Hidden water world: Earth’s massive underground ocean revealed
Beneath the Earth's surface lies a vast ocean, which is three times larger than all the oceans on the planet. However, it is not a liquid.
Scientists have identified a gigantic ocean hidden hundreds of kilometres beneath the Earth's surface. According to researchers, this underground water reservoir is three times larger than all the oceans on our planet combined. This discovery could change our understanding of the Earth's water cycle.
Underground ocean in the transition zone
Researchers have long speculated about the existence of such an ocean located between the upper and lower mantle, in the so-called transition zone, at a depth of about 400 to 650 kilometres. Geophysicist Steve Jacobsen from Northwestern University and seismologist Brandon Schmandt from the University of New Mexico were the first to provide evidence for the existence of this structure in 2014.
The underground ocean extends beneath the United States at a depth of around 650 kilometres. Scientists determined this using seismographs deployed across the USA, which detected seismic waves from over 500 earthquakes. These waves accelerated in the transition zone, suggesting the presence of a vast water reservoir.
Water trapped in minerals
The underground ocean is neither in liquid form nor ice. The water is trapped in the molecular structure of minerals in the Earth's mantle, specifically in ringwoodite, which is a form of olivine. Ringwoodite contains between 2.5 to 3% by weight of water.
This discovery may impact the theory of the origin of water on Earth. It has been thought that water came from asteroids or comets that struck the Earth billions of years ago. Research by Jacobsen and Schmandt suggests that water may originate from within our planet.
Underground oceans in the solar system
Similarly fascinating discoveries concern Ceres, the dwarf planet between Mars and Jupiter. Data analysis from the Dawn probe indicates that an ocean may be rich in organic materials beneath its surface. Studies suggest that these substances could be endogenous and perhaps even conducive to forms of life. As a water-rich body, Ceres is an intriguing target for further research.
Mars, known for its previous oceans, also hides underground water reservoirs. The InSight mission showed that the Red Planet has underground water that could cover the entire planet with an ocean 1 to 2 kilometres deep. This discovery sheds new light on the possibility of life on Mars and its ancient climatic conditions, which could have been favourable for its development.
Similar signs of the existence of subsurface oceans are found on Uranus's moon, Ariel. Observations from the Webb Telescope have revealed rich deposits of CO2, indicating geological processes within the moon. This suggests that Ariel may have a hidden ocean that supplies material to the surface through cracks in the ice crust, making it another target for space exploration.
