1. 11/02/2007PEER-SCEC Simulation Workshop1 NUMERICAL GROUND MOTION SIMULATIONS: ASSUMPTIONS, VERIFICATION AND VALIDATION Earthquake Source Velocity Structure Wave Propagation

2. 11/02/2007PEER-SCEC Simulation Workshop2

3. 11/02/2007PEER-SCEC Simulation Workshop3  Rupture time derived from simple scaling formula  Coarse slip distribution and hypocenter after Hartzell et al. (1996)  Extend to fine-scale sampling using K -2 filter (e.g. Somerville et al., 1999) Creating a Rupture Model: Northridge Earthquake

4. 11/02/2007PEER-SCEC Simulation Workshop4 TpTp TrTr A h Slip Velocity Function

5. 11/02/2007PEER-SCEC Simulation Workshop5

6. 11/02/2007PEER-SCEC Simulation Workshop6 Rupture Description Issues Currently kinematic with dynamic guidance/constraints Fully dynamic descriptions are expensive and underlying physics is not completely understood

7. 11/02/2007PEER-SCEC Simulation Workshop7 Complex 3D Basin Geology SCEC CVM

8. 11/02/2007PEER-SCEC Simulation Workshop8 Solution (approximate): Average media parameters over grid cell volume (effective media parameters) Harmonic averaging of Lame parameters (λ and µ) Arithmetic averaging of density (ρ) Spatial Aliasing for Grid Based Models

9. 11/02/2007PEER-SCEC Simulation Workshop9 Velocity Structure Issues Different grid-based methods (FEM, SEM, FDM) will “see” slightly different velocity structures. Our knowledge of the true velocity structure is not complete: the models will evolve.

10. 11/02/2007PEER-SCEC Simulation Workshop10 Verification / Validation of Simulation Methodologies Verification =Do the codes / methods perform as expected? (theoretical models) Validation =How well does the method / model predict natural phenomena? (reproduce past observations)

11. 11/02/2007PEER-SCEC Simulation Workshop11 Verification Example

12. 11/02/2007PEER-SCEC Simulation Workshop12

13. 11/02/2007PEER-SCEC Simulation Workshop13 Validation Example: 1994 Northridge EQ buried thrust, strong up- dip directivity near-fault strong motion recordings at 69 sites deep sediment-filled basins

14. 11/02/2007PEER-SCEC Simulation Workshop14 Recorded / Simulated Ground Velocity pulse-like near fault motions extended duration basin motions General waveform character is matched well-

15. 11/02/2007PEER-SCEC Simulation Workshop15 Recorded / Simulated PGA and PGV at 69 Sites

16. 11/02/2007PEER-SCEC Simulation Workshop16

17. 11/02/2007PEER-SCEC Simulation Workshop17

18. 11/02/2007PEER-SCEC Simulation Workshop18

19. 11/02/2007PEER-SCEC Simulation Workshop19