Earthquakes Help Take Deep Earth's Temperature

Christine Dell'Amore
for National Geographic News
March 29, 2007

New high-resolution seismic images have produced the best estimate to date of the temperature of Earth's extremely deep interior, researchers report.

Using a method initially developed for oil and gas exploration, the scientists studied the core-mantle boundary, a region that lies about 1,860 miles (3,000 kilometers) below the planet's surface.

This technique allowed the team to piece together images based on seismic waves bounced off materials around the boundary.

The resulting 3-D map of the region revealed minerals and pressure levels that indicated the surrounding temperature.

Reporting in tomorrow's issue of the journal Science, the team calculated that the temperature of the region is 3,950 Kelvin, plus or minus 200.

This translates to a fiery 6,650 degrees Fahrenheit (3,677 degrees Celsius)—which is actually lower than previous predictions.

Robert van der Hilst is an earth science professor at the Massachusetts Institute of Technology and lead author of the new study.

"These findings are exciting," he said, "because they demonstrate these techniques adapted from the oil industry actually work" for geologic research.

"My group and I take this as an enormously encouraging development."

Seismic Map

Van der Hilst's team studied data from earthquake-prone areas of Central America.

The regions are among the few in the world where a large number of quakes occur close enough to seismographic stations for scientists to record earthquakes' seismic waves bounced back from the core.

Continued on Next Page >>




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