Ground Motion Prediction and Scenario Earthquake Simulations

1. Ground Motion Prediction and Scenario Earthquake Simulations Robert Graves US Geological Survey • Ground Motion Prediction Resources • OpenSHA • CyberShake • Broadband Simulation Platform • WebSims (simulation distribution portal) • Scenario Earthquakes for Engineering Applications (TBI, etc.) • Puente Hills (then and now) • Northern San Andreas • Hayward • Southern San Andreas

2. OpenSHAwww.opensha.org Field et al. (SRL, 2003) • Probabilistic and Deterministic Seismic Hazard Analysis • Open Source • Transparency • Multiple developer tracks • Modular Components (object-oriented framework) • Variety of Earthquake Rupture Forecasts (including UCERF2) • Variety of Ground Motion Prediction Equations (including NGA) • Available Applications • Attenuation Relation Plotter • GMT Map Plotter • Hazard Curve Calculator • Hazard Spectrum Calculator • Magnitude Frequency Distribution • Scenario ShakeMap Generator

3. CyberShake Graves et al. (2010) • Full Waveform Seismic Hazard Model • Replace GMPEs with physics-based simulations • Account for space-time variations in earthquake probabilities • 3D Simulations (T > 2 sec) for all ruptures in UCERF2 • Each rupture has multiple realizations (combinations of hypocenter and slip distribution) • Over 400,000 Rupture Scenarios • Products Include • Database of scenario ruptures • Waveforms and response spectra • OpenSHA Interface • Hazard Curves • Hazard Maps • On-the-fly Probability Updates

4. Broadband Simulation Platform http://scec.usc.edu/research/cme/groups/broadband Callaghan et al. (Poster this meeting) • Computational Platform for Broadband Simulations • Transparency of methods (version control) • Remote access (including non-developers) • Independent testing and validation • Modular framework allows integration of new approaches • Rupture generator for validation and scenario events • High frequency simulation • Low frequency simulation • Combination into broadband • Site response • Products Include • Broadband waveforms • Rupture visualization • Goodness-of-fit comparison

5. WebSimshttp://scec.usc.edu/websims Olsen and Ely (SRL, 2009) • Prototype Ground-Motion Simulation Distribution Portal • Web application providing access to four-dimensional (x,y,z,t) simulation datasets • Extraction of point waveforms and 2D wave field slices • Filtering, plotting and waveform comparison modules • Access to simulation metadata • Currently Available Simulations • ShakeOut kinematic rupture • ShakeOut dynamic ruptures • M5.4 Chino Hills • M7.7.5 Elsinore • M8 So. San Andreas Cui et al. (2010)

6. Puente Hills Graves and Somerville (8NCEE, 2006) • Mw 7.15 Blind Thrust beneath Los Angeles • Relatively rare event, but potentially significant consequences • Initial simulation in 2006, revisited 2010 • Significant reduction in high frequency levels • Low frequency levels basically unchanged

7. Puente Hills Thrust Fault System • Northward dipping, blind thrust directly beneath downtown Los Angeles • 4 large events in last 12,000 years • Mw 6.7 to 7.2+ depending on segmentation and slip • 1987 Mw 5.9 Whittier Narrows EQ after Shaw et al., BSSA, 2002; Dolan et al., Science, 2003

8. South North • Directivity • Buried thrust rupture • Hanging wall • Basin response • Dense Urbanization James Dolan (USC), John Shaw (Harvard)

10. Broadband Simulation Refinements from 2006 to 2010 • Broadband Site Amplification Factors • Rupture Evolution Characterization

11. Broadband Site Amplification Factors 2006: Based on Borcherdt (1994) - weak non-linearity 2010: Based on Campbell-Bozorgnia (2008) - stronger non-linearity Significant reduction in high frequency ground motion levels

12. Rupture Evolution Characterization 2006: Weak timing perturbations 2010: Strong timing perturbations Significant reduction in rupture coherence

13. Ground Motion Maps: PGA

14. Ground Motion Maps: PGV

15. Ground Motion Maps: SA 5 sec

16. Northern San Andreas (1906-type) Aagaard et al. (BSSA, 2008) • Ground Motion estimates for Mw 7.8 1906 and hypothetical scenario EQs • Collaborative effort involving multiple modeling groups • 3D USGS Bay Area Seismic Velocity Model • Detailed representation of SAF geometry • 1906 Modeling • Source characterization based on Song et al. (2006) • Simulations within 1 MMI of Boatwright and Bundock (2005) intensities • Scenarios • Stochastic slip with north, central and south hypocenters • Strong directivity in SF region for north and south hypocenters

17. Rupture Characterization

18. 1906 Simulation and GMPE Prediction

19. 1906 Observed and Simulated Intensities Observed Boatwright and Bundock (2005) Simulated

20. Scenario Ruptures: Effect of Hypocenter on MMI North Hypocenter 1906 Hypocenter South Hypocenter

21. Hayward Aagaard et al. (BSSA, 2010) • Multiple rupture scenarios with Mw 6.76 – 7.12 • Collaborative effort involving multiple modeling groups • 3D USGS Bay Area Seismic Velocity Model • Detailed representation of east-Bay fault geometry • Mw 6.76 bilateral HS rupture reasonably consistent with 1868 intensities • Rupture Complexities • Multiple segment ruptures (Rogers Creek, Hayward N & S, Calaveras) • Creeping sections • Simulated motions exhibit strong rupture directivity and basin response effects

22. 1680 Southern San Andreas (ShakeOut) Graves et al. (EQ Spectra, 2010) • Mw 7.8 scenario • Average time between previous events: 150 years (or less) • Rupture characterization requires multi-disciplinary input • Rupture length • Magnitude • Slip distribution • Slip function • Rupture velocity • Hypocenter 1906 Creepingsection 1857

23. 1812 1857 1680 Slip (m) thrusting & folding WGCEP Slip Rates: 20±3 10±3 16±3 22±6 28±7 San Gorgonio Pass SOUTH NORTH Coachella Valley Mojave Static Displacement Characterization Slip Predictable Model: total release of strain accumulated since most recent event  Relatively high static stress drop event

24. Earthquake Rupture Animation

28. Summary • Variety of ground motion prediction resources are currently available or being developed • Simulation capabilities are continually being refined and updated with new information • Rupture characterization • High frequency (f > 0.5 Hz) ground-motion modeling • Feedback and interaction with engineering community is a vital component of this process