[Trending News] Giant structures inside the earth are older and mysterious than thought

A new study on the huge structures in the form of “island”Located near the Nucleus of the Earth brought surprising revelations: besides being extremelythey can change current understanding of the earth's cloak.

These formations are situated below Africa and the Pacific Ocean, in the deepest part of the terrestrial cloak, involving the nucleus of the planet. Together, they occupy between 3% and 9% of the total volume of the earth.

Without the possibility of direct observation of the terrestrial nucleus, scientists use technique known as seismic tomographywhich analyzes waves generated by earthquakes to create mapping of the interior of the planet. These waves propagate at different speeds depending on the density of the materials that cross, allowing the identification of underground structures.

In the 1970s, they were discovered Two large anomalous formations known as Low Shear Speed ​​Provinces (LLSVPS). In these regions, seismic waves move more slowly than in the rest of the lower cloak, indicating that these “blobs“, As they are nicknamed, have different composition and temperature.

“We have known for years that these islands have been located on the border between the mantle and the nucleus of the earth and that seismic waves slow down in this region“Explains Arwen Deuses, co -author of the study and researcher at the University of Utrecht (Netherlands), in a statement. “This slowdown occurs because LLSVPS are warmerjust as a person runs less fast in the heat than in the cold. ”

Under Africa, the structure called “Award”It has about 800 kilometers highor equivalent to 90 times Mount Everestexplains the Iflscience.

“No one knew exactly what they are madeif they were temporary phenomena or if they were there millions, perhaps billion years ago, ”adds Deuses. These masses are surrounded by Subduced tectonic plate remainswhich sank from the earth's surface to approximately Three thousand kilometers in depth.

Unknown origins

• There is still no consensus on the origin of these formations;
• As they are denser than the cloak around, it is believed to be composed of different material, But its exact composition remains unknown;
• One of the main hypotheses suggests that they are accumulations of underduced oceanic crust over billions of years. Another intriguing theory proposes that Be fragments of an old planet;

The hypothetical planet Theaia would have collided with the earth about 4.5 billion yearslaunching debris that formed the moon. Studies indicate that parts of Theia's cloak, denser, could have mingled with the terrestrial interior and survived throughout the ages.

To better investigate these structures, scientists adopted a new approach. “We included information about the 'damping'seismic waves, that is, the amount of energy lost while crossing the earth, ”explains SUJANIA Talavera-Soza, also from the University of Utrecht.

“Against our expectations, we discover little damping in LLSVPs, which makes the waves there much more audible. On the other hand, in the region where the subduked tectonic plates are, The waves are more softened.”

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What does this mean to the geology of the earth?

Researchers believe that the LLSVPS grain size is an essential factor for their formation. “Subduced tectonic plates have small grainsbecause they recrystallize as they sink into the cloak. This creates many borders between the grains, making more seismic energy dissipate“Explains Ulrich Faul of MIT. “Like LLSVPS show little dampingthis indicates that they have much larger grains. ”

This feature suggests that These masses are old and relatively rigid structuresnot actively participating in the convection of the cloak, a process that moves the internal material of the earth. This also suggests that The cloak is not as well mixed as thought. “After all, LLSVPs need to be able to survive this convective flow in some way,” says Talavera-Soza.

If confirmed, This discovery can change the understanding of formation of volcanoes and mountains. “The earthly cloak is the engine that drives these phenomena“Gods states. “For example, we believe that Mantelian feathersbubbles of hot material that rises from the deep interior of the earth as in a lamp lamp, originate at the edges of these formations. ”

Although what exactly is these structures is still a mystery, new research on the earth's internal oscillations can bring answers. Fortunately, it will not be necessary to expect new earthquakes for this: seismographic data collected since the 1970s can provide valuable information.

The study was published in Nature.