin
Abbott and Louie (2000)ANSS stations:1989-2003
Correlation with Vs30 and Vs100V
s100
(98
%)
V
s30
(94%
)
Spectral Amplification
Spectral Amplification
Spectral Amplification
SR
NGA models
Campbell and Bozorognia (thin dashed line);
Choi and Youngs (thin line);
Boore and Atkinson (dashed-dot line)
UULLA