In earthquake-prone subduction zones where tectonic plates dive beneath each other, vast amounts of seawater are drawn into the interior of the planet, a new study found.
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As the tectonic plates of Earth dive beneath each other, they throw three times as much water into the interior of the planet as previously thought.
These are the findings of a new newspaper that was published today (November 1
The find has major implications for understanding the Earth's deep water cycle, said Marine Geology and Geophysics researcher Donna Shillington of the Lamont-Doherty Earth Observatory at Columbia University, along with the new paper. Underground water can contribute to the development of magma and smear errors and make earthquakes more likely, wrote Shillington, who was not involved in the new research.
The Deep Water Cycle
Water is stored in Shillington wrote the crystalline structure of minerals. The liquid is incorporated into the earth's crust when brand-new, rippling oceanic plates form and when the same plates bend and break as they crunch beneath their neighbors. This latter process, called subduction, is the only way that water penetrates deep into the crust and mantle, but little is known about how much water moves during the process, study lead director Chen Cai of the University of Washington said Washington University in St. Louis and his colleagues in their new paper report.
"Before we did this study, every researcher knew that water had to be carried down the subducting plate," Cai told Live Science. "But they just did not know how much water."
Researchers used data collected from a network of seismic sensors positioned around the central Marianas Trench in the western Pacific. The deepest part of the ditch is just under 11 kilometers below sea level. The sensors detect earthquakes and the echoes of earthquakes that ring like a bell through the earth's crust. Cai and his team tracked how fast these Zittlers were traveling: a slowing of speed indicated water-filled breaks in rocks and "hydrated" minerals blocking water in their crystals.
Water is missing
The researchers observed such slowdowns deep into the crust, about 30 kilometers below the surface, Cai said. From the measured velocities and the known temperatures and pressures found there, the team calculated that the subduction zones draw 3 billion teragrams of water every millennium into the crust (one teragram is one billion kilograms).
Seawater is heavy; A cube of this water, which is 1 meter long on each side, would weigh 1,024 kilograms. Nevertheless, the amount taken up by subduction zones is insane. It's also three times as much water as it was previously assumed that subduction zones were recorded, Cai said.
And that raises some questions: The water that falls down must emerge, usually in the contents of volcanic eruptions. The new estimate of how much water goes back is greater than the estimate of how much is expelled from volcanoes. This means that the scientists are missing something, the researchers say. There is no water in the oceans, said Cai. This means that the amount of water that is drawn into the crust and the amount that spouts back out are about the same. The fact that this is not the case indicates that there is something in the way water flows through the interior of the earth, something scientists do not yet understand.
"Many more studies need to focus on this aspect," said Cai.
Originally published on Live Science.