Scientists, after decades of investigation have uncovered a vast reservoir of water deep below the surface of Earth, 400 miles underneath the US. The massive reservoir is estimated to be three times the volume of all of the oceans on the surface of Earth.
Steven Jacobsen of Northwestern University in Evanston, Illinois, along with University of New Mexico seismologist, Brandon Schmandt was the first to provide evidence that the Earth's 'transition zone' – the region between the lower and upper mantle, contains water.
The water is trapped inside a blue rock and a mineral called ringwoodite, which is 700 kilometres underground in the mantle – a layer of hot molten rock sandwiched between Earth's surface and its core.
The discovery provides good evidence that the Earth's water came from within, according to Jacobsen. The finding also suggested that the interior ocean could work as a buffer to maintain the oceans on the Earth's surface at relatively same size for millions of years.
Previously, geologists believed that water on the earth may have been produced due to comets, but the recent finding suggests that the vast oceans could have gradually come out of the interior of the early Earth.
Jacobsen and Schmandt believe that findings will help scientists to determine how the Earth formed, its present composition and the amount of water that is actually trapped inside mantle rock.
"Geological processes on the Earth's surface, such as earthquakes or erupting volcanoes, are an expression of what is going on inside the Earth, out of our sight. I think we are finally seeing evidence for a whole-Earth water cycle, which may help explain the vast amount of liquid water on the surface of our habitable planet. Scientists have been looking for this missing deep water for decades," The Guardian quoted Jacobsen.
For their study, Jacobsen and his team used 2000 seismometers to study the seismic waves produced by over 500 earthquakes. The waves move throughout the interior of the Earth including its core, which can be experienced at the surface.
"Melting of rock at this depth is remarkable because most melting in the mantle occurs much shallower, in the upper 50 miles. If there is a substantial amount of H2O in the transition zone, then some melting should take place in areas where there is flow into the lower mantle, and that is consistent with what we found," Daily Mail quoted Schmandt.
Schmandt and Jacobsen's finding was based on a previous discovery reported in March in the journal Nature, in which scientists uncovered a piece of ringwoodite within a diamond that cropped up from a volcano 400 miles deep in Brazil.
The small piece of ringwoodite, which is the only sample from within the Earth was found to contain some amount of water trapped in solid form. This discovery led the researchers to farther their studies on trapped water.
If one percent of the weight of mantle rock in the transition zone is water, it would be equivalent to almost three times the amount of water in our oceans, explained the researchers.
The details of the findings have been published in the journal Science.