Vast Oceans of Water Trapped Beneath Earth’s Mantle?

Large amounts of ocean water could be transported through deep-sea fault zones in volumes much greater than previously believed, according to new research from the University of Liverpool, which focused on the subduction zone that led to the 2011 Tohoku earthquake in Japan.

The research supports the theory that there could be vast amounts of water buried deep beneath the Earth’s mantle.

Understanding how much ocean water is delivered to the mantle is important because it helps explain how the mantle bows and arches and how it melts, which helps solidify theories on the origins of plate tectonics and how the continental crust was formed.

[...]Based on their research, University of Liverpool seismologists suggest that over the age of the Earth, the Japan subduction zone alone could transport as much as three and a half times the water contained in all of Earth’s oceans to the mantle. Some of this water gets cycled back out of the mantle, but some gets trapped deep within it.

[...]"These hydrated fault zones can carry large amounts of water, suggesting that subduction zones carry much more water from the ocean down to the mantle than has previously been suggested," Garth said. "This supports the theory that there are large amounts of water stored deep in the Earth."

[...]Based on an analysis of the isotopes of natural gases in the water, scientists believe it to be the oldest isolated water ever studied, at least 1 billion years old and maybe as old as 2.64 billion, slightly younger than the rocks that encased it.* For maybe half as long as the Earth’s entire existence, this water has been sealed away, unexposed to the atmosphere.

The next question: Is it drinkable? The answer: Not really, but a sip won’t kill you. According to an interview in the Los Angeles Times, one of the paper’s authors, Barbara Sherwood Lollar, has tasted it, and it was "terrible," she reports. "It is much saltier than seawater."