Multiple Blue Rings

According to a new study, Earth's inner core may have stopped rotating and could even go into reverse.

The Earth is made up of crust, mantle, and inner and outer cores.  Earth's innermost layer is the core, which is separated into a liquid outer core and a solid inner core. 

Earth's core is about the size of Mars, with a radius of nearly 2,200 miles. It contains about one-third of Earth’s mass and consists mostly of iron and nickel.

The outer core is 2,300 kilometers (1,429 miles) thick, while the inner core is 1,200 kilometers (746 miles) thick. 

The outer core is mainly composed of a nickel-iron alloy (liquid iron), while the inner core is almost entirely composed of a pure solid iron body.

The solid inner core is located about 3,200 miles below Earth's crust. The liquid outer core separates the solid inner core from the semi-solid mantle, allowing the inner core to rotate at a different speed from Earth's rotation.

Yi Yang and Xiaodong Song studied the seismic waves from earthquakes that have passed through the Earth’s inner core along similar paths since the 1960s to infer how fast the inner core is spinning.

Their findings were published on Monday in the journal Nature Geoscience. According to them, the outcome of this research study was unexpected. 

Seismic records, which previously changed over time, have shown little variation since 2009. According to them, this indicated that the inner core rotation had paused.

They stated in the study that "we show surprising observations that indicate the inner core has nearly ceased its rotation in the recent decade and may be experiencing a turning-back."

"You can clearly see change when you look at the decade between 1980 and 1990, but there isn't much change when you look at 2010 to 2020," added Song. 

The magnetic field generated in the outer core drives the spin of the inner core, which is balanced by the gravitational effects of the mantle. 

Understanding how the inner core rotates may give insight on how these layers interact and other processes deep within the Earth.

However, the speed of this rotation, and whether it varies, is debatable, according to Hrvoje Tkalcic, a geophysicist at Australian National University who was not involved in the study. The inner core, he said, "doesn't come to a full stop."

According to him, the study's findings "mean that the inner core is now more in sync with the rest of the planet than it was a decade ago when it was spinning a bit faster." "There is nothing cataclysmic going on," he added.

But according to Song and Yang's calculations, a small imbalance in electromagnetic and gravitational forces could slow or even reverse the rotation of the inner core.

They believe this is part of a seven-decade cycle, with the previous turning point, and that the turning point prior to the one they detected in their data around 2009/2010 occurred in the early 1970s.

Tkalcic, said the study’s “data analysis is sound.” However, the study’s results “should be taken cautiously” as “more data and innovative methods are needed to shed light on this interesting problem.”

Read Prinsli World All Stories