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

11/02/2007PEER-SCEC Simulation Workshop2

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

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

11/02/2007PEER-SCEC Simulation Workshop5

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

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

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

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.

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)

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

11/02/2007PEER-SCEC Simulation Workshop12

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

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-

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

11/02/2007PEER-SCEC Simulation Workshop16

11/02/2007PEER-SCEC Simulation Workshop17

11/02/2007PEER-SCEC Simulation Workshop18

11/02/2007PEER-SCEC Simulation Workshop19