Scientists have discovered evidence of a vast water reservoir trapped hundreds of miles beneath the surface, capable of filling Earth’s oceans three times over.
Located 400 miles (660 km) beneath Earth’s crust, this body of water is locked up in a blue mineral called ringwoodite that lies in the transition zone of hot rock between Earth’s surface and core. Interestingly, this water is not in a form familiar to us – it’s neither liquid, ice nor vapor. Geophysicist Steve Jacobsen from Northwestern University suggests it means that water on Earth may get pushed to the surface from below, contradicting previous beliefs that water was delivered via icy comets.
“Geological processes on the Earth’s surface, such as earthquakes or erupting volcanoes, are an expression of what is going on inside the Earth, out of our sight,” Jacobsen, co-author of the paper published in the journal Science, said in a press release.
“I think we are finally seeing evidence for a whole-Earth water cycle, which may help explain the vast amount of liquid water on the surface of our habitable planet. Scientists have been looking for this missing deep water for decades.”
Ringwoodite here is key. Its crystal-like structure makes it act like a sponge and draw in hydrogen and trap water.
Jacobsen and his colleagues based their findings on a study of the transition zone, an underground region extending across most of the interior of the United States.
Along with Jacobsen’s lab experiments on rocks simulating the high pressures found deep underground, the study compiled data from the USArray, a network of seismometers across the United States used to measure earthquake vibrations.
It produced evidence that melting occurring 400 miles beneath the surface, plus the movement of rock in the transition zone, leads to a process where water can become fused and trapped within the rock.
Scientists were astounded because most melting in the mantle was previously thought to occur at a much shallower distance – about 50 miles (80km) below the Earth’s surface.
And according to The Guardian, Jacobsen said that this trapped, hidden water may explain why Earth’s oceans have stayed the same size for billions of years.
“If [the stored water] wasn’t there, it would be on the surface of the Earth, and mountaintops would be the only land poking out,” he said.
The findings were published June 13 in the journal Science.