? “It carries a deeper secret.” What did the seismic waves reveal in the center of the Earth
Kenneth Chang: Geology books almost unanimously agree that the Earth's diagram shows 4 well-defined layers / Image: nytimes (nytimes)
Geology books are almost unanimous that the Earth's diagram shows 4 well-defined layers. This is what Kenneth Chang, science and technology editor of the British newspaper "The New York Times", began his article by saying: "The Earth's core seems to hold a deeper secret."
The science and technology editor of the British newspaper "The New York Times" Kenneth Chang said that geology books are almost unanimous that the diagram of the Earth shows 4 well-defined layers.
Zhang began his article in the "New York Times" by saying: "It seems that the core of the earth holds a deeper secret." He said that the first layer of the planet's layers is a thin outer shell of rocks, which we live on and is called the crust.
And he added that the second layer is the mantle, where rocks flow a very viscous liquid that drives the movement of continents and the lifting of mountains.
As for the third layer, according to Zhang, it is a liquid outer core of iron and nickel that generates the magnetic field of the planet, and it is above the fourth layer, which is a solid inner core.
Two Australian scientists analyzed the intersection of seismic waves from large earthquakes, and found that in the center of the Earth is a completely different layer.
"We have now confirmed the existence of the deeper inner core," said Hrvoj Tcalcic, professor of geophysics at the Australian National University in Canberra, one of the two scientists.
Tcalcic and researcher Tan Son Pham estimate that the innermost inner core is about 800 miles across, with the entire inner core about 1,500 miles across.
Their findings were published last Tuesday in the journal Nature Communications.
Harvard seismologists Miyake Ishii and Adam Dezyonski first proposed the idea of a deeper inner core in 2002 based on the characteristic properties of the velocity of seismic waves passing through the inner core.
Scientists already knew that the speed of seismic waves traveling through this part of the Earth varies with direction. Waves moved faster when traveling from one pole to the other along the Earth's axis and slower when traveling perpendicular to the axis.
Geophysicists believe that the difference in velocities, a few percent faster along the polar tracks, arises from the alignment of iron crystals in the inner core.
But in a small area in the center, the slowest waves were those moving at an angle of 45 degrees to the axis instead of 90 degrees, Harvard seismologists said.
The new research, according to Zhang, takes advantage of the fact that seismic waves also bounce back. Thus a seismometer close to the epicenter could detect the reflection of the wave, which traveled through the Earth and bounced back, passing the innermost core twice. These waves can also be reflected back and forth again, traveling through the innermost core four times.
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