The Broadband CyberShake Platform: Improving Seismic Hazard Analysis using USC HPCC

1. The Broadband CyberShake Platform:Improving Seismic Hazard Analysis using USC HPCC Scott Callaghan Southern California Earthquake Center University of Southern California SC11

2. Probabilistic Seismic Hazard Analysis • Builders ask seismologists: “What will the peak ground motion be at my new building in the next 50 years?” • Seismologists answer this question using Probabilistic Seismic Hazard Analysis (PSHA) • PSHA results used in building codes, insurance • California building codes impact billions of dollars of construction yearly • SCEC uses CyberShake platform to perform PSHA

3. PSHA Reporting • PSHA information is relayed through • Hazard curves (for 1 location) • Hazard maps (for a region) Curve for USC Probability of exceeding 0.1g in 50 yrs

4. PSHA Methodology Pick a location of interest. Define what future earthquakes might happen. Estimate the magnitude and probability for each earthquake, from earthquake rupture forecast (ERF) Determine the shaking caused by each earthquake at the site of interest. Aggregate the shaking levels with the probabilities to produce a hazard curve. Repeat for multiple sites for a hazard map. Typically performed with attenuation relationships. 4

5. CyberShake Computations • Wave propagation simulation • Create 1.5 billion point mesh with material properties • Generate Strain Green Tensors (SGTs) for volume • Describe stresses and strains • Parallel, ~12,000 CPU-hrs

6. Second Phase Computations • Individual earthquake contributions • Use “seismic reciprocity” to simulate seismograms for each of 400,000 earthquakes • Calculate peak shaking, combine for hazard curve • Loosely-coupled, short-running serial jobs

7. High Frequencies • CyberShake calculated seismograms up to 0.5 Hz • Higher frequencies influence shorter buildings • 1-story building ~ 10 Hz • Higher frequency calculations are more intensive • 2x frequency = 16x computational effort • Instead, use stochastic high frequency approach • Already in SCEC Broadband Platform • Use to compute ground motion 0.5-10 Hz • Created Broadband CyberShake • Ran at USC HPCC

8. Computational Requirements (for 1 site) SGT Creation Post Processing

9. Scientific Workflow Tools • Pegasus • Create abstract workflow description (DAX) • Logical names, dependencies • Plan workflow for site-specific execution (DAG) • Logical names resolved • Adds stage-in and stage-out of data • Condor • Workflow submitted to DAGMan • Manages workflow execution on remote resources • Globus • Sends jobs across the grid • GridFTP for fast file transfer

10. Other CyberShake changes • New rupture realizations • More complexity • Less coherence Hazard curves with previous (open circle) and new (closed circle) ruptures Plots of slip for previous (top) and new (bottom) ruptures

11. Multiple Velocity Models • CyberShake now supports multiple velocity models CVM-H minus CVM-S4, depth 0.0m CVM-H 11.2 (red) vs CVM-S4 (blue)

12. Broadband results Currently calculating PBR and seismic stations for validation 710-90 interchange, 0.1 s SA Perris precariously balanced rock,1 s SA

13. Thanks!