Annual Meeting - SCEC.org

Poster Abstracts | Group 1 – SHRA
Purdue University, SCEC researchers and computer scientists were able to create probabilistic
seismic hazard maps at very high resolution using Open Seismic Hazard Analysis (OpenSHA).
OpenSHA is an open-source seismic hazard framework developed as a joint project between the
Southern California Earthquake Center and the United States Geological Survey. While OpenSHA
currently implements Earthquake Rupture Forecasts and attenuation relationships only for
California, we were able to demonstrate that OpenSHA can scale-up computationally to the scale
required to produce global hazard maps. We demonstrated this by discretizing California at a very
fine level, resulting in over 1.6 million hazard curves, and calculating a very high-resolution PSHA
hazard map for California. The number of curves in our very high resolution California PSHA
maps is comparable to the number of curves required to produce a global hazard maps at 10 km
spacing. Demonstrating this type of scalability is an essential step towards meeting the needs of the
Global Earthquake Model (GEM) program's goal of generating uniform, worldwide seismic hazard
maps.
It took almost 18,000 CPU hours to generate all 1.6 million curves, which we completed in 51 wall
clock hours on 400 CPU cores (including overhead). The curves were calculated using the Working
Group on California Earthquake Probabilities' 2007 Uniform California Earthquake Rupture
Forecast (UCERF), an extremely computationally complex forecast that requires much more
computation time than forecasts for other parts of the world. This suggests that a Global run could
be computed in less CPU time using simpler models. One major achievement was making the
hazard map creation workflow as portable and automatic as possible. In fact, it is just as easy to
run the workflow at the University of Southern California's HPC cluster as it is on many of the
clusters that are part of the National Science Foundation's TeraGrid grid infrastructure. The 1.6
million curve workflow was run on the National Center for Supercomputing Applications
(NCSA)'s Abe cluster.
1-036
SEISMIC LOSS ESTIMATION BASED ON END-TO-END SIMULATION Muto M,
Krishnan S, Beck JL, and Mitrani-Reiser J
Recently, there has been increasing interest in simulating all aspects of the seismic risk problem,
from the source mechanism to the propagation of seismic waves to nonlinear time-history analysis
of structural response and finally to building damage and repair costs. This study presents a
framework for performing truly “end-to-end” simulation. A recent region-wide study of tall steelframe
building response to a M7.9 scenario earthquake on the southern portion of the San Andreas
Fault is extended to consider economic losses. In that study a source mechanism model and a
velocity model, in conjunction with a finite-element model of Southern California, were used to
calculate ground motions at 636 sites throughout the San Fernando and Los Angeles basins. At
each site, time history analyses of a nonlinear deteriorating structural model of an 18-story steel
moment-resisting frame building were performed, using both a pre-Northridge earthquake design
(with welds at the moment-resisting connections that are susceptible to fracture) and a modern
code (UBC 1997) design. This work uses the simulation results to estimate losses by applying the
MDLA (Matlab Damage and Loss Analysis) toolbox, developed to implement the PEER lossestimation
methodology. The toolbox includes damage prediction and repair cost estimation for
structural and non-structural components and allows for the computation of the mean and
variance of building repair costs conditional on engineering demand parameters (i.e. inter-story
drift ratios and peak floor accelerations). Here, it is modified to treat steel-frame high-rises,
including aspects such as mechanical, electrical and plumbing systems, traction elevators, and the
possibility of irreparable structural damage. Contour plots of conditional mean losses are
generated for the San Fernando and the Los Angeles basins for the pre-Northridge and modern
86 | Southern California Earthquake Center