The temperature 3,000 kilometers below the surface of the Earth is much more varied than previously thought

December 17, 2015
The team used the TerraWulf high-end computing cluster to generate their map. Credit: Stuart Hay, ANU

The temperature 3,000 kilometres below the surface of the Earth is much more varied than previously thought, scientists have found.

The discovery of the regional variations in the where it meets the , which are up to three times greater than expected, will help scientists explain the structure of the Earth and how it formed.

"Where the mantle meets the core is a more dramatic boundary than the surface of the Earth," said the lead researcher, Associate Professor Hrvoje Tkalčić, from The Australian National University (ANU).

"The contrast between the solid mantle and the liquid core is greater than the contrast between the ground and the air. The core is like a planet within a planet." said Associate Professor Tkalčić, a geophysicist in the ANU Research School of Earth Sciences.

"The centre of the is harder to study than the centre of the sun."

Temperatures in the lower mantle the reach around 3,000-3,500 degrees Celsius and the barometer reads about 125 gigapascals, about one and a quarter million times atmospheric pressure.

Variations in these temperatures and other material properties such as density and chemical composition affect the speed at which waves travel through the Earth.

The team examined more than 4,000 seismometers measurements of earthquakes from around the world.

In a process similar to a CT scan, the team then ran a complex mathematical process to unravel the data and build the most detailed global map of the lower mantle, showing features ranging from as large as the entire hemisphere down to 400 kilometres across.

The map showed the seismic speeds varied more than expected over these distances and were probably driven by heat transfer across the core-mantle boundary and radioactivity.

"These images will help us understand how convection connects the Earth's surface with the bottom of the ," said Associate Professor Tkalčić.

"These thermal variations also have profound implications for the geodynamo in the core, which creates the Earth's magnetic field."

The study is published in Scientific Reports.

Explore further: Earth's center is out of sync

Related Stories

Earth's center is out of sync

May 13, 2013

(Phys.org) —We all know that the Earth rotates beneath our feet, but new research from ANU has revealed that the center of the Earth is out of sync with the rest of the planet, frequently speeding up and slowing down.

Developing a picture of the Earth's mantle

December 14, 2015

Deep inside the earth, seismic observations reveal that three distinct structures make up the boundary between the earth's metallic core and overlying silicate mantle at a depth of about 2,900 kilometers—an area whose composition ...

Earth's lower mantle chemistry breakthrough

May 22, 2014

Breaking research news from a team of scientists led by Carnegie's Ho-kwang "Dave" Mao reveals that the composition of the Earth's lower mantle may be significantly different than previously thought. These results are to ...

New insight into the temperature of deep Earth

May 22, 2014

Scientists from the Magma and Volcanoes Laboratory (CNRS) and the European Synchrotron, the ESRF, have recreated the extreme conditions 600 to 2900 km below the Earth's surface to investigate the melting of basalt in the ...

Gradients in the Earth's outermost core

December 8, 2010

Evidence that the outermost portion of the Earth’s core is stratified is provided by earthquake data reported by scientists at the University of Bristol this week in Nature.

Recommended for you

Scientists solve mystery of unexplained 'bright nights'

June 21, 2017

Dating back to the first century, scientists, philosophers and reporters have noted the occasional occurrence of "bright nights," when an unexplained glow in the night sky lets observers see distant mountains, read a newspaper ...

New research leverages big data to predict severe weather

June 21, 2017

Every year, severe weather endangers millions of people and causes billions of dollars in damage worldwide. But new research from Penn State's College of Information Sciences and Technology (IST) and AccuWeather has found ...

Measuring biological dust in the wind

June 21, 2017

In the popular children's story "Horton Hears a Who!" author Dr. Seuss tells of a gentle and protective elephant who stumbles upon a speck of dust that harbors a community of microscopic creatures called the Whos living the ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.