“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," Song said in the statement.
What did the researchers find? The seismic wave data suggests that iron crystals in the innermost regions of the inner core point east-west, whereas iron crystals in the inner core's outer regions point north-south. The researchers deduced that there must be a distinct inner-inner core that takes up about half the diameter of the whole 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," Dr. Simon Redfern, a professor of Earth Sciences at the University of Cambridge in England, who was not involved in this research, told BBC News. "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."
The study was published online in the journal Nature Geoscience on Feb. 9.
What else is inside Earth? Take a subterranean tour in the "Talk Nerdy To Me" video below.