iSGTW Feature - Ground-shaking research relies on Herculean computing

Feature - Ground-shaking research relies on Herculean computing

Examining how and why different earthquake simulation programs produce different results is important for their validation. This shows the displacement from soil vibration in a quake simulated using Hercules (top) as compared to the same region simulated using TeraShake. (bottom).
Image courtesy of Pittsburgh Supercomputing Center

The basic goal of earthquake research is to know how the Earth will shake.

Even from one city block to the next, the level of shaking can change dramatically due to subsurface soil and the nature of the seismic waves," says Jacobo Bielak, professor of civil and environmental engineering at Carnegie Mellon University.

Bielak and his colleague David O'Hallaron lead the Quake Project, a large collaborative research team that uses sophisticated computational methods to create realistic 3D models of earthquakes.

In collaboration with the Southern California Earthquake Center (SCEC), their work aims to provide information that will result in seismic provisions in building codes that will ensure the safest possible structures at reasonable cost.

SCEC and the Quake Project rely heavily on TeraGrid resources.

Herculean effort

In November 2006, the Quake team won the Analytics Challenge Award at SC06 in Tampa for "Hercules"-software that coordinates all the stages of very large-scale earthquake simulation, from problem definition to final visualization.

With this unified framework, all tasks-building a software mesh that subdivides the subsurface region, partitioning the job among hundreds or thousands of processors, the simulation itself, and visualizing results-can be performed in place on the processors of a supercomputer.

Relying on innovative software developed at Pittsburgh Supercomputing Center, Hercules can visualize results in real time as a simulation is running.

2,048 processors to the rescue

In December 2006, the Quake team used Hercules with 2,048 processors of PSC's Cray XT3 for an unprecedented computation, simulating a magnitude 7.7 quake along the San Andreas fault using realistic soil properties and a high-frequency vibration of one cycle per second.

Higher frequencies greatly increase the size of the computation but are important because they help represent the structures that present the greatest danger.

This Hercules simulation showed specifics on how ground motion selects a propagation path and affects some areas more than others.

PSC staff are developing user-friendly visualization tools to compare results from Hercules with TeraShake, earthquake simulation software developed at SCEC.

Computer-aided planning can help cities like Istanbul prepare for future quakes.
Image courtesy of Teragrid

A new city for Istanbul

Istanbul, populated by 12 million people in brittle concrete and masonry housing, has been devastated by earthquakes many times in its history, and the next catastrophe is only a matter of time.

As part of advance planning for this dreaded event, the Istanbul city government commissioned a team at Purdue University led by Nicoletta Adamo-Villani and Mete Sozen to design and visualize a satellite city.

Their plan includes a business district, research and government centers, retail and cultural facilities, with all construction earthquake resistant.

After the team created the city plan in AutoCAD and modeled the city in Maya, a major challenge was to render the final sequence by their deadline.

To accomplish this, they relied on TeraGrid software called TeraDRE (Distributed Rendering Environment on the TeraGrid) and a TeraGrid cluster of 4,000 PCs spread across the Purdue campus.

This story features in Teragrid's 2007 Science Highlights booklet, to be released at Supercomputing 2008 next month.