Earth's largest water reservoir located inside Earth’s mantle

Earth’s largest water reservoir might be located deep inside the Earth’s mantle. This was revealed by a study published in the journal Science on 13 June 2014.

The study was conducted by the Northwestern geophysicist Steve Jacobsen and University of New Mexico seismologist Brandon Schmandt.

The study is the first to provide direct evidence that there may be water in the area of the mantle known as the transition zone – the layer between lower mantle and upper mantle.

The findings will aid scientists in understanding how the earth formed, what its current composition and inner workings are and how much water is trapped in mantle rock.

About the discovery

In the study, geophysicists found that deep pockets of subterranean magma indicating presence of water were located about 643 km beneath North America. The water is not in a liquid, ice or vapour form. The fourth form of water is trapped inside the molecular structure of the minerals in the mantle rock.

The discovery found the evidence that melting may occur about 643 km deep in the Earth. H2O, that is, water were stored in mantle rocks where the mineral ringwoodite is present.

The discovery suggest water from the Earth’s surface can be driven to such great depths by plate tectonics which eventually caused partial melting of the rocks found deep in the mantle.

Scientists have long speculated that water is trapped in a rocky layer of the Earth’s mantle located between the lower mantle and upper mantle, at depths between 400 km and 660 km.

As per the analysis of researchers, if just one per cent of the weight of mantle rock located in the transition zone is H2O, it would be equivalent to nearly three times the amount of water in our oceans.