Researchers report that they have observed seismic waves crossing the inner core of the earth, so that they can figure…
Researchers report that they have observed seismic waves crossing the inner core of the earth, so that they can figure out how it is: firm, but softer than before.
Researchers predicted that the earth has a solid internal core and fluid outer core 80 years ago, based on measurements that do not match a single core. The fixed core should accompany a special kind of seismic wave, called J waves, but it has been difficult to actually detect the waves – so far.
“Detection of J waves confirms that the inner core of the earth is solid, although it is resiliently less rigid than previous estimation,” the authors of Australian National University wrote in his paper published in Science.
We have long derived based on observations that the Earth has stock: a crust; a thick warm coat a liquid outer core; and a solid inner core. These conclusions are based on seismic measurements. Seismic waves are just vibrations that travel through the earth, which can be caused by volcanoes and earthquakes or even human-induced explosions. Geophysics measure these waves to divert what the interior of the earth must look like. But it’s a long way between difficult to measure the waves produced in the solid inner core, because they would have a very small amplitude ̵
1; they were very weak.
Instead of detecting the waves directly, Hrvoje Tkalčić and Thanh-Son Pham looked at global seismogram data and correlated results, which means they looked at the differences in readings. Among all the different ways the waves could travel, the outer core and the inner core, they could choose specific signals representing the J waves traveling through the inner core.
This study could use these J waves to determine that the inner core is solid, but that the waves traveled more slowly through the current reference models suggest. This means that the core can also be softer than previously thought.
The researchers explain that further work is needed, such as taking more data from more seismograms and placing seismic measuring equipment in new places. And while there are still questions about the inner core of nature, it’s an important result, Jessica Irving, Deputy Professor of Geosciences in Princeton, wrote in a Science comment. “The observation of the J-phases will provide an additional tool for assessing the characteristics of the earth’s” soft heart “.”