Les ondes sismiques nous permettent d'imager la structure du manteau profond. © 3D motion, Adobe Stock

Journey to the center of the earth: the inner core is not fixed!

the earth core occurs from a depth of 2,900 km. This corresponds to about 17% of volume Building the globe…” data-image=”https://cdn.futura-sciences.com/buildsv6/images/midioriginal/8/4/f/84ff7edce5_123534_terre-apollo8.jpg” data-url=”https : / /news.google.com/planete/definitions/structure-earth-earth-4725/” data-more=”Read more”>Earthit is located in its central part and is divided into two parts: an outer core liquid and an inner core (or nucleus) crystals and amorphous solids
Scaled…” data-image=”https://cdn.futura-sciences.com/buildsv6/images/midioriginal/e/6/8/e6888a7dfb_82227_solide.jpg” data-url=”https://news.google .com/sciences/definitions/solid-chemistry-15332/” data-more=”Read More”>Celebration.

The outer core consists essentially of about 80 to 85% iron very hot in The melting point of water, which is the temperature at which ice melts…” data-image=”https://cdn.futura-sciences.com/buildsv6/images/midioriginal /7/d/0 /7d0df59f3c_82086_fusion .jpg” data-url=”https://news.google.com/sciences/definitions/physics-fusion-15305/” data-more=”Read more”>merger. It is stirred by a movement of convection of thermal origin (due to the cooling of the Earth) and thanks to it, the Earth’s magnetic field is created. the inner core, it is formed by progressive crystallization of the outer core and resembles a very hot and dense sphere the size of . When Pluto was discovered by Clyde Tombaugh in 1930, it was thought to be the ninth planet in the solar system. But from the late 20th century, other fairly similar objects were discovered, including Eris, which it marginally surpassed. It appeared quickly…” data-image=”https://cdn.futura-sciences.com/buildsv6/images/midioriginal/0/5/d/05dfff5cf7_75287_plutonnh-2307-01-stern-02c-pluto- nat- color.jpg” data-url=”https://news.google.com/sciences/definitions/universe-pluto-3691/” data-more=”Read more”>Plutoalso composed made of iron but solid. On the other hand, its exact nature and who movements it has been discussed for decades and makes the research areas of geophysics and geochemistry very active.

Techniques for observing and examining the core

One of the problems with studying the Earth’s inner core is that it cannot be seen, forcing researchers to use tricks and indirect methods to obtain information about its nature and dynamics. With this in mind, researchers Wei Wang and John Vidale – scientists at USC Dornsife – used data from the Large aperture seismic array (Lasa), a facility for networked seismometer systems from the USA Air Force in Montana, which allows acquisition and increase the sensitivity of detection earthquake and explosions.

This type of data is obtained using special signal processing techniques Digital B. Beamforming, which suppresses noise and thus improves the signal-to-noise ratio.

Using a new beamforming technique developed by Vidale, the two researchers analyzed waves generated by Soviet underground nuclear bomb tests at Milrow in 1969 and Cannikin in 1971 under Amchitka Island. They used the same method for the period between 1971 and 1974 in the arctic archipelago of Novaya Zemlya.

How does the core of the earth behave?

In their latest study, recently published in scientific advancesUsing this seismic data, Wang and Vidale determined that the inner core motion had changed direction over the six-year period from 1969 to 1974, rotating the underrotation by at least a tenth of a degree per year. More specifically, observations indicate that the inner core spun slightly more slowly from 1969 to 1971, and then began to move in the opposite direction from 1971 to 1974.

This observation is quite unexpected and first surprised researchers Wang and Vidale. Having an oscillating inner core was a model that had been thought of and existed, but the scientific community was very divided as to the viability of this theory. In addition, some scientists claim that this pattern also explains the observed sharp six-year oscillation in day length (plus or minus 0.2 seconds over six years) that has been observed regularly in recent decades.

It turns out, therefore, that the inner core is not fixed at all, as we thought for a long time, but that it moves and vibrates under our feet. However, the era of Underground nuclear tests is a thing of the past, meaning scientists have to use seismic data from Earth activity, which despite recent advances in instrumentation is relatively less accurate.

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