New layer of Earth is discovered 100 miles below the surface: Region of molten rock covers at least 44% of our planet
Scientists have discovered a hidden layer of Earth, which sits 100 miles below the surface and covers at least 44 percent of the planet.
This previously unknown region of molten rock is part of the asthenosphere, located under tectonic plates in the upper mantle, which forms a soft boundary that allows the solid rock slabs to move.
While the discovery is significant, it shatters long-held theories that molten rocks influence the asthenosphere’s viscosity.
Junlin Hua, with the University of Texas, Austin, said in a statement: ‘When we think about something melting, we intuitively think that the melt must play a big role in the material’s viscosity.
‘But what we found is that even where the melt fraction is quite high, its effect on mantle flow is very minor.’
Junlin Hua, with the University of Texas, Austin, said in a statement: ‘When we think about something melting, we intuitively think that the melt must play a big role in the material’s viscosity.
‘But what we found is that even where the melt fraction is quite high, its effect on mantle flow is very minor.’
The idea to look for a new layer in Earth’s interior came to Hua while studying seismic images of the mantle beneath Turkey during his doctoral research.
Intrigued by signs of partly molten rock under the crust, Hua compiled similar images from other seismic stations until he had a global map of the asthenosphere.
What he and others had taken to be an anomaly was commonplace around the world, appearing on seismic readings wherever the asthenosphere was hottest.
The next surprise came when he compared his melt map with seismic measurements of tectonic movement and found no correlation, despite the molten layer encompassing almost half the Earth.
Coauthor Karen Fischer, a seismologist and professor at Brown University, said: ‘This work is important because understanding the properties of the asthenosphere and the origins of why it’s weak is fundamental to understanding plate tectonics.’
The discovery of a new layer comes less than one month after scientists announced that Earth’s inner core rotation is slowing down.
A team from Peking University in China revealed that days on Earth could be increasing in length, thanks to changes in the rotation speed of our planet’s inner core.
Source: daily mail
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New layer of Earth is discovered 100 miles below the surface: Region of molten rock covers at least 44% of our planet