A team of Chinese and U.S. scientists reported that may have found an inner core within Earth’s core by analyzing the clues left by earthquakes’ seismic waves. According to the researchers, the newly found core is smaller than the Moon and shows some interesting features.
Scientists currently hope that the discovery would help them learn more about early planet formation, its geological history, as well as about its deep inner processes.
The new-found core challenges previous theories about how Earth’s center may look like. Researchers explained that the Earth’s core, which is located nearly 3,100 miles beneath its surface, is not just a massive ball of iron as it was simplistically depicted for decades.
According to the findings, the core within the core is half the size of its host core and it also contains iron crystals. However, those crystals have a different orientation from the iron crystals within the outer core. The inner-inner core crystals align east to west, while the outer inner core’s crystals align north to south.
Scientists were puzzled by this finding, too. They believe that something “very substantial” must have happened to flip the orientation of the core. So, they plan to conduct a follow-up study to solve the mystery.
Still, the scientists do not have direct evidence of the inner-inner core’s existence. They only speculated its existence after studying the seismic data related to earthquake waves traveling through the planet’s inner layers.
“The waves are bouncing back and forth from one side of the Earth to the other side of the Earth,”
explained Xiadong Song, co-author of the findings and a geology researcher at the University of Illinois.
But Mr. Song and his colleagues used a different technique to map the planet’s inner core – they studied the ghost seismic waves ringing through the planet after the earthquakes had passed.
“The earthquake is like a hammer striking a bell; much like a listener hears the clear tone that resonates after the bell strike, seismic sensors collect a coherent signal in the earthquake’s coda,”
Prof. Song added.
Scientists noticed that the reverberations of earthquakes were enhanced more clearly by computer technology than the quake’s initial ring. Those reverberations helped the team develop a more accurate map of the Earth’s inner core and discover the core within the core. They said that mapping its actual structure was like reading the rings of a tree.
A study about the new findings was published Monday in the journal Nature Geoscience.
Image Source: Washington Post
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