Earth's inner core has an inner core of its own

[Dotini]

Thanks to a novel application of earthquake-reading technology, researchers have found that the Earth's inner core has an inner core of its own, which has surprising properties that could reveal information about our planet.

http://www.sciencedaily.com/releases/2015/02/150209113222.htm

The inner core, once thought to be a solid ball of iron, has some complex structural properties. The team found a distinct inner-inner core, about half the diameter of the whole inner core. The iron crystals in the outer layer of the inner core are aligned directionally, north-south. However, in the inner-inner core, the iron crystals point roughly east-west.

A research team from the University of Illinois and colleagues in China found Earth's inner core has an inner core of its own, with crystals aligned in a different direction.
Credit: Lachina Publishing Services

Journal Reference:

1. Xiaodong Song et al. Equatorial anisotropy in the inner part of Earth’s inner core from autocorrelation of earthquake coda. Nature Geoscience, Feb 9, 2015

 

[phinds]

Nature seems to always have surprises in store for us. Just when we think we've got something nailed down reasonably well, the nails pop loose ... keeps things interesting. Thanks for posting that.

 

[Dotini]

Here is a PhysOrg article with an amusing comments section on the discovery.
http://phys.org/news/2015-02-earth-geologists-mysteries-planet-core.html#ajTabs

 

[Bystander]

The iron crystals in the outer layer of the inner core are aligned directionally, north-south. However, in the inner-inner core, the iron crystals point roughly east-west.

What "in" Earth does this mean?

Edit: We're going to add not just one, but two anisotropic allotropes to the iron phase diagram?

 

[billiards]

Hmmm, an interesting use of the increasingly popular "seismic interferometry" technique..
The "inner inner core" is nothing new, it's been around for over 10 years now. So most of the media hype is just that, hype.
Previous work has suggested that this inner inner core can be explained away by heterogeneity in the outer inner core, and this work really doesn't seem to lay that concern to rest (to me at least). I suspect this paper is not the last word.

 

[Dotini]

A interesting and unique new image of our planet's mantle based on earthquake vibrations.

http://www.newscientist.com/article...-of-the-inside-of-the-earth.html#.VQgptkvoaX3

(Image: Ebru Bozdağ, University of Nice Sophia Antipolis, and David Pugmire, Oak Ridge National Laboratory)

Eavesdropping on earthquakes is painting a picture of the Earth's interior that looks like the swirling colours inside a marble. This view beneath the Pacific Ocean, based on simulations run by http://www.princeton.edu/geosciences/people/display_person.xml?netid=jtromp from Princeton University and his team, uses different colours to represent the speed of seismic tremors, giving an insight into the planet's inner structure.