Earth’s Interior ‘Holds as Much Water as All the Oceans Combined’

There are six quintillion gallons of water buried beneath the Earth’s crust

The stone rode a violent volcanic eruption to the surface from 325 miles within the Earth’s mantle, and it was discovered in 2016. “The eruption … is comparable to dropping a Mentos mint into a bottle of soda,” Graham Pearson, a geochemist at the University of Alberta, said. “It’s a very active, gas-charged reaction that shoots its way to the planet’s surface.”

The sponge-like ringwoodite is normally only seen in meteorites or laboratories, but this time it was different. This time, extreme pressure had formed it into a new rock type containing 1.5% water; thus confirming that the Earth’s insides are very wet indeed. According to Pearson, “It translates into a very large mass of water, similar in size to all the world’s oceans combined.” In addition, it may be much more than that, according to new research published in this issue of Science. The findings, according to the researchers, reveal what makes our planet blue and how the Earth came into existence. According to present thinking, the oceans were not created through icy comets as previously supposed but rather resulted from tectonic and geological activity that led water to the surface.

“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,” Steve Jacobson, a co-author of the study and a professor at Northwestern University, said in a statement. “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.”

Scientists have long suspected there was a lot of water beneath our feet, but this may be the first direct evidence of it. Researchers found a vast reservoir of water locked inside the mantle’s “transitional zone.” The significance: If just 1 percent of the “transitional zone” is made up of water, it would triple the amount on Earth’s surface.

According to the research, rock melting and shifting in the transition zone trap water. “It’s strong evidence that the Earth’s water came from within,” Jacobsen told New Scientist.

Of course, it isn’t the sort you can put in your Brita filter or save a lost hiker. It’s imprisoned within the rock’s molecular structure.

READ MORE: What if you were told that Earth’s most abundant source of water is found deep in its core – and is stored in its rocks and magma to be released under the heat and pressure of geologic events and circumstances?

The researchers arrived at that conclusion by studying the seismic waves resulting from North American earthquakes. This allowed them a glimpse into the regional deep crust. Afterwards, to verify their hypothesis, they put ringwoodite under conditions similar to those found 400 miles below Earth’s surface, which exhibited how the water becomes trapped.

“When a rock with a lot of H20 moves from the transition zone to the lower mantle it needs to get rid of the H20 somehow, so it melts a little bit,” Schmandt said. “This is called dehydration melting.”

Then, “once the water is released,” researcher Jacobsen said, “much of it may become trapped there in the transition zone” about 400 miles deep in the Earth.

Jacobsen told New Scientist that this is a good thing: “We should be grateful for this deep reservoir. If it wasn’t there, it would be on the surface of the Earth, and mountain tops would be the only land poking out.”