In what seems like a scene from Jules Verne's "Journey to the Center of the Earth," scientists say earthquake faults zones deep under the sea may be taking ocean water into the upper mantle, according to a new study that provides evidence of large subterranean bodies of water underneath our very feet.
The study, which was published in the online journal Geology, used seismic modeling techniques to gather and analyze data on earthquakes that occur deep underground.
An area where a tectonic plate is forced beneath another is called a subduction zone. Scientists from the University of Liverpool, say these zones trap water in the planet's upper mantle. Japan's subduction zone alone could take in around three and a half times the amount of water available in all of the world's oceans. Granted, the team estimates that the amount of time this would have taken involves almost the entire history of the Earth.
"This order-of-magnitude increase in the estimated H2O flux in this arc implies that over the age of the Earth, the equivalent of as many as 3.5 present-day oceans of water could be subducted along the Kuril and Izu-Bonin arcs alone," said the research team. "These results offer the first direct measure of the lower lithosphere hydration at intermediate depths, and suggest that regassing of the mantle is more vigorous than has previously been proposed. "
After checking the data on earthquake seismic waves, the researchers were able to find that earthquake fault zones had low seismic velocities. These low velocity areas were often fault zones that were around 1 to 2 kilometers wide. The slower moving seismic activity was attributed to the presence of serpentinite, a mineral known to contain water. While some of the water is eventually released during tectonic plate activity, a large amount of water is also transported deeper into the surface and is eventually stored in large underground bodies of water.
The new study sheds new light on how the Earth's mantle changes over time. Moreover, the data gathered by the team may also lead to more answers about the mysteries of the mechanisms of plate tectonics.
