Yes, the oceans are quite large. You wouldn’t want to get lost in one. But did you know that there was a recent discovery of an ocean reservoir that has a volume three-times larger than all the other oceans combined? This finding is making scientists rethink the origins of Earth’s water supply.
The water is actually hidden inside a blue rock called ringwoodite and it resides 700 kilometers below in the Earth’s mantle – the layer of rock between the core and the crust. Most scientists believe that the origin of Earth’s water originated from comets slamming into the Earth in the early stages of its formation. Now, with this discover, scientists are starting to theorize that water oozed out from the center in the early stages of development.
A team at Northwestern University in Evanston, Illinois used 2000 seismometers to study the seismic waves generated by more than 500 earthquakes. It was like listening to the Earth as if it were a ringing bell. By doing this they were able to determine the depth of a reservoir as well as determine what type of rock the underground water was passing through by the rate of speed in which the waves slowed down.
“It’s rock with water along the boundaries between the grains, almost as if they’re sweating,” says Steven Jacobsen of Northwestern University. The idea of the possibility of this layer of ringwoodite came after a study by Graham Pearson who found a diamond that was pushed up by a volcano: a diamond containing evidence of water bearing ringwoodite.
Judging how waves slowed down after being jostled around during earthquakes, Jacobsen hypothesized that there was a large layer of ringwoodite below the surface in the transition zone. After growing ringwoodite, and observing how it interacted with water, he was able to confirm his suspicions. It was the first evidence that there was hydrous rock above the Earth’s core.
“Since our initial report of hydrous ringwoodite, we’ve found another ringwoodite crystal, also containing water, so the evidence is now very strong,” says Pearson
Currently, they only have evidence that the watery rock sits below the surface of the United States but wants to figure out of this layer extends around the entire planet.