There’s an ocean about 400 miles underground that could fill all the oceans in our earth three times over. That’s probably hard to believe. But after decades of theories and research, scientists in July 2014 announced that they had discovered a huge water reservoir in the Earth’s mantle. According to the breathtaking report, this reservoir was immensely big and suggests that the earth’s surface water comes from within. This puts theories of icy comets and others hanging on loose strings.
The interior/inside of the earth, just like that of other terrestrial planets, is divided into chemical layers. The mantle is a layer of the earth that’s located between the crust and the outer core. It is made up of a rocky silicate shell and has an average thickness of 2, 886 km. The mantle constitutes up to 84% of the total volume of the earth.
The study resulting in this finding was conducted by a collective of scientists and geophysicists across the United States and derives its data from USArray, which encompasses hundreds of seismographs that are located throughout the US and that constantly listen to movements within the Earth’s core and mantle. After listening for a couple of years, and conducting lots of sophisticated calculations, the scientists now believe that there’s a huge water reserve hidden in the transition zone between the earth’s lower and upper mantle. This region occupies around 400 – 660 km underground.
As you could imagine, things are a bit hectic that far below your feet. This is not a water reserve that can be accessed like a water well. Make no mistake – the deepest human drilling has ever gotten is just 12km, which is about halfway through the earth’s crust. Nothing else could be done below that point because intense geothermal energy was already melting the drilling equipment. That probably paints the picture that up to 660 km is a long way done. There’s no telling what kind of weird stuff goes on deep down there!
Based on the 2014 findings and associated theory, the mantle is filled with a mineral known as ringwoodite. Under extreme pressure, ringwoodite is understood (through experiments on the surface), to trap water. Based on USArray measurements, convection pushes the mineral deeper down into the mantle. This massive pressure forces the retained water out through a process known as dehydration melting. That is how far the study goes. Scientists will now probably try to establish a link between what happens on the surface with deep-Earth geology. It takes years of painstaking measurements and complex scientific calculations to even get any useful data from these kinds of studies. So understandably, understanding the complicated machine that’s the earth happens at a slow pace. But with each new finding, we are able to predict the future more accurately, and increase our understanding of weather, tectonic activity, climate change, sea levels, etc.