‘Inner Inner Core’: center of the Earth has an inner core of its own
16 February 2015, Nirapad News : A distinct inner-inner core of the Earth must take up approximately half the diameter of the entire inner core. An international team of researchers has unlocked a deep secret of our planet. While the core at the center of the Earth was once thought to be a ball of solid iron, it turns out that this nucleus in fact contains its own hidden inner core. And this so-called “inner-inner core” seems to have some very peculiar properties.
“The fact that we have two regions that are distinctly different may tell us something about how the inner core has been evolving,” said Dr. Xiaodong Song, a professor of geology at the University of Illinois who co-authored a new paper documenting the discovery. “For example, over the history of the earth, the inner core might have had a very dramatic change in its deformation regime. It might hold the key to how the planet has evolved. We are right in the center — literally, the center of the Earth.”
For the study, researchers from Illinois and from China’s Nanjing University measured the travel patterns of seismic waves as they resonated and traveled through the ground during the aftermath of earthquakes which took place from 1992 to 2012. “The basic idea of the method has been around for a while, and people have used it for other kinds of studies near the surface. But we are looking all the way through the center of the earth,” said Song in a statement.
A closer analysis of seismic wave data led researchers to conclude that there are iron crystals present in the innermost regions of the Earth, known as the inner core, which point east-west, whereas iron crystals within the inner core’s outer regions direct a polarity of north-south. Therefore, a distinct inner-inner core of the Earth must take up approximately half the diameter of the entire inner core.
“People have noticed differences in the way seismic waves travel through the outer parts of the inner core and its innermost reaches before, but never before have they suggested that the alignment of crystalline iron that makes up this region is completely askew compared to the outermost parts,” said Dr. Simon Redfern, a professor of Earth Sciences at the University of Cambridge in England, who was not a participant in the study.
The conclusions could be significant to understanding the processes of how Earth was formed as well. “If this is true, it would imply that something very substantial happened to flip the orientation of the core to turn the alignment of crystals in the inner core north-south as is seen today in its outer parts,” added Redfern.