This appeared in US News and Wold Report:
Scientists have discovered vast water reserves near Earth’s mantle, a finding that could reshape our understanding of where Earth’s water came from.
According to a new study by a group of U.S. geophysicists, a reservoir of water three times the volume of all of Earth’s oceans has been discovered inside a layer of blue rock 440 miles deep.
Geophysicist Steve Jacobsen of Northwestern University, who coauthored the study, says it’s evidence the planet’s water bubbled up from somewhere underground.
The water is thought to be trapped in a layer of ringwoodite, a rock with a crystalline structure that acts like a sponge, to attract and trap the hydrogen and oxygen atoms that comprise water.
While the presence of this layer of ringwoodite hasn’t be confirmed, there is mounting evidence that it exists. A chunk of diamond carried to Earth’s surface in a volcano earlier this year had a piece of ringwoodite inside.
Scientists used 2,000 seismometers to track the vibrations generated by earthquakes across the planet. The waves appeared to be propagating through saturated rock, rather than dry material, which gave scientists an idea of the size of the reservoir.
The scientists are trying to find out whether this reservoir layer extends around the whole planet. In the meantime, the results of the study thus far have been published in the journal Science.
I love this stuff.