ZAP // NightCafe Studio
A team of eth Zurich scientists confirmed that solid Rocha flows inside the Earth, almost 3,000 kilometers deep, solving a mystery of decades on seismic waves.
Earthquakes, volcanic eruptions and continents to the drift remind us that the earth is not a rock ball, but a dynamic and living planet.
Now scientists have discovered something even more surprising in the deep surface: nearly 3,000 kilometers deep, the solid rock is really flowing.Not like melted lavabut like a solid mass that moves slowly over time.
The discovery is the result of a new study, led by Motohiko MurakamiSpecialist in Experimental Mineral Physics at ETH Zurich.
The conclusions of the study, which were presented in a recently published in the Communications Earth & Environmentthey shed a new light on a of the largest geological mysteries on Earth.
During More than five decadesthe scientists were intrigued by a strange region near the border between the mantle and the earth’s core, known as D ”.
Located at about 2,700 kilometers below our feet, this zone has long been challenged explanations. The seismic waves, those triggered by earthquakes, suddenly accelerate when crossing it, as if they found a completely different type of material.
Until now, No one could explain why.
In 2004, Murakami found that the perovskitethe main mineral of the lower cloak of the earth, turns into a new mineral near the D layer ” under extreme pressure and very high temperatures – the so -called “Postperovskite“.
The investigators assumed that This change explained the strange acceleration of seismic waves. But this It was not the full story. In 2007, Murakami and colleagues found new evidence that Perovskite’s phase change alone It is not enough to speed up seismic waves.
Using a sophisticated computational model, they finally discovered something important: depending on the direction to which postperovskite crystals point to, The hardness of the mineral changes.
Only when All mineral crystals point in the same direction In the model is that the seismic waves are accelerated – as can be observed in layer D ”at a depth of 2700 kilometers.
In an unusual laboratory experience at ETH Zurich, Murakami has now proved that post-perovskite crystalsand align in the same direction under huge pressure and extreme temperatures.
For this, the investigators measured the speed of seismic waves in their experience and also managed to reproduce the jump that occurs in layer D ”in the laboratory. We found the last piece of Puzzle“Says Murakami, quoted by.
In a previous study, the Murakami team had already discovered that the interior of the earth due to the presence of a mineral on the border between the earth’s outer iron nucleus and the lower mantled mantle of the melted fluid above it, designated bridgmanitewhich turns into postperovskite.
The flow of the cloak aligns the crystals
The big question is: What makes these crystals align themselves? The answer is that the solid rock of the cloak flows horizontally along the lower end of the earth’s cloak. Investigators had long suspected that this movement should exist, but never managed to prove it directly.
Murakami and his colleagues have now also demonstrated that the convection of the solid rock cloak is present at the border between the nucleus and the earthly cloak, that is, that solid rock, non -liquid, It flows slow but constantly in this depth.
“This discovery not only solves the mystery of layer D”, but also opens a window to the dynamics in the depths of the earth, “explains Murakami.
It’s not just a milestone, but also a turning point. The assumption that solid rock flows has become a theory into certainty. “Our discovery shows that the earth is not only active on the surface, but it is also moving within it,” says the ETHE professor.
With this knowledge, researchers can now start mapping the currents inside the Earth and thus visualizing the invisible engine that drives volcanoes, tectonic plates and perhaps even the magnetic field land.
