The New Core Within Earth's Inner Core
The interior of the earth may have just gotten more interesting with the discovery of another distinct region hiding within the inner core. Say hello to our inner-inner core.
The core of the earth is as interesting as it is mysterious and inhospitable. The Mantle and Crust immediately below our feet are ok I suppose but a lot of the really cool stuff (and amazingly hot stuff as well) takes place far below that, within the various layers we call the core starting about 2,800 km below ground.
The outer core is, as you might imagine, under tremendous pressure with so much of the earth pressing down on it. You’d think this would make it a dense solid mass but that pressure also creates heat. That heat plus the tremendous heat released by radioactive decay allow the nickel and iron slush down there to stay in a viscous liquid state. This is a good thing because the eddy currents that are produced at that depth create the magnificent force-field around our planet called the magnetosphere that protects the earth from deadly radiation.
The inner core is an even more hellish place, as you might imagine. It’s so hot that it’s temperature, at 5,700C, rivals that of the Sun’s surface. Even these temperatures however, cannot turn the core to a liquid or gas due to the tremendous pressures exerted on it. This pressure had been estimated at 340 gigapascals which is almost 3.5 million more atmospheric pressures than you are experiencing right now (assuming you’re a human reading this on earth). The result is a mostly solid ball of an iron-nickel alloy that is 70% the diameter of the moon.
We will (probably) never be able to go down there ourselves, regardless what the movie The Core says (humans build a ship to travel to and fix earth’s core…lol). Drilling down that far as well seems so outlandish it’s just silly. We can however infer some of the key properties of the deep interior of the earth.
This is done using the powerful echoes created by earthquakes that reverberate within the earth and through the core. By analyzing this seismic wave data, it is possible to determine the characteristics of the material that the waves are traveling through by the impact of the former on the latter. A new analysis by an international team of geophysicists has revealed that the inner core appears to have a distinct area within its inner-most section. The so-called inner-inner core.
The nature of this difference has to do with the orientation of iron crystals. The outer-inner core has them oriented in a north-south direction. The inner-inner core however appears to have them pointing in an east-west direction. So if you were looking down on the earth from above the north pole, it would appear that the inner-core has been flipped onto its side compared to the outer-inner core. This difference appears to extend beyond just the position of the crystals however…their behavior is different as well. This could mean that the center-most part of the earth is made up of crystals in a different phase or it could be composed of an entirely different crystal altogether.
So what benefit could we derive from these discoveries assuming they are verified? Well, they could potentially help disentangle the long and complicated evolution of the earth and its interior.
“The fact we are discovering different structures at different regions of the inner core can tell us something about the very long history of the Earth.”
Since earth’s core drives plate tectonics as well as our magnetic field, its evolution was critical to the rise and maintenance of life as we know it on the earth. Perhaps we can use this research to anticipate its future evolution and any potential negative impact it could have on life.
I just hope we never need to watch “The Core” again to get ideas how to fix our core.
Image Credit: Lachina Publishing Service