Earth’s core has a new layer
Big news in the world of geophysics today. Researchers from University of Illinois have confirmed the existence of an “inner, inner core” of the Earth.
Previous studies suggested a more simple model of our core, proposing that the Earth has an inner core of solid iron and an outer core of liquid and other heavy elements. Seismic data was gathered from around the world and 3D models were created from the data, showing an obvious boundary between the inner core and the newly discovered, smaller core.
In their analysis, Sun and Song used a three-dimensional tomography technique to invert the anisotropy of the inner core. They parameterized the anisotropy of the inner core in both radial and longitudinal directions. The researchers then used a three-dimensional ray tracing method to trace and retrace the seismic waves through the inner core iteratively.
What they found was a distinct change in the inner core anisotropy, clearly marking the presence of an inner inner core with a diameter of about 1,180 kilometers, slightly less than half the diameter of the inner core.
The layering of the core is interpreted as different texturing, or crystalline phase, of iron in the inner core, the researchers say.
“Our results suggest the outer inner core is composed of iron crystals of a single phase with different degrees of preferred alignment along Earth’s spin axis,†Sun said. “The inner inner core may be composed of a different phase of crystalline iron or have a different pattern of alignment.â€
Fraser Cain at Universe Today has more information as well.
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