Researchers may have found the planet’s largest water reservoir. via phys.org:
Researchers from Northwestern University and the University of New Mexico report evidence for potentially oceans worth of water deep beneath the United States. Though not in the familiar liquid form—the ingredients for water are bound up in rock deep in the Earth’s mantle—the discovery may represent the planet’s largest water reservoir.
The presence of liquid water on the surface is what makes our “blue planet” habitable, and scientists have long been trying to figure out just how much water may be cycling between Earth’s surface and interior reservoirs through plate tectonics.
Northwestern geophysicist Steve Jacobsen and University of New Mexico seismologist Brandon Schmandt have found deep pockets of magma located about 400 miles beneath North America, a likely signature of the presence of water at these depths. The discovery suggests water from the Earth’s surface can be driven to such great depths by plate tectonics, eventually causing partial melting of the rocks found deep in the mantle.