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Researchers report that they're obsessed with seismic waves across the Earth's inner core, allowing them to figure out what it's like: Solid, but softer than previously thought.
Scientists predicted the Earth has a solid inner core and liquid outer core 80 years ago, based on inconsistent measurements with just one single core. The solid core should accompany a special kind of seismic wave, called J waves, but it's been difficult to detect the waves – until now.
"Detection of J waves confirms that Earth's inner core is solid, but elastically less stiff than the previous estimate," the authors, from the Australian National University, wrote in their paper published in Science.
We have long inferred based on observations that the Earth has layers: A crust; a thick, hot mantle; a liquid outer core; and a solid inner core.
These inferences are based on seismic measurements. Seismic waves are just vibrations, which could be caused by volcanoes and earthquakes or even human-caused explosions. Earth's insides must look like.
But it was a long time ago that they would have a very small amplitude – they'd be really weak.
Rather than spotting the waves directly, Hrvoje Tkalčić and Thanh-Son Pham looked at global seismogram data and correlated the results, meaning they looked at the differences in the readings. Among them, they were able to pick out specific signals representing the waves traveling through the inner core.
This study has been made to be effective, but it has been suggested that the subject of this study should be considered This means the core may also be softer than previously thought.
The researchers explain that there is more work to be done, such seismograms and placing seismic measuring equipment in new places.
And while there are still questions about the nature of Earth's inner core, it's an important result, Jessica Irving, Assistant Professor in Geoscience at Princeton, wrote in a Science commentary. "The observation of the Earth's 'soft heart'."
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