Two seismologists from the Australian National University have discovered another layer of our planet – the “innermost inner core”. They discovered new knowledge about the deepest parts of the Earth’s inner core thanks to seismic waves generated by more than two thousand earthquakes.
They describe the new layer as a solid “metal ball” with a diameter of about 640 kilometers, which is located in the center of the inner core. The results of the study were published in the journal Nature Communications. According to the authors, the investigation of the Earth’s interior is of fundamental importance for understanding the formation and development of planets.
A giant metal ball
Until now, geologists have divided our planet into four basic geospheres: the lithosphere, the mantle, the outer liquid core, and the inner solid core. New findings indicate that there is a fifth layer beneath them. “The existence of an inner metal ball inside the core, the innermost inner core, was assumed about twenty years ago. We now provide further evidence to support this hypothesis.” states the lead author of the study Thanh-Son Phạm.
Scientists used a new technique to amplification of signals that were recorded during various earthquakes by seismological instruments. Thanks to this, they were able to “see” the signals reflected multiple times from the core, and depending on how these waves were slowed down or accelerated by the material they traveled through, they obtained information about the properties of the material in different parts of the planet’s interior. “The results are exciting because they provide a new way to explore Earth’s inner core and its innermost region,” stated Pham.
Seismologists evaluated seismic waves, passing through the center of the Earth, which “float” on the opposite side of the globe than where the earthquake took place. These waves then travel back to the source of the earthquake. For example, this is how they studied an earthquake that originated in Alaska, the seismic waves reflected somewhere in the South Atlantic and then returned back to Alaska. “By stacking waves recorded by a growing number of global seismic stations, we observe up to five times the reverberations of waves from selected earthquakes.” it is stated in the article.
And who will it benefit?
The research results are important because if there really are two layers of the inner core, it suggests that they were created in two different time periods. “This inner core is like a time capsule of Earth’s evolutionary history—it’s a fossilized record that serves as a gateway to the events of our planet’s past. By events that took place on Earth hundreds of millions to billions of years ago,” Hrvoje Tkalčić said in a statement.
An interesting question now is how the two layers of the inner core actually formed. Scientists believe that some significant event may have occurred in the evolution of the planet, which caused fundamental changes in the structure of the core. “There are still many unanswered questions about Earth’s innermost core, which could hold secrets that will shed light on the mystery of our planet’s origin,” said Tkalčić.
Further research could shed light on how our planet evolved billions of years ago and how its magnetic field evolved over time, turning the inhospitable rock into a habitable home. Scientists are convinced that the study of the Earth’s core is not just an object of academic curiosity, but something that sheds light on the very development of life on the surface of our planet.
