A team of scientists has detected the presence of an enormous water reservoir, three times larger than all the oceans combined, located 700 kilometers beneath Earth’s surface.
What if the origin of Earth’s water came from there, from its mantle? That is the question being raised by the researchers behind an incredible discovery. They have found evidence of a gigantic ocean buried more than 700 kilometers below Earth’s surface. And gigantic is not an exaggeration: its volume is believed to be three times greater than all the oceans found on the surface.
This mysterious reservoir is hidden inside a blue rock known as ringwoodite, located deep within Earth’s mantle, the layer of hot rock between the planet’s surface and its core.
According to scientists, its immense size could help explain where Earth’s water came from. The discovery supports a theory suggesting that the oceans gradually seeped out from inside the Earth. Meanwhile, the theory that water arrived mainly through comet impacts is looking a little less convincing.
‘This is tangible proof that Earth’s water came from within,’ said Steven Jacobsen, a researcher at Northwestern University in Illinois and the lead author of the study.
He believes this hidden water may also help maintain the size of the oceans, which has remained relatively stable for millions of years.
A discovery that could explain Earth’s water cycle
To make this discovery, the research team used no fewer than 2,000 seismographs across the United States to study seismic waves produced by more than 500 earthquakes. These waves travel through the Earth, including through the core, and can be detected at the surface.
By measuring the speed of the waves at different depths, researchers were able to determine what types of rock they were passing through. That is how they detected this immense water reservoir, because the waves slowed down when they moved through wet rock: ‘It is a layer of rock with water along the edges between the grains, almost as if they were sweating.’
‘We should be grateful for this reservoir. If it were not there, it would be on the surface of the Earth, and mountain peaks would be the only visible land,’ Jacobsen explained.
Now, researchers hope to gather more seismic data from around the world to find out whether melting in the mantle is common or not. Their findings could eventually help scientists better understand Earth’s water cycle.
