1. 103/25/04 NGA Workshop Parameterization of Basin Response Based on 3D Simulations by PEER/SCEC 3D Ground Motion Project Team PI: Steven M. Day San Diego State University March 25, 2004

2. 203/25/04 NGA Workshop Simulations Completed –85 different earthquake simulations 10 faults from SCEC Community Fault Model 6 rupture scenarios for each (hypocenter and slip model variations) 10 cross-check simulations (1 per fault) 15 1D reference simulations

3. 303/25/04 NGA Workshop Faults Modeled 1. Sierra Madre (7.0) 2. Santa Monica SW (6.3) 3. Hollywood (6.4) 4. Raymond (6.6) 5. Puente Hills I (6.8) 6. Puente Hills II (6.7) 7. Puente Hills (all) (7.1) 8. Compton (6.9) 9. Newport-Inglewood (6.9) 10. Whittier (6.7)

4. 403/25/04 NGA Workshop Six Rupture Scenarios Per Fault 2 hypocenters –1/4 fault-length from each end –7/10 fault-width down dip 3 slip models –Constructed following Somerville (1999) –Constant rupture velocity (2.8 km/s) –Rise time scaled to empirical formula: Log(T r )=0.5(M w +10.7) + log(2.9x10 -9 )

5. 503/25/04 NGA Workshop Coordination Scheme UCB -LLNLUCSBCMUURS (RG)URS (AP) S. MadreF,R,SC S. Mon.F,RC HollyWF,RC RaymF,RC P.Hills6.8F,RC P.Hills6.7F,RC P.Hills7.1F,R,R,SC CompF,R,SC N-I N.R,SFC Whit N.RFC F = 6 3D scenarios C = single cross-check R = 1D rock reference simulation S = 1D basin-profile simulation

6. 603/25/04 NGA Workshop Output Full time histories 3 velocity components 1600 surface points per simulation Basin and rock sites sampled ~300,000 synthetic time histories and associated metadata in digital library

7. 703/25/04 NGA Workshop Cross-check (cont’d) Sierra Madre Scenario Compares FD and FE codes at 16 sites (N-S component): –FD (UCB/LLNL) red –FE (CMU) green

8. 803/25/04 NGA Workshop Response Spectra Data Set synthetic Sa ordinates (2-10 second period range) source distances local basin depth measures (depths to 1.0, 1.5, 2.5, and 3.5 km/s isosurfaces) Sa files available on web

9. 903/25/04 NGA Workshop 3D÷1D_rock Sa Ratios Frequency (Hz) ln(Sa Ratio) Frequency (Hz)

10. 1003/25/04 NGA Workshop Vertically Incident SH Response ln(Sa Ratio) Frequency (Hz)

11. 1103/25/04 NGA Workshop Basin Depth Effect Curves

12. 1203/25/04 NGA Workshop Curve Fits to Basin Depth Effect ( Separately Optimized at Each Period)

13. 1303/25/04 NGA Workshop Curve Fits to Basin Depth Effect ( 6-parameter model for Depth and Period Dependence)

14. 1403/25/04 NGA Workshop Basin Effect Relative to 1-D Soil (2000 m Depth to Isosurface)

15. 1503/25/04 NGA Workshop 1D Rock Simulations vs A-S Regression Model Period (sec) Underprediction Factor

16. 1603/25/04 NGA Workshop Transfer Function from “Very Hard Rock” to Boore/Joyner “Generic Rock”

17. 1703/25/04 NGA Workshop

18. 1803/25/04 NGA Workshop 1.5 Km/s Isosurface Map

19. 1903/25/04 NGA Workshop 8 Sec Sa Mean Residual Map

20. 2003/25/04 NGA Workshop 5 Sec Sa Mean Residual Map

21. 2103/25/04 NGA Workshop 3 Sec Sa Mean Residual Map

22. 2203/25/04 NGA Workshop RMS Residuals

23. 2303/25/04 NGA Workshop 8 sec Sa RMS Residual Map

24. 2403/25/04 NGA Workshop 5 sec Sa RMS Residual Map

25. 2503/25/04 NGA Workshop 3 sec Sa RMS Residual Map

26. 2603/25/04 NGA Workshop Summary Source-averaged 3D effect is largely captured by basin depth term (depth to 1.5 km/s isosurface) Mean and variance are period-dependent Results almost certainly double-count effects partially represented in “rock” regression equations With ~500 m depth sites (instead of 0 depth) taken as “rock” reference: –absolute amplitudes at long period (5 sec) come into agreement with A-S rock regression (i.e., under-prediction eliminated) –Addition under-prediction at shorter periods probably partly a source effect (which would be removed by our analysis of ratios) –Maximum basin effect reduced to ~2 (@ 2 sec) to ~3 (@ 10 sec)

27. 2703/25/04 NGA Workshop Summary (cont’d) Little or no systematic basin-edge effect in source- averaged residuals Likewise, no clear basin-edge effect in source- averaged standard deviations

28. 2803/25/04 NGA Workshop Directions for Additional Work Analysis of current synthetic data set for –Basin-specific (e.g., L.A., San Fernando, San Gabriel) variations –Event-specific basin effects Simulations for additional regions (e.g., Santa Clara Valley? Imperial Valley? others) to examine transportability of results Push simulations to ~1 Hz