Computer model takes in earthquake data and runs a simulation in real time

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Annie O'Neill, Post-Gazette
The earth moves when Dr. Jacobo Bielak, left, and Dr. David O'Hallaron, of Carnegie Mellon University, get together. They are involved in creating supercomputer simulations of earthquakes to study their impact on the ground, people and buildings.
Click photo for larger image.

The best way to describe research at Carnegie Mellon University that uses Pittsburgh Supercomputing Center equipment is "earth-shaking."

For starters, the research focuses on earthquakes. But it also uses novel methods of simulating earthquake physics with the goal of saving lives, buildings and infrastructure in Southern California.

Jacobo Bielak, David O'Hallaron and their "Quake Group" of six other researchers in CMU's Computational Seismology Laboratory and computer science department have used PSC's "BigBen" supercomputer to simulate a Los Angeles-area earthquake and show how ground motions propagated destruction in a 70,000-square-mile region.

"This work already is being used in practice by the California Department of Transportation," said Dr. Bielak, CMU professor of civil and environmental engineering.

Since 1993, CMU's team has participated in research at Southern California Earthquake Center based at the University of Southern California.

"We are the only ones not in California," Dr. Bielak said. "We have the luxury of working with them without the fear of an earthquake."

Last week, the team ran a supercomputer simulation that used its Hercules computation code and analysis method to perform complex supercomputer simulations with 2,048 processors running simultaneously to reach higher levels of resolution. The simulation shows how ground motion from an earthquake selects a propagation path to spread throughout a region, but affects some areas more than others.

"Because of the work we do, we have a much better understanding of the entire earthquake phenomenon from the source through the propagation path of waves and local side effects," Dr. Bielak said.

The successful simulation marks the latest research tremor in a string of successes.

In November, the team -- which includes researchers from the University of Texas, University of California, Davis, and the supercomputing center -- won the SC06 Analytics Challenge Award in Tampa, Fla., for its earthquake simulation that explains why earthquakes so dramatically affect populated basins such as Los Angeles.

The international conference focuses on high-performance computing, networking, data storage and analysis. Tiankai Tu led the CMU team's effort.

Software to run the simulation allows interaction between the supercomputer and a remote laptop computer that controls the program. With a laptop, a researcher can change view angles, zoom in or out and do other operations while real-time visualization from a program known as "QuakeShow" is running.

For the competition, the team simulated the 1994 Northridge Earthquake, whose epicenter was 6 miles north of Los Angeles. The quake killed 51 people and did $44 billion in damage, even though it registered only 6.7 on the Richter scale.

Earthquakes in that region can measure 7.5, or higher. A 7.7 earthquake would be 14 times the power of 1994 Northridge.

But the simulation accurately showed why so much damage occurred in 1994 Northridge.

CMU and PSC's research validates theories that strong concentrations of seismic energy occur in California's San Fernando Valley and the Los Angeles Basin because of their geological characteristics. Both are sedimentary basins that trap seismic energy during strong earthquakes and shake like Jell-O, heightening the impact.

The Quake Team's computer simulations show in great detail how earthquake waves travel from the epicenter on the San Andreas Fault and are directed by mountain ranges straight to Los Angeles.

"We make a model of geology for an entire region, then we shake it and find out what happens over the entire region," Dr. Bielak said. "We use Southern California as our laboratory."

In the future, CMU researchers hope to ramp up earthquake wave frequencies to levels important to engineers who design buildings and infrastructure in earthquake zones. Higher-wave frequencies cause the greatest structure damage.

Also in the works is simulation of an earthquake 7.7 on the Richter scale. The team also hopes to simulate past earthquakes to see if their models produce the same effects.

In time, they hope to simulate earthquakes yet to occur, but certain to happen based on earthquake patterns. Once they model them, they can gauge the impact and help the area prepare for the actual quake.

Drs. Bielak and O'Hallaron, an associate professor in computer science and electrical and computer engineering, said their models can help engineers establish building codes so new structures can better withstand earthquakes.

"We try to explain why structures collapse or suffer damage and why no damage occurs, and why the ground motion was different," Dr. Bielak said. "We learn from both."

"It's amazing that we get the same wiggles," Dr. O'Hallaron said. "The fact we're as close as we are is a real miracle."


David Templeton can be reached at dtempleton@post-gazette.com or 412-263-1578.


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