Everyone is familiar with the concept of finding sunken treasure on the ocean floor. Now scientists may have discovered an ancient ocean floor that is itself a kind of geological reserve. Using seismic measurements taken over three years in Antarctica, the research team found that millions of years ago the seafloor moved deeper toward the Earth’s center, creating a relatively large area that surrounded the Earth’s center. I concluded that it landed as a thin layer. The researchers say the findings could have implications for our understanding of how heat escapes from the core, or how volcanic eruptions bring marine material back to the surface.
When University of Alabama (UA) geoscientist Samantha Hansen and her team set up 15 seismographs in Antarctica in 2012, they used waves from earthquakes around the Earth to create the I was interested in creating images of mountains buried beneath. That work, which lasted three years, was successful and led to several papers, but data showed that anomalous energies appeared after waves from earthquakes passed through the core mantle boundary (CMB). Hansen and her colleagues began to investigate further.
The CMB lies approximately 2,000 miles (3,219 km) below the surface. There, the researchers found that seismic waves slow down as they hit certain layers about 3 to 25 miles (40 km) deep. The slowing of waves through this region has characterized it as an ultra-low velocity zone (ULVZ).
“After analyzing thousands of seismic records from Antarctica, our high-resolution imaging method showed the presence of material in the CMB everywhere we surveyed,” said Edward Garnero, professor in the Department of Earth and Space Exploration at Arizona State University. We found a thin anomalous zone.” in this study. “The thickness of this material varies from a few kilometers to tens of kilometers, which suggests that mountains are visible in the core at locations five times higher than him on Mount Everest.”
From the way seismic waves slowed down when they hit the ULVZ, researchers concluded that it’s composed of material from the ancient ocean floor that was pushed out into the Earth’s mantle over hundreds of millions of years. Such material is much denser than the liquid rocks that make up the mantle, and slows seismic waves to the extent revealed by the data.
Measurements of the ULVZ have previously been made in patchy regions, but the data from this study suggest that the ULVZ may surround the entire core of the Earth.
“Seismic surveys like ours are providing the highest-resolution images of our planet’s internal structure and discovering that this structure is much more complex than once thought.” The study provides important links between the shallow and deep structures of the Earth and the holistic processes that move it.”
The research was published in a journal, scientific progress.
Source: University of Alabama
