Changes in the Earth’s outer core

How can two earthquakes, just 20 years later, relate and help us understand What happens in the center of the earth? A study published last April in the journal answers this question Nature, Earth and Environment Communications, by geologist Ying Zhou, of Virginia Tech’s Department of Earth Sciences. And all thanks to one Imperceptible anomaly I’ve never seen him before.


Earthquakes reveal changes in the outer core

The Study geologist Ying Zhou It gives us an important and unprecedented glimpse into what is happening at the center of the Earth. Until now, scientists have not been able to Monitor these changes livethose inherent in the convection of the outer core and the effects on the Earth’s magnetic field.

Professor Ying Zhou studied two seismic phenomena in particular. The first happened in May 1997 in Kermadec Islands, in the Pacific Ocean, while the second hit the same spot a little over twenty years later (in September 2018). Therefore, seismic waves come from exactly the same region which is expected to be of equal velocity. However, this is not the case.

Real-time recorded data prove the existence of one A slight, almost imperceptible anomaly between the two seismic events: The SKS waves of the second earthquake moved at a faster speed (about one second) than those recorded at the same location twenty years ago. With “SKS” we refer to the three phases of a seismic wave: first, it passes through the mantle as a shear wave (S), then it passes through the outer core as a pressure wave (K), and finally, it returns again as a cut wave (S).

Given this pattern, if the seismic wave travels at a certain speed, then it means that the outer core has a specific intensity in that region. And if this speed changes over time, it means that The density of the outer core itself changed“Something has changed along the path of that wave, so it can now go faster,” says Professor Ying Zhou.

What happens in the center of the earth

Thanks to the data collected by Ying Zhou for the first time, we have concrete evidence of changes taking place in the outer core of the planet. So far, every study or observation has been done It is based solely and exclusively on theorieswithout any evidence against it.

With her study, the professor wanted to reach exactly this conclusion. This seemingly insignificant second of the difference in speed between two earthquakes, which occurred years later at the exact same point, gives us Calculated for the first time (numerically) of how the activity of the Earth’s core has changed. As a result, it becomes a starting point for gathering more data about the change in the Earth’s magnetic field.

The Pregnancy cloak movements, or the thick layer of rock under the Earth’s crust that covers the outer core, generates flows of liquid metal in motion and it is this activity that in turn allows the Earth’s magnetic field. Only in theory have so far been speculated changes in the strength and direction of the magnetic field as a result of changes in fluxes at the center of the Earth, but today we know for the first time that they can Gather direct evidence for this phenomenon.

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