Scientists at the Australian National University have confirmed that the Earth's inner core is in fact double, with an unknown layer present. The study, published in the Journal of Geophysical Research, is reported in a press release at Phys.org.
Researchers have compared many models of the Earth's inner core with data on the travel time of seismic waves through the interior of the planet, collected by the International Seismological Center. It turned out that the observed pattern corresponds to several of the most probable variants of anisotropy of the core, that is, it has a certain internal structure that affects the speed of seismic waves.
Some experts believe that the material of the inner core causes the waves to travel faster parallel to the equator, but others argue that higher speeds are characteristic of waves traveling parallel to the Earth's axis of rotation. In the new scientific work, the second version was confirmed.
This indicates that the early Earth underwent two separate cooling phases, and the iron crystals that make up the inner core are stacked differently to form a more complex structure.
