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High-Performance Computing (HPC) IS Transforming Seismology. TeraShake 1 (Olsen et al. 2006 ) 10 12 flops. Southern San Andreas Earthquake M 7.7, scaled Denali slip SCEC CVM3 (600 km x 300 km x 80 km) 3000 x 1500 x 400 = 1.8 G nodes (200 m) 20,000 time steps (0.01 s) 19,000 SU per run
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TeraShake 1 (Olsen et al. 2006) 1012 flops • Southern San Andreas Earthquake • M 7.7, scaled Denali slip • SCEC CVM3 (600 km x 300 km x 80 km) • 3000 x 1500 x 400 = 1.8 G nodes (200 m) • 20,000 time steps (0.01 s) • 19,000 SU per run • 47 TB of simulation data (150,000 files) per run
Data Synthetic Blue: data Red: synthetic 16 Jun 2005, ML4.9, Yucaipa earthquake
HPC makes seismic wave propagation simulations more realistic and more accurate, opens up the possibility for physics-based, deterministic, seismic hazard analysis. Let’s watch a video made by SCEC.
Two Problem Areas • Develop simulation capability for physics-based seismic hazard and risk analysis • TeraShake platform • CyberShake project 2. Improve physical models for SHA - Inversion of large data sets for Unified Structural Representation AWM: Anelastic Wave Model FSM: Fault-system Model RDM: Rupture Dynamics Model SRM: Site-response Model SCEC computational pathways
Realistic 3D Earth Structure Model (CVM) + High-Performance Computing (HPC) = CyberShake
Receiver Green Tensor (RGT) • Obtain Green tensors from a receiver to all grid points by finite difference simulations (3 runs for 3 orthogonal forces at receiver). 3D Earth Structural Model • Reciprocity states that the Green tensors from all the grid points to the receiver is the transpose of the RGT obtained above. • Synthetic seismograms due to an arbitrary point source s at receiver rand their gradients with respect to source locations can be retrieved from the RGT database.
(l, m, n+1) (l, m-1, n) (l, m, n) (l-1, m, n) (l+1, m, n) rS h (l, m+1, n) (l, m, n-1) Confirm Reciprocity Yorba Linda Earthquake to basin station BRE Numerical differentiation to get receiver strain Green tensor Red dash line: synthetics from RGT and reciprocity Blue solid line: synthetics from forward wave propagation
Physics-based Seismic Hazard Analysis (CyberShake) Callaghan et al. (2006)
Red: empirical ground motion model (Abrahamson & Silva 1997) Black: CyberShake (Callaghan 2006)
Two Problem Areas • Develop simulation capability for physics-based seismic hazard and risk analysis • TeraShake platform • CyberShake project 2. Improve physical models for SHA - Inversion of large data sets for Unified Structural Representation AWM: Anelastic Wave Model FSM: Fault-system Model RDM: Rupture Dynamics Model SRM: Site-response Model SCEC computational pathways
Seismic Source Parameter Inversion Isotropic Point Source (IPS) Centroid Moment Tensor (CMT) Finite Moment Tensor (FMT) Fault Slip Distribution (FSD) Number of parameters (5) (8-10) (13-20) (>100) 1 2 3 4 5 6 7 8 Magnitude
Rapid CMT Inversion Using Waveforms computed in a 3D Earth Structural Model Numerical tests to verify inversion algorithm Waveform inversion using 3D RGT synthetics .vs. first-motion focal mechanisms
Yorba Linda Cluster Fontana Trend A new left-lateral fault?
Fréchet Kernel for Full-wave Tomography Born Approximation: Born Kernels
Receiver Green Tensor Data functional: Seismogram perturbation kernel: Fréchet kernel:
F3DT for Southern California (TERA3D) • Target frequency: 1.0 Hz for body-waves and 0.5 Hz for surface waves • Starting model: 3D SCEC CVM4 • Grid-spacing 200m, spatial grid points 1871M • 150 stations, 200 earthquakes, 650 simulations, 5.2M CPU-Hrs • Octree-based data compression, 895TB storage