Attenuation models for high f simulations
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Attenuation Models for High-F Simulations. Thomas H. Jordan and Xin Song May 2 nd , 2013. Q Models Used in SCEC Simulations. z = 1 km. z = 1 km. z = 1 km. z = 1 km. Hauksson & Shearer (2006) velocity model (bottom-left) is more similar to CVM-S (top-right) than CVM-H (top-left).

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Attenuation Models for High-F Simulations

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Attenuation models for high f simulations

Attenuation Models for High-F Simulations

Thomas H. Jordan and Xin Song

May 2nd, 2013

Song & Jordan


Q models used in scec simulations

Q Models Used in SCEC Simulations

Song & Jordan


Attenuation models for high f simulations

z = 1 km

z = 1 km

z = 1 km

z = 1 km

Hauksson & Shearer (2006) velocity model (bottom-left) is more similar to CVM-S (top-right) than CVM-H (top-left)

Song & Jordan


Attenuation models for high f simulations

z = 10 km

z = 10 km

z = 10 km

Hauksson & Shearer (2006) velocity model (bottom-left) is more similar to CVM-S (top-right) than CVM-H (top-left)

Song & Jordan


Attenuation models for high f simulations

Qs is NOT linearly related to Vs at 1km depth

z = 1 km

Song & Jordan


Attenuation models for high f simulations

Qs is NOT linearly related to Vs at 10km depth

Song & Jordan


Attenuation models for high f simulations

Song & Jordan


Attenuation models for high f simulations

Qs ≈ Qpat 1km depth

Qp

Qs

Song & Jordan


Attenuation models for high f simulations

Qs > Qpat 10km depth

Qp

Qs

Song & Jordan


Attenuation models for high f simulations

Song & Jordan


Attenuation models for high f simulations

ShakeMap Database

QS ~ f1

QS ~ f1/2

QS ~ f0

Attenuation shows strong frequency dependence: QS~ fγwhere γ > 0.5

Song & Jordan


Attenuation models for high f simulations

ShakeMap Database

QS ~ f1

QS ~ f1/2

QS ~ f0

Attenuation shows strong frequency dependence: QS~ fγwhere γ > 0.5

Song & Jordan


Attenuation models for high f simulations

ShakeMap Database

QS ~ f1

QS ~ f1/2

QS ~ f0

Attenuation shows strong frequency dependence: QS~ fγwhere γ > 0.5

Song & Jordan


Attenuation models for high f simulations

H & S shows lower average VSand VP at shallow depths than either CVM-S or CVM-H.

Song & Jordan


Attenuation models for high f simulations

When corrected to low frequencies using QS ~ f2/3, H & S is in close agreement with QS = 50 VSat depth, but not near the surface (z < 5 km).

Song & Jordan


Attenuation models for high f simulations

QS = 50 VS

Horizontal averages over CyberShake region

Song & Jordan


Conclusions

Conclusions

  • Hauksson & Shearer (2006) velocity modelis more similar to CVM-S than CVM-H over CyberShake region.

  • Qs is NOT linearly related to Vs

  • Qs≥ Qp

  • H & S shows lower average VS and VP at shallow depths than either CVM-S or CVM-H.

  • Attenuation shows strong frequency dependence: QS ~ fγwhere γ > 0.5.

  • When corrected to low frequencies using QS ~ f2/3, H & S is in close agreement with QS = 50 VS at depth, but not near the surface (z < 5 km).

Song & Jordan


Recommended q model

Recommended Q Model

  • Use depth-dependent QS-VSrelationships given in following tables

  • Use QS ~ fγwhere γ = 0.7.

  • Use Qp = 1.9 Qs0.9.

Song & Jordan


Attenuation models for high f simulations

A(z) from H&S CyberShake Averages

(assumes f0 = 4 Hz)

Song & Jordan


Attenuation models for high f simulations

A(z) from H&S CyberShake Averages

(corrected to f = 0.5 Hz assuming QS ~ f0.7)

Song & Jordan


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