Excerpt from cnet.com

Though the seismic waves from earthquakes are best known for their abilities, in the hands of geologists, they can be powerful tools of discovery. A team at the University of (UI) has just used the rumbles from quakes to more closely examine the core of our , and what they found there was quite a surprise. It seems our Earth’s core has another core that measures about the diameter of the original core.

What demarcates this “inner-inner core” is that the iron crystals it contains are oriented on an east-west axis, unlike the iron crystals in the “outer-inner core” which organize along a north-south axis.

“The that we have two regions that are distinctly different may tell us something about how the inner core has been evolving,” said Xiaodong Song, a professor of at UI who, along with postdoctoral researcher Wang, led the team responsible for the discovery. “For example, over the of the Earth, the inner core might have had a very dramatic change in its deformation regime. It might hold the to how the planet has evolved. We are right in the center — literally, the center of the Earth.”

The researchers’ findings were published in the journal Nature yesterday.