Researchers Say Earth's Core Is Soft

When I grew up, I was told that our planet's core was made of lava – and that I'd never be able to dig through the planet to get out the other side. I was misinformed. While it still seems that I cannot tunnel through the planet (with the tools I have in my garage), the inner core of our planet Earth is apparently solid. Researchers Associate Professor Hrvoje Tkalčić and PhD Scholar Than-Son Phạm of The Australian National University (ANU) published a paper on the subject this week.

It's been a while since I went back to the latest in scientific understanding of the state of our Earth's core. As such, I wasn't aware of the following, per the research paper we're speaking about today: "Earth's inner core is thought to be solid, which means it should support shear waves." Shear waves are one of two main types of elastic body waves, or a transfer of energy that, in this case, moves through solid matter.

According to this new research, Tkalčić and Phạm were able to "correlate different types of seismic phases to finally determine the speed of shear waves in Earth's inner core." It was apparently difficult to detect shear waves through the inner core of our planet because our planet's inner core is so very small. But they did it!

According to Tkalčić and Phạm's findings, Earth's core is indeed solid, but not particularly hard. In fact the findings shown in this research were a full 2.5% lower than the "widely used Preliminary Earth Reference Model," so says the paper.

"The understanding of the Earth's inner core has direct consequences for the generation and maintenance of the geomagnetic field, and without that geomagnetic field there would be no life on the Earth's surface." said Dr Tkalčić according to Phys.org. "We don't know yet what the exact temperature of the inner core is, what the age of the inner core is, or how quickly it solidifies, but with these new advances in global seismology, we are slowly getting there."

For more information on this subject, see the publication Science where the paper "Shear properties of Earth's inner core constrained by a detection of J waves in global correlation wavefield" is published by Hrvoje Tkalčić and Thanh-Son Phạm. This paper was first published on the 19th of October, 2018, in Science volume 362, Issue 6412. This research can be found with code DOI: 10.1126/science.aau7649 as of this week.