Feature - Making the Earth Move 

The warm colors leading from the fault region into the Los Angeles area illustrate how a chain of sedimentary basins can guide earthquake waves away from the fault where they originate into heavily populated regions in Southern California. Image courtesy of Amit Chourasia, San Diego Supercomputing Center.

An ambitious group of more than 40 institutions, together called the Southern California Earthquake Center, is building earthquake modeling capabilities to transform seismology into a predictive science similar to weather forecasting.

To bring that vision to life, SCEC has built a set of grid-based scientific workflow tools. A series of simulations based on these tools—TeraShake 1, TeraShake 2, and the most recent CyberShake—began in 2004. They've run on TeraGrid resources across the country and are already yielding significant results.

TeraShake 2, for example, simulated a series of earthquakes along the San Andreas Fault. Run in concert at NCSA and SDSC, it revealed a striking contrast in ground motion between ruptures that started at the northwestern end of the fault and those that started at the southeastern end.

Hazard curves calculated by CyberShake, meanwhile, tend to be significantly different than those issued by the U.S. Geological Survey, which are considered standard. If these curves, which building designers use to estimate the peak ground motions that will occur over the lifetime of a building, are correct, this type of calculation could significantly change the character of the national probabilistic earthquake hazard maps.

Simulations using TeraGrid resources at PSC are replicating the TeraShake 2 run at a higher level of resolution.

“The success of our national initiatives in supercomputing depends on the integration of hardware, software, and wetware, that is technical expertise, into an effective cyberinfrastructure. We have been leveraging our partnership with TeraGrid to promote this vertical integration,” says Tom Jordan, SCEC’s director and an earth sciences professor at the University of Southern California.

This article appeared as a 2006 Science Highlight on the TeraGrid Web site.

- Bill Bell, National Center for Supercomputing Applications