1. Preliminary PEER-NGA Ground Motion Model
Brian Chiou and Robert Youngs
PEER-NGA Workshop
April 12, 2005

2. Data Selection Excluded earthquakes Excluded records
Gorda plate earthquakes – oceanic crust
Subduction zone earthquakes
Poorly known overseas earthquakes
Northwest China earthquakes
Earthquakes recorded by SMART1 array
Aftershocks (used only in site effects analysis)
Excluded records
In basements
In large structures
On dam abutment

3. Modeling Concepts Source scaling Distance scaling Magnitude (M, M2.5 )
No aspect ratio
Depth (depth to the top of rupture)
Style of faulting (SS+NM vs. RV)
Aftershocks not used
Distance scaling
Closest distance to fault
Effect of Q for large distances
Break in slope at about 60 km
Hanging wall effects, function of fault dip angle

4. Modeling Concepts (cont’d)
Site Effects
Function of VS30 (will examine effect using categories)
Nonlinear site amplification (using empirical data guided by modeling results)
Depth to VS ~ 1 km/s

5. Model Form
Reference site motion (Vs=1130m/sec)
Site effects yr ys

6. a
ln(yr) c b
Amplification relative to Vs=1130 m/sec

7. PGA Comparison to Site Response Analysis with EPRI Soil Property Model
Analysis (EPRI Soil)
Regression

8. Comparison to Site Response Analysis with Peninsula Range Soil Property Model
PGA
Site Response
Analysis (Peninsula Rage Soil)

9. Comparison to Site Response Analysis with EPRI Soil Property Model
T=1 Sec
Site Response
Analysis (EPRI)
Regression

10. Comparison to Site Response Analysis with Peninsula Range Soil Property Model
PGA

11. Soft Rock, Strike Slip and Reverse PGA

12. Strike Slip Soft Rock and Soil PGA

13. Strike Slip Soil PGA and 1 Hz PSA

14. Inter-event Residuals
Magnitude
Distance

15. PGA Intra-event Residuals
Magnitude
Distance

16. 1 Hz PSA Intra-event Residuals
Magnitude
Distance

17. T=3Sec

18. T=3Sec

19. Dip Slip Earthquakes, Records on HW/FW
T=3Sec

20. T=3Sec