Annual Meeting - SCEC.org

Group 1 – CME/PetaSHA | Poster Abstracts
dimensional slices via a clickable interface or by specifying precise coordinates. Extractions are
plotted to the screen and optionally downloaded to local disk. Time histories may be low-pass
filtered, and multiple simulations may be overlayed for comparison. Metadata is sored with each
simulation in the form of a Pylab module. A well defined URL scheme for specifying extractions
allows the web interface to be bypassed, thus allowing for batch scripting of both plotting and
download tasks. This version of WebSims replaces a previous PHP implementation. It is written in
Python using the NumPy, SciPy, and Matplotlib modules, which provide a MATLAB-like
processing and visualization environment. The web pages are served by a web.py, a simple web
application framework similar to Google App Engine. WebSims is open source and freely
available, though not supported.
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RUNNING MILLIONS OF SERIAL JOBS ON A CLUSTER USING WORKFLOWS:
CYBERSHAKE 2008 Callaghan S, Maechling PJ, Deelman E, Vahi K, Mehta G, Juve G, Milner
KR, Graves RW, Field E, Okaya DA, and Jordan TH
SCEC researchers use large-scale computational grid-based scientific workflows to perform seismic
hazard calculations for the CyberShake project, part of SCEC's PetaSHA project. The scientific goal
of CyberShake is to calculate physics-based probabilistic seismic hazard curves for locations in
Southern California and combine the curves into a hazard map for the region. For each site of
interest, the CyberShake processing includes two large-scale MPI calculations to create strain
Green's tensors and a large number of embarrassingly parallel post-processing jobs to calculate
intensity measures from possible events. These intensity measures are then processed into a hazard
curve.
Our use of scientific workflows, which link the output of one job with the input of the next, enables
a greater degree of automation and supports access to the grid tools needed to run and manage this
kind of high-throughput calculation. CyberShake has been updated to include the UCERF 2.0
earthquake rupture forecast (ERF), as well as increased rupture variation in hypocenter location
and slip distribution. As a result, the number of calculations per site increased by a factor of four,
leading to workflows of nearly 1 million jobs. We have recently completed CyberShake seismic
hazard curves for 9 sites utilizing large workflows, using the Pegasus Workflow Management
System to execute the computations on local and national supercomputing resources. We discuss
the advantages of using a grid-based, scientific workflow approach to this type of high-throughput
computation. We describe the challenges we encountered and solutions we developed to obtain
meaningful scientific results.
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SCEC RESEARCH USING HIGH PERFORMANCE COMPUTING BY THE SCEC/CME
COLLABORATION Maechling PJ, Jordan TH, Archuleta RJ, Beroza GC, Bielak J, Chen P,
Cui Y, Day SM, Deelman E, Graves RW, Minster JB, Olsen KB, and the SCEC/CME
Collaboration
The SCEC Community Modeling Environment (SCEC/CME) collaboration performs basic
scientific research using high performance computing with the goal of developing a predictive
understanding of earthquake processes and seismic hazards. SCEC/CME research is currently
funded through two NSF awards, the NSF-EAR PetaSHA-2 project, and the NSF-OCI PetaShake
projects. These two projects have complementary goals with PetaSHA-2 focusing on basic seismic
hazard research and PetaShake focusing on increasing the scale and resolution of SCEC
computational codes to use petascale supercomputers. SCEC/CME research areas including
dynamic rupture modeling, wave propagation modeling, probabilistic seismic hazard analysis, and
2008 SCEC Annual Meeting | 79