Indo-Asian News Service
16. November 2018 10:10 am
According to a seismic study, the earth hauls about three times more seawater than previously estimated, which has a significant impact on global water cycle.
The results showed that the loss of seawater is due to the slow-motion collisions of tectonic plates under Mariana Trench, the deepest sea ditch in the world.
In the ditch, the western plate of the Pacific Ocean slips under Mariana's plate sinking deep into the mantle as the plates slowly converge.
"People knew that subduction zones could bring water down, but they did not know how much water," said lead author Chen Cai of Washington University, St. Louis.
"This research shows that sub-zones carry far more water into the deep interior of the Earth many miles below the surface than previously thought," added Candace Major, director of the department Ocean Science of the National Science Foundation.
For the study published in the journal Nature, the team over a year heard the rumbling of the earth – from ambient noise to actual earthquakes – with a network of 19 Passive Seabed seismographs scattered across the Mariana Trench, along with seven island seismograph.
They found that seawater on the plate collides and flexes into the crust and upper mantle along the fault lines that permeate the plate area. Then it is included.
Under certain conditions of temperature and pressure, chemical reactions force the water into a non-liquid form, as hydrous minerals – wet rocks – trap the water in the geological plate in the rock.
Then the plate creeps ever deeper into the earth's mantle and brings the water with it.
The seismic surveys show that the area of hydrated rock at the Mariana Trench extends nearly 20 miles (32.2 km) below the seafloor.
For the Mariana Trench region alone, four times more water subducts than previously calculated. These properties can be extrapolated to predict conditions among other ocean trenches worldwide.
Scientists believe that most of the water that flows down the ditch returns as water vapor from the earth into the atmosphere when volcanoes erupt hundreds of miles away.
But with the revised estimates of the water, the amount of water that enters the earth seems to significantly exceed the amount of leaking water, the researchers said.