In this representation of the underground images, seismic waves from earthquakes in the southern hemisphere are sampled from the ULVZ structure along the Earth’s core-mantle boundary and recorded by sensors in Antarctica. Figure courtesy of Drs. Edward Garnero and Mingming Li at Arizona State University.
Scientists have created a high-resolution map of the geology beneath Earth’s southern hemisphere, revealing what appears to be an ancient seafloor.
For decades, scientists have pondered and debated what probably lies beneath our feet. Understanding what lies below the surface is vital to studying everything from volcanic eruptions to variations in Earth’s magnetic field, which shields us from solar radiation in space.
In particular, we’re talking about the most anomalous and enigmatic layer of Earth’s deep interior: the boundary between its fiery liquid outer core and the solid mantle that surrounds it, the reports the Washington Post.
Interestingly, this latest study comes almost two months after another team of scientists published a study that revealed a fifth distinct layer of Earth deep in the core, which could help us understand its magnetic field.
In that study, the scientists relied on seismic data from earthquakes. When a large earthquake occurs, the resulting shock waves, or seismic waves, can bounce from one side of the Earth to the other like a ping-pong ball.
Using this information, the team found a new way to sample the very center of Earth’s inner core, proving that a distinct fifth layer of Earth exists.
The geology beneath the southern hemisphere
In the current study, published in the Science Advances magazine on April 5, 2023, University of Alabama geologist Samantha Hansen and her colleagues used 15 monitoring stations buried in the Antarctic ice to map seismic waves from earthquakes over a three-year period.
The way those waves move and bounce reveals the composition of the material inside the Earth. Because sound waves move slower in certain areas, they are called ultra-low-velocity zones (ULVZs).
The measurements obtained revealed a strange boundary layer, nearly 2,000 miles deep. “Analyzing [thousands] From seismic recordings from Antarctica, our high-definition imaging method found thin anomalous zones of core-mantle boundary (CMB) material everywhere we probed,” says geophysicist Edward Garnero of Antarctica State University. Arizona.
The thickness of the material varies from a few kilometers to [tens] of kilometers. This suggests that we are seeing mountains at the core, in some places up to five times higher than Mount Everest.”
“That’s five times the size of Mount Everest,” Hansen said. The highest peak on Earth was most recently measured at 29,031 feet or nearly 5.5 miles. “You have this dramatic topography, some lower and some very high.” That irregular structure, along with geological patterns, suggests that the layer is made up of material at the core-mantle boundary, the paper’s authors conclude.
Evidence suggests that at subduction zones, where one tectonic plate dips beneath another, the ancient ocean floor is pushed down and falls to the bottom of the mantle over hundreds of millions of years.
According to the researchers, these ULVZs are likely oceanic crust buried for millions of years, according to Scientific alert.
