Earth © NASAWashington, Mar 30 (ANI): US scientists have used a novel method initially developed for oil and gas exploration to create high resolution seismic images that have produced the best estimate to date of the temperature of Earth’s extremely deep interior.
Researchers have studied the core-mantle boundary, a region that lies about 1,860 miles (3,000 kilometres) below the planet's surface. The technique allowed them to piece together images based on seismic waves bouncing off materials around the boundary.
The resulting 3-D map of the region revealed minerals and pressure levels that indicated the surrounding temperature of the region of 3,950 Kelvin, plus or minus 200, which roughly translates to a fiery 6,650 degrees Fahrenheit (3,677 degrees Celsius), scientists said of their findings in the journal Science.
This is however, actually lower than previous predictions, they said.
"These findings are exciting 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,” said Robert van der Hilst, an earth science professor at the Massachusetts Institute of Technology and lead author of the new study.
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.
The team compiled data from thousands of earthquakes recorded at more than a thousand stations to create a detailed 3-D map of the core-mantle boundary. Using this map, the team then estimated the temperature based on two key factors: pressure and mineral content.
While scientists already knew the temperature at which a mineral in the mantle called pervoskite transformed into a high-pressure material called post-pervoskite, they didn’t know where this transition took place.
Findings revealed the metamorphosis took place in the lowermost mantle, just above the core, which in turn provided a correlating temperature for the core-mantle boundary.
Donald Helmberger, a professor of geological and planetary sciences at the California Institute of Technology said such findings could shed light on how heat flows from Earth's core into the mantle.
“This heat flow drives the planet's magnetic field and is still poorly understood. Every technique we can bring to bear to study these things is a step forward," National Geographic quoted Helmberger as saying.
Edward Garnero, a professor of geological sciences at Arizona State University who also uses seismology to study the deep interior, said this kind of research could demystify how the planet evolved.
Knowing Earth's temperature at such depths can tell scientists how much the core has cooled over time and how fast it is cooling now. We live on this amazing planet, and we still don't know for certain the processes that go on inside it. This paper represents another little piece that brings it into a sharper focus,” Garnero said. (ANI)