Simon Redfern tackles new ideas about the earth’s core puzzle in BBC News:
Seismic data indicate that the western and eastern hemispheres of Earth’s inner core differ, and this has led some to suggest that the core was once subjected t an impulse – presumably from the collision of a space rock or planetoid which shook the whole Earth. The core, it is suggested, is constantly moving sideways. As it does, the front side is melting and the rear side crystallising, but the core is held centrally by gravity. With all these seismic complexities, the link between the crystal structure and the geophysical observations has yet to be resolved. In Scientific Reports, Maurizio Mattesini from the Complutense University of Madrid, Spain, and colleagues propose a novel possibility for the structure of the core: that it is composed of mixtures of different iron arrangements distinguished by the way their atoms pack together. By comparing seismic data from over one thousand earthquakes across the globe with quantum mechanical models for the properties of iron, they suggest that seismic variations directly reflect variations in the iron structure. They propose that the eastern and western sides of the core differ in the extent of mixing of these distinct structures, and suggest their results account for the dynamic eastward drift of the core through time.
You can find the entire article here.