An SIUC geophysicist who studies the earth's magnetic and gravitational fields has won a three-year, $182,000 grant from the National Aeronautics and Space Administration (NASA) for research that may be helpful to understanding both earthquakes and extinctions.

Dhananjay "Tiku" Ravat, an associate professor of geology, will use satellite data to study magnetic field variations in the portion of the earth covered by the United States. These variations relate to temperatures inside the earth, and internal temperatures are a key indicator of the strength or weakness of the country's underlying tectonic plates. Hotter temperatures at shallower depths mean weaker plates.

"This may tell us which areas are most susceptible in the long term to natural hazards such as earthquakes or volcanoes," Ravat says.

Long term means hundreds of millions of years, he stresses.

"We're not talking about tomorrow. But the parameters our students and I will derive regarding temperature and strength of tectonic plates will be directly usable by other researchers studying these hazards during the next decade."

U.S. scientists who use Ravat's results will be able to use more precise parameters in their studies of these natural hazards.

"They have been using average values indirectly derived for their analyses," Ravat says.

"After this, a seismologist who studies earthquakes will be able to take into account more precisely the variability in the strength of the Earth's crust around New Madrid, for example, as opposed to San Francisco." (The earthquakes centered in the New Madrid, Mo., region in 1811-12 were the strongest in U.S. history.)

Foreign scientists will also benefit, as they can apply the methods Ravat develops to satellite data gathered over their countries.

"This will benefit their understanding of Earth's outer layers and natural hazards in their own regions," Ravat says.

Variations in both the magnetic and gravitational fields of the earth also can help identify areas where huge meteors have smashed into the earth, Ravat says. Time has often altered such sites beyond recognition, so geologists studying the surface cannot find them easily.

"If we could identify these impact sites with satellite-altitude magnetic data, studies of mass extinctions could then be much better correlated with particular impacts," Ravat explains.

"We could figure out their timelines, which would give us a much better idea of how life evolved on earth."

Ravat's research has been funded by NASA since 1994.

--by K. C. Jaehnig, Media & Communication Resources

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