As the tectonic plates of the earth diverge, they draw three times as much water in the planet as previously…
As the tectonic plates of the earth diverge, they draw three times as much water in the planet as previously thought.
This is the result of a new paper published today November 1
4th in the journal Nature. With the help of the natural seismic rumbling of the earthquake subduction zone at Mariana’s dig, where the Pacific plate slides under the Philippine plate, researchers could estimate the amount of water contained in the rocks that are deep underneath the surface. [In Photos: Ocean Hidden Beneath Earth’s Surface]
The finding has major implications for understanding the deep water cycle of the earth, wrote marine geology and geophysics researcher Donna Shillington from the Lamont-Doherty Earth Observatory at Columbia University in an update that accompanies the new paper. Water underground can contribute to the development of magma and can lubricate errors, making earthquakes more likely, wrote Shillington, who was not involved in the new research.
Water is stored in the crystalline structure of minerals, Shillington wrote. The liquid is incorporated into the earth’s crust both when completely new, hot-hot hot plates are formed and when the same plates bend and burst when they slip under their neighbors. This later process called subduction is the only way water penetrates deep into the crust and the mantle, but little is known about how much water moves during the process, wrote Chen Cai, Head of Studies at Washington University in St. Petersburg. Louis and his colleagues in their new paper.
“Before we did this study, all scientists knew that the water had to be carried by the subduction plate,” told Cai Live Science. “But they just did not know how much water.”
The researchers used data collected by a network of seismic sensors located around central Mariana’s Trench in the Western Pacific. The deepest part of the excavation is almost 7 miles (11 kilometers) below sea level. The sensors detect earthquakes and the eclipses of the earthquakes that call through the earth’s crust like a bell. Cai and his team traced how quickly these temblors traveled: A slowdown in speed, he said, would indicate water-filled fractures in rocks and “hydrated” minerals that lock water in their crystals.
The researchers observed such slows deep into the crust, about 18 miles (30 km) below the surface, Cai said. Using the measured velocities, together with known temperatures and pressures found there, the team estimated that the subduction zone draws 3 billion teragrams of water in the crust every million years (a teragram is one billion kilograms).
Sea water is heavy; A cube of this water 1 meter long on each side would weigh 1,024 kilos. But still the amount drawn by subduction zones is small. There are also three times as much water as subduction zones previously estimated to take in, Cai said.
And it raises some questions: The water that goes down must come up, usually in the volcanic eruption’s content. The new estimate of how much water goes down is greater than estimates of the volume of volcanoes, which means researchers lack something in their estimates, researchers say. There is no water in the oceans, “said Cai. This means that the amount of water dragged into the crust and the amount that sprung out would be about the same. That they do not suggest that there is anything about how the water moves through the interior of the earth as a scientist does not yet understand.
“Many more studies must be focused on this aspect,” said Cai.
Originally published on Live Science.