Two strange formations, located about 2000 kilometers under our feet, confused scientists and turned the traditional ideas about the inner structure of our planet.
Two formations the size of a continent and a height of more than Everest have haunted scientists for several years. They were discovered back in the 1970s, after the seismic tomography method became available to science, allowing scientists to study the interior of the planet. Two formations, which experts humorously call "bubbles", are located under the earth's mantle, just above the outer core. Stone structures, as scientists suspect, have a very high temperature, and it is in them that the clue to the past of our planet and even the origin of life on it lies. After all, according to geologists, life on Earth appeared, among other things, due to tectonic plate movements. And as geologists suspect, it is two giant "bubbles" that may be responsible for tectonic plate shifts, as well as a number of other processes, including volcanic activity.
One of the strange formations is under the Pacific Ocean, and the other is under Africa and part of the Atlantic. As the researchers say, they look like giant mountain ranges that delimit the mantle and core of the Earth about halfway to its center. "Something strange is happening in these places," says geology professor Ed Garnero of the University of Arizona. "For unknown reasons, seismic waves slow down as they pass through these formations." However, this is the only thing that scientists know for certain: “bubbles” still remain a mystery to them in almost everything.
Today, the main question of scientists for "bubbles" is the question of their density. What are they made of - from dense and heavy, still unknown rock, or from porous lava stone, like the earth's layers above? Alas, researchers still cannot find out for quite objective circumstances: today, it is more difficult for scientists to study the deep layers of the planet than to get to know Venus or Mars. “We know less about what is happening under our feet than about what is happening in the sun,” complains researcher Paula Colmeyer of University College London. Until the question of the density of the "bubbles" is answered, scientists will not be able to test many of their assumptions - for example, the assumption that these strange formations are responsible for the emergence of active volcanoes that form chains of islands, such as Hawaii, and in the past,millions of years ago, they were responsible for several super-eruptions that nearly erased all life from the face of the Earth.
Many are aware of ocean tides, but few are aware that the same cosmic forces that affect the oceans also affect the earth's crust. Like the ocean, it also rises and falls twice a day, and its fluctuations in some places reach 40 centimeters. According to the observations of scientists, over the strange "bubbles" vibrations are not at all the same as in the rest of the planet. Here they are noticeably stronger. This discovery made it possible for scientists to chart a new possible direction for the study of bubbles. "The ebb and flow of the solid earth is very sensitive to the density of matter," says Harriet Lau, a research fellow at Harvard University. Based on this feature, scientists began to study the density of "bubbles" by measuring the strength of vibrations, including after earthquakes. The results allowed, in particular,Field Colmeyer and her team suggest that the "bubbles" are possibly significantly less dense than the surrounding matter. However, while these studies are at the very beginning, and, as the scientists themselves admit, at the present time they cannot draw any conclusions with complete confidence.
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A few months ago, graduate student Maria Tsekhmistrenko from Oxford University presented a map of a "bubble" located under Africa, entirely compiled using seismic tomography. The project to track the structure of the bubble with seismic sensors installed on the ocean floor in the Madagascar region lasted several months. As a result, a 3D map of the bubble was drawn on the image taken by Tsekhmistrenko and her team. On it, it looks like a tree, whose wide roots go into the depths of the earth, and numerous branches stretch to the surface, reaching it exactly at those points where active volcanoes are located. "At first we didn't even believe what we saw!" - says Tsekhmistrenko. However, for all the importance of the work done, from it, again, it is still impossible to draw unambiguous conclusions aboutto what extent "bubbles" stimulate volcanic activity on the planet. However, scientists are convinced that they cannot do without their influence.
However, scientists are determined to solve the riddle of the bubbles. “They are one of the largest formations inside the Earth, and we still don't know what they are or where they came from,” says geologist Ved Lekis of the University of Maryland. "Their mystery is their main attraction." Scientists are confident that the study of "bubbles" and their influence on earth's volcanoes will be long and difficult, but they are no less confident in their future victory over the unknown and in the upcoming discovery of the mystery of the mysterious "bubbles".
Author: Queen's Bolonka