May 17, 2004
Researchers study early warning system for quakes
CARBONDALE, Ill. -- Research at Southern Illinois University Carbondale could one day provide an advance earthquake warning system.
The study focuses on whether underground co-seismic electrical currents exist during earthquakes, and whether those currents could one day serve to warn highly populated and industrial areas of an earthquake.
Eric C. Ferre, an assistant professor and structural geologist in SIUC's geology department, along with Navani MathanaSekaran, a graduate student in electrical engineering, and Matthew Zeckmeister, a graduate student in geology, are participating in the research. The project, which also involves collaboration with the University of New Mexico and Shizuoka University in Japan, received $190,000 last year from the National Science Foundation.
The pseudotachylites practically act as a "black box," or flight recorder, said Ferre.Because underground co-seismic electrical currents happen quickly, and predicting the location of an earthquake is impossible, geologists are studying fault planes, or cracks within the earth's crust, to determine if an earthquake generated an electrical current in the past. Friction in the earth's crust during an earthquake produces rising temperatures, and the frictional melting results in the formation of a pseudotachylite vein along the fault plane. A pseudotachylite is a rock found along a fault produced by melting due to frictional slip during an earthquake.
"Anything that happens during the earthquake is recorded in those rocks," he said. "So it is very easy for us to go back to these rocks and find out what information is inside."
The "black box" records temperature readings and information pertaining to electrical currents and magnetism. Electrical currents and magnetism are intimately linked, and the magnetic record within the pseudotachylite can reveal if there was an electrical current also passing through during an earthquake, said Ferre. There are a number of factors, including rock type and an earthquake's magnitude, that determines if an electrical current is present, he said.
"It happens during an earthquake, but we are not yet sure that it is directly related to the earthquake," he said.
Because of the existing large-scale power grids, there remains ambiguity on whether electrical currents do exist, said Ferre. An earthquake is likely to damage a large electrical power grid, which results in an artificial man-made electrical current that leaks into the ground, he said.
Electric waves travel faster than sound waves, so detecting electrical currents during large-magnitude earthquakes will provide more advance warning time than relying on seismic waves, Ferre said, demonstrating the seismic motion by quickly snapping an extended Slinky at one end to illustrate what happens in earthquakes.
If, for example, an earthquake occurs in New Madrid, Mo., which is about 93 miles southwest of Carbondale, it will take about one to one-and-one-half minutes, depending on the rock types, for earthquake waves to reach Carbondale.
Because electricity travels at 300,000 km per second, the ability to detect electrical currents will greatly enhance warning systems, Ferre said.
"It is providing almost real-time warning," he said. "At the moment, what we have is a grid, or network of interconnected seismometers. If an earthquake takes place in New Madrid, it's going to take almost two minutes before our seismometer records anything here."
In most major industrial areas along the West Coast, there are devices that record seismic information and transmit information to power plants and other large industrial facilities to automatically shut them down in instances of a magnitude 5.0 or higher earthquake, said Ferre.
In November, Ferre presented initial research results at the annual meeting of the Geological Society of America in Seattle. The first paper, which lays out the theory, research fundamentals and some initial data, will appear in a special issue of Techtonophysics, hopefully by the end of summer. A second paper, which presents data on how pseudotachylites behave like lightning rods, is nearing completion, he said.
At the meeting last fall in Seattle, Ferre's audience included experts in the seismological community "because we want to bring these people in and we want them to listen to what we are doing," he said.
Researchers are working on pseudotachylites from around the world while Ferre and his students work on samples from California, the Italian Alps and Japan.
Ferre also expects by the end of the year to be able to produce the same rock types -- under controlled laboratory conditions -- in Japan. Researchers will artificially melt rocks using frictional heat and measure the samples' magnetic properties to determine if there are electrical currents during the deformation process.
Due to the frequency of earthquakes in Japan, researchers there have built some of the best laboratories in the world when it comes to simulating earthquakes, and also reproducing building behaviors during earthquakes, Ferre said.
Leading in research and scholarly activities that provide for new scientific discoveries is among the goals of Southern@150, the blueprint for the development of the University by the time it celebrates its 150th anniversary in 2019.
For more information on the research, contact assistant professor Eric C. Ferre at 618/453-7368.