Preliminary PEER-NGAGround Motion Model

Brian Chiou and Robert Youngs

PEER-NGA Workshop 7

December 3, 2004

Data Selection

• Excluded Gorda plate earthquakes – oceanic crust

• Excluded subduction zone earthquakes

• Excluded records in basements

• Excluded records in large structures

• Included dam abutment records

Modeling Concepts

• Source scaling– Magnitude– Aspect Ratio– Depth (focal depth)– Style of faulting

• Distance scaling– Closest distance– Effect of Q for large distances– Hanging Wall (to be examined)

Modeling Concepts (cont’d)

• Site Effects– Function of VS30 (will examine effect of using

categories)– Nonlinear site amplification (using empirical

data guided by modeling results)

– Depth to VS ~ 1 and/or 1.5 km/s

Model Form

• Reference site motion

• Site effects

i

r

z

QRMfHypDARFMfCy

),,(),,,()ln( regionpathtypesource1

jrSrs yDVfyy ),,()ln()ln( 5.130site

Inter-Event Residuals

Intra-event ResidualsPGA Model 1

Intra-event ResidualsPGA Model 2

Intra-event ResidualsSA 1 Hz Model 1

Intra-event ResidualsSA 1 Hz Model 2

Model 1 (magnitude only)PGA on Rock (VS30=600m/s)

Model 2 (magnitude & aspect ratio)PGA on Rock (VS30=600m/s)

Model 1 (magnitude only)1 Hz SA on Rock (VS30=600m/s)

Model 2 (magnitude & aspect ratio)1 Hz SA on Rock (VS30=600m/s)

Model 1 (magnitude only)PGA on Soil (VS30=280m/s)

Model 1 (magnitude only)1Hz SA on Soil (VS30=280m/s)