A new layer deep inside our planet that acts as the Earth's natural lubricant may have been discovered.
Researchers at the University of California, San Diego found that there may be a liquefied layer of molten rock that separates the mantle from the tectonic plates.
"This was completely unexpected," said geophysicist Kerry Key.
"We went out looking to get an idea of how fluids are interacting with plate subduction, but we discovered a melt layer we weren't expecting to find at all -- it was pretty surprising."
The new layer was discovered during a research mission off the coast of Nicaragua in 2010.
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Using electromagnetic signals sent into the Earth from instruments on the seafloor, researchers discovered magma below the tectonic plates.
What allows tectonic plates to move has been up for debate among scientists.
Some have argued that water has acted as a lubricant for the plates but new findings point to magma.
“Our data tell us that water can’t accommodate the features we are seeing,” graduate student Samer Naif, who worked on the study, said.
“The information from the new images confirms the idea that there needs to be some amount of melt in the upper mantle and that’s really what’s creating this ductile behavior for plates to slide.”
The findings were published in the journal Nature.