Graves Cyber Shake June2005

CyberShake Project Using 3D Synthetic Seismic Waveforms In Seismic Hazard Analysis: 

CyberShake Project Using 3D Synthetic Seismic Waveforms In Seismic Hazard Analysis

Attenuation Relationship-based Ground Motion Predictions: 

Attenuation Relationship-based Ground Motion Predictions Abrahamson and Silva (1997) Boore et al. (1997) Attenuation Relationships produce significant differences in ground motion prediction

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Intensity-Measure Relationship List of Supported IMTs List of Site-Related Ind. Params IMT, IML(s) Site(s) Rupture Attenuation Relationships Simulation IMRs exceed. prob. computed using a suite of synthetic seismograms Vector IMRs compute joint prob. of exceeding multiple IMTs (Bazzurro andamp; Cornell, 2002) Multi-Site IMRs compute joint prob. of exceeding IML(s) at multiple sites (e.g., Wesson andamp; Perkins, 2002) Various IMR types (subclasses) Gaussian dist. is assumed; mean and std. from various parameters

Ruptures in ERF within 200KM of USC: 

Ruptures in ERF within 200KM of USC Each event needs full rupture description, i.e., slip(x,y,z,t)

CyberShake Computational Elements: 

CyberShake Computational Elements Requires calculation of 100,000+ seismogram for each site. SCEC/CME Grid-based scientific workflow system required to work at this scale. Access to distributed computing resources Large scale file management High performance and high throughput computing. TeraGrid allocation awarded for effort 145K SU (TG-BCS050001N)

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BROADBAND GROUND MOTION SIMULATION FOR THE PUENTE HILLS FAULT after Shaw et al., BSSA, 2002 Unprecedented in scope and scale (66,000 broadband time histories, 0 – 10 Hz) Utilizes many SCEC resources (CFM + CVM + CME + ITR) Ground motion visualization Ground motion maps

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Fault location and geometry from Community Fault Model

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Extend to fine-scale sampling using K-2 filter (e.g. Somerville et al., 1999) Rupture time derived from simple scaling formula Coarse slip distribution and hypocenter initially specified

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Model Region 150 km X 110 km X 45 km 380 X 106 node FD grid (h=125 m) Broadband (0-10 Hz) output at 66,000 sites SCEC Community Velocity Model (3D)

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Animation Goes Here

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Ground Motion Maps PGA PGV 1 sec SA

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THE END

CyberShake Project Elements: 

CyberShake Project Elements Use 3D waveform-based Intensity Measure Relationship to calculate Hazard curves for sites in Los Angeles area. Generate 3D synthetics for required number of ruptures (40,000+ ruptures in Earthquake Rupture Forecast) Use Reciprocity-base waveform approach Allows many ruptures for a single site. Requires conversion from simple source representation (location, magnitude) to full finite-fault ruptures [slip(x,y,z,t)].

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BROADBAND GROUND MOTION SIMULATION FOR A MW 6.7 EARTHQUAKE ON THE PUENTE HILLS FAULT Robert Graves URS Corporation

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after Shaw et al., BSSA, 2002 Three Segment Fault Model

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Comparison of Puente Hills LA Segment and Northridge

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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)

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Model Region 150 km X 110 km X 45 km 380 X 106 node FD grid (h=125 m) Broadband (0-10 Hz) output at 66,000 sites

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Complex 3D Basin Geology (deterministic) Hybrid 1D Rock and 1D Basin Profiles (stochastic) SCEC V2.2b

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Deterministic Methodology (f andlt; 1 Hz)

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Stochastic Methodology (f andgt; 1 Hz)

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Simulation Parameters

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Ground Motion Maps

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Spectral Acceleration Maps

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CONCLUSIONS

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Tp Tr A h Deterministic Slip Velocity Function

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Site Amplification Factors (Borcherdt, 1994) Fv Fa Applied in Fourier domain, although strictly defined for response spectra.

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Broadband Ground Motion Simulation for the Puente Hills Blind Thrust (LA Segment)

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1994 Northridge Mw 6.7 Buried thrust, strong up-dip directivity Near-fault strong motion recordings at 69 sites Deep sediment-filled basins

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Recorded / Simulated Ground Velocity pulse-like near fault motions extended duration basin motions General waveform character is matched well:

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Recorded / Simulated PGA and PGV at 69 Sites Near fault directivity Amplification in NW LA Basin

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Spectral Response Goodness-of-Fit Distance / Site Variability

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Stochastic Sub-fault Source Spectrum (after Frankel, 1995) Factor of C ensures: desired mainshock moment desired mainshock slip risetime result generally insensitive to sub-fault size

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Broadband Ground Motion Simulation for the Puente Hills Blind Thrust after Shaw et al., BSSA, 2002

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Model Region 150 km X 110 km X 45 km 380 X 106 node FD grid (h=125 m) Broadband (0-10 Hz) output at 66,000 sites SCEC Community Velocity Model (3D)

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Complex 3D Basin Geology (deterministic) Hybrid 1D Rock and 1D Basin Profiles (stochastic) SCEC V2.2b