As curious as scientists are about space and its surprising discoveries, they are also constantly attempting to know more about Earth’s inner core. While previous studies have revealed that the centre of Earth is a solid metal ball, a kind of “planet within a planet,” the formation of the core remains a mystery. Now, a new study reveals that the inner core might not be a homogenous mass, as once assumed by scientists.
In a new study, researchers from the University of Utah used seismic waves from naturally occurring earthquakes to probe into Earth’s inner core. The findings revealed that the Earth’s core is like a pattern of different “fabrics,” according to a press statement by the University of Utah. The study was published in the journal Nature. “For the first time, we confirmed that this kind of inhomogeneity is everywhere inside the inner core,” Guanning Pang, lead author, said in the statement.
For this research, the scientists used a special dataset generated by a global network of seismic arrays to detect nuclear blasts. Pang analysed seismic waves from more than 2,450 earthquakes, with a magnitude exceeding 5.7. The way these waves bounced off the inner core helped the researchers understand the planet's internal structure.
Seismic waves were first used to determine that the inner core was solid in 1936. The new study reveals that inhomogeneity tends to be stronger as one gets deeper. Toward the centre of the Earth, it tends to be stronger. “We think that this fabric is related to how fast the inner core was growing. A long time ago, the inner core grew really fast. It reached an equilibrium, and then it started to grow much more slowly,” seismologist Keith Koper, who oversaw the study, said in the statement. As not all iron became solid, some liquid iron might be trapped inside, he added.
Earlier this year, scientists had also discovered a new layer in Earth’s core, the innermost inner layer. In a study published in Nature Communications, the researchers confirmed that the fifth layer is made of iron and nickel, the same materials that make up the rest of the inner core.