Special Project Highlights (2014- 2015) SCEC Leadership Retreat 1 June 2015

OpenSHA Implementation of UCERF3 Kevin Milner, with others, implemented the UCERF3 time-dependent model in OpenSHA leading to the release of UCERF3 time-dependent model in 2015 [Field - 2015]. OpenSHA, a USGS and SCEC software development project since 2001, was recently approved by USGS for use producing national seismic hazard maps. [Field -2015] Edward H. Field, Glenn P. Biasi, Peter Bird, Timothy E. Dawson, Karen R. Felzer, David D. Jackson, Kaj M. Johnson, Thomas H. Jordan, Christopher Madden, Andrew J. Michael, Kevin R. Milner, Morgan T. Page, Tom Parsons, Peter M. Powers, Bruce E. Shaw, Wayne R. Thatcher, Ray J. Weldon II, and Yuehua Zeng Long‐Term Time‐Dependent Probabilities for the Third Uniform California Earthquake Rupture Forecast (UCERF3), Bulletin of the Seismological Society of America, April 2015, v. 105, p. 511-543, March 10, 2015

Dynamic Rupture at Hazard Scale Simulations Zheqiang Shi, Kim Olsen, and Steve Day used a version of the SORD dynamic rupture software to simulate ruptures on rough faults [Shi - 2013]. These simulations produce ruptures with frequencies up to 10Hz. The group then used the output from these simulations as ruptures for high frequency deterministic ground motion simulations. [Shi - 2013] Shi, Z., and S.M. Day (2013), Rupture dynamics and ground motion from 3-D rough-fault simulations, J. of Geophy. Res.: Solid Earth, Vol, 118, 1-20, doi:10.1002/jgrb.50094.

Improved Physics in Wave Propagation Software Kim Olsen, Jacbob Bielak, and Ricardo Taborda continued to develop deterministic ground motion software that models advanced physics of earthquakes. Both groups have developed versions of their codes that model frequency dependent Q. Daniel Roten has developed code that models plastic yielding [Roten - 2014]. Jacobo’s group has performed simulations for Japan with water-based wave propagation, and simulations using topography [Restrepo - 2014]. [Roten - 2014] Roten, D., K.B. Olsen, S.M. Day, Y. Cui and D. Faeh, Expected seismic shaking in Los Angeles reduced by San Andreas fault zone plasticity, Geophysical Research Letters, 41, No. 8, 2769-2777, doi:10.1002/2014GL059411, 2014. [Restrepo - 2014] Restrepo, D., Bielak, J., (2014) “Virtual topography: A fictitious domain approach for analyzing free-surface irregularities in large-scale earthquake ground motion simulation” International Journal for Numerical Methods in Engineering 11/2014; 100(7). DOI: 10.1002/nme.4756

GPU-Versions of Wave Propagation Software Yifeng Cui and Patrick Small have developed GPU versions of earthquake wave propagation codes for both AWP-ODC and Hercules. The GPU version of the AWP-ODC code is about 4-6x faster than the CPU version [Poyraz - 2014], while the GPU version of the Hercules code is about 2x faster than the CPU version. [Poyraz - 2014] Poyraz, E., Xu, H., Cui, Y. (2014) “Application-specific I/O Optimizations on Petascale Supercomputers,” Procedia Computer Science 12/2014; 29:910-923. DOI:10.1016/j.procs.2014.05.082

Geo-technical Layer Impact on Ground Motion Simulations Ricardo Taborda’s group has done a series of validation studies that evaluate alternative SCEC CVMs at frequencies up to 5Hz. His group has evaluated CVM-S4, CVM-H, and CVM-S4.26 using Chino Hills and La Habra events [Taborda - 2014]. They also have looked at the impact of various GTL implementations, working to identify the one that performs best. [Taborda - 2014] Taborda, R. and Bielak, J. (2014) "Ground-Motion Simulation and Validation of the 2008 Chino Hills, California, earthquake using different velocity models," Bull. Seismol. Bulletin of the Seismological Society of America 08/2014; 104(4):1876-1898. DOI:10.1785/0120130266

Full 3D Tomography Developing 3D Velocity Models En-Jui Lee and Po Chen have created 3D velocity models for Central California. As part of SCEC’s Geoinformatics project, the group is improving these models using full 3D tomographic methods including both observed earthquakes and ambient noise [Lee - 2014]. They have shown significant improvement in how well 3D ground motion simulations fit observed waveforms when results using the improved central California model are compared to results using the starting central California model. [Lee - 2014] En‐Jui Lee, Po Chen, Thomas H. Jordan, Phillip B. Maechling, Marine A.M. Denolle, Gregory C. Beroza (2014) Full-3D Tomography (F3DT) for Crustal Structure in Southern California Based on the Scattering-Integral (SI) and the Adjoint-Wavefield (AW) Methods, Journal of Geophysical Research: Solid Earth 08/2014; 119(8). DOI:10.1002/2014JB011346 ·

Unified Structural Representation Model Development David Gill produced a public release of the Unified Community Velocity Model (UCVM) software, in March 2014, and a public release of the CVM-H velocity model, in January 2015. The most recent UCVM software provides access to CVM-S4.26, includes functionality to add small-scale heterogeneities into output models, and provides an improved installation approach. The CVM-H release provides access to the CVM-H discussed in the 2015 USR publication [Shaw - 2015]. [Shaw - 2015] John H. Shaw, Andreas Plesch, Carl Tape, M. Peter Suess, Thomas H. Jordan, Geoffrey Ely, Egill Hauksson, Jeroen Tromp, Toshiro Tanimoto, Robert Graves, Kim Olsen, Craig Nicholson, Philip J. Maechling, Carlos Rivero, Peter Lovely, Charles M. Brankman, Jason Munster (2015), Unified Structural Representation of the southern California crust and upper mantle, Earth and Planetary Science Letters 04/2015; 415. DOI:10.1016/j.epsl.2015.01.016

SCEC Broadband Platform Development Fabio Silva has produced two public releases of the SCEC Broadband Platform in March 2014 [Maechling - 2015] and March 2015. The released software was used in two scientific and engineering evaluations including the Southwest US Ground Motion Characterization SSHAC Level 3 Study and the PEER NGA-E project [Dreger - 2015]. [Maechling - 2015] Maechling, P. J., F. Silva, S. Callaghan, and T. H. Jordan (2015). SCEC Broadband Platform: System Architecture and Software Implementation, Seismol. Res. Lett., 86, no. 1, doi: 10.1785/0220140125 [Dreger - 2015] Dreger, D. S., Beroza, G.C., Day, S. M., Goulet, C. A., Jordan, T. H., Spudich, P. A., and Stewart, J. P. (2015). Validation of the SCEC Broadband Platform V14.3 Simulation Methods Using Pseudospectral Acceleration Data, Seismol. Res. Lett., 86, no. 1, doi:10.1785/0220140118.

SCEC Supercomputer Allocations SCEC received 167M SUs and nearly 800TB of temporary storage on DOE INCITE computers in 2015, and received 12.2M node hours (~390M CPU hours) and nearly 2PB temporary data storage on NSF Blue Waters computer in 2015-2016. SCEC also received allocations on USC HPC and XSEDE computers in 2015.

SCEC At National HPC Meetings Thomas H. Jordan presented plenary research talks at both the 2014 Blue Waters Meeting and the 2014 Oak Ridge National Lab User Meeting and Philip J. Maechling presented at the 2015 Blue Waters Meeting.

CyberShake Study 14.2 (2014) at 0.5Hz In 2014, SCEC used NSF Blue Waters to calculate 4 alternative southern California Physics-based PSHA CyberShake hazard models based on CVM-S4, CVM-H, BBP 1D model, and CVM-S4.26. These simulations integrated results from UCERF-2, BBP project, USR, full 3D tomography, and SCEC’s HPC GPU code development efforts.

CyberShake Study 15.4 (2015) at 1.0Hz In 2015, SCEC used NSF Blue Waters and DOE Oak Ridge Leadership Computing (OLCF) Titan computers to calculate a 1Hz Los Angeles Region CyberShake hazard model. These calculations are being used to extend the CyberShake urban seismic hazard model for the Los Angeles region up to seismic frequencies as high as 0.5 Hz.

Risk-Targeted Maximum Considered Earthquake Response Spectra (MCER) SCEC has held meetings to discuss CyberShake calculations in collaboration with ASCE and USGS engineering groups. CyberShake 14.2 Combined MCER Results 3s RotD100 (286 Sites)

High-Frequency La Habra Simulations at 4.0Hz SCEC High-F high frequency ground motion simulation groups including Kim Olsen, Jacobo Bielak, and Ricardo Taborda have initiated a ground motion modeling validation activity that will simulate historic earthquakes at 4Hz and higher frequencies. Two groups have produced ground motion simulation results at 4Hz using alternative methods. Initial results are for simple velocity models, and will build complexity towards validation against observations. May 2015 4Hz Simulation Comparison AWP-ODC (FD) versus Hercules (FE)

CSEP Testing Center SCEC continues to extended, enhanced, and operate the CSEP testing center. Maria Liukis has worked with CSEP scientists in order to create a series of new CSEP releases including January, April, and October 2014, and January, and April 2015.

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