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Earth Is Eating Its Own Oceans

As Earth’s tectonic plates dive underneath each other, they drag three times the amount of water into the planet’s interior as recently thought.

Those are the after studies of a new paper published in the diary Nature. Using the natural seismic rumblings of the quake inclined subduction zone at the Marianas Trench, where the Pacific plate is sliding underneath the Philippine plate, scientists could assess how much water gets incorporated into the rocks that plunge far beneath the surface.

The find has major repercussions for understanding Earth’s deep water cycle, wrote marine geology and geophysics researcher Donna Shillington of the Lamont-Doherty Earth Observatory at Columbia University in an op-ed accompanying the new paper. Water underneath the surface of the Earth can contribute to the formation of magma and can grease up faults, making quakes more probable, wrote Shillington, who was not associated with the new research.

Water is stored in the crystalline structure of minerals, Shillington added. The fluid gets consolidated into the Earth’s crust both when new, steaming oceanic plates shape and when similar plates curve and split as they crush under their neighbors. This latter procedure, called subduction, is the only way water penetrates deep into the crust and mantle, however, little is known about how much water moves amid the procedure, study leader Chen Cai of Washington University in St. Louis and his associates wrote in their new paper.

The analysts used information picked up by a network of seismic sensors situated around the central Marianas Trench in the western Pacific Ocean. The deepest part of the trench is almost 7 miles underneath ocean level. The sensors distinguish tremors and the echoes of quakes ringing through Earth’s crust like a chime. Cai and his team tracked how quick those temblors traveled: A slowdown in speed, he stated, would demonstrate water-filled cracks in rocks and “hydrated” minerals that lock up water within their crystals.

The scientists observed such logjams deep into the crust, around 18 miles underneath the surface, Cai said. Using the deliberate speeds, alongside the known temperatures and pressures found there, the team computed that the subduction zones pull 3 billion teragrams of water into the crust at regular intervals.

Seawater is heavy; a 3D shape of this water 1 meter long on each side would weigh 1,024 kilograms. Yet at the same time, the sum pulled somewhere near subduction zones is staggering. It’s likewise three times the amount of water as subduction zones were recently assessed to take in, Cai said.

Also, that brings up several questions: The water that goes must come up, usually in the contents of volcanic emissions. The new estimate of how much water is going is bigger than computations of what amount is being emitted by volcanos, which means researchers are missing something in their assessments, the scientists said. There is no missing water in the seas, Cai said. That implies the amount of water hauled into the crust and the amount gushed back out should be about equivalent. The fact that they don’t propose that there’s something about how water travels through the inside of Earth that researchers don’t yet get it.

“A lot more investigations need to be centered around this perspective,” Cai said.

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