The vastness of Earth’s oceans can be quite daunting. Imagine, however, discovering a hidden water reservoir beneath the Earth’s surface, potentially containing three times the water of all our oceans. Intriguing, isn’t it?
This concealed reservoir isn’t in a liquid state. It resides 400 miles underground within a mineral known as ringwoodite, part of the Earth’s mantle.
Ringwoodite acts like a sponge, encapsulating water in its crystal structure in a unique form that’s neither liquid, solid, nor gas — something fundamentally different at the molecular scale.
In 2014, researchers from Northwestern University in Illinois made this groundbreaking discovery using seismometers to analyze earthquake waves traversing the Earth.
These seismic waves revealed that this water wasn’t near the surface but encased in certain kinds of rock deep below.
Steve Jacobsen, a geophysicist on the research team, explained ringwoodite’s distinctive ability to absorb hydrogen and contain water under extreme pressure and heat.
“The ringwoodite is like a sponge, soaking up water, there is something very special about the crystal structure of ringwoodite that allows it to attract hydrogen and trap water,” said Jacobsen.
“This mineral can contain a lot of water under conditions of the deep mantle.”
Their research also showed that these waves weren’t confined to the surface, but traversed deeper into the planet’s core.
By analyzing the velocity and depth of these waves, scientists identified the rocks containing the water, ultimately pinpointing ringwoodite.
This mineral can hold up to 1.5 percent water. If the ringwoodite beneath Earth’s surface possesses just one percent water in its composition, it could mean it retains three times more water than all the oceans combined.
The significance of this discovery lies in its potential to help scientists understand Earth’s formation, supporting the theory that Earth’s water originated internally rather than from external celestial bodies like asteroids or comets.
Jacobsen highlighted, “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.”
Jacobsen and his team aim to determine if this water-bearing layer encircles the entire Earth in the future.