According to earthquake evidence, the rotating solid inner core of the Earth may slow down a bit.
Researchers Yang Yi and Song Xiaodong from Peking University in China studied measurements of seismic waves passing through the Earth from nearly identical earthquakes that occurred in the 1960s.
These waves must be in some respects the same wherever they occur, if the earth had a constant structure throughout. However, differences in the nature of the waves and the time of passage give an idea of the discussed processes and actions occurring deep inside the Earth over decades.
Related: How did Earth’s core stay as hot as the Sun’s surface for billions of years?
Study published (will open in a new tab)found in the journal Nature Geoscience that the planet’s solid iron core, 3,200 miles (5,150 kilometers) below our feet, was spinning slightly faster than Earth’s mantle. But since 2009, the time difference between waves passing through the Earth is negligible, suggesting that the rotation has slowed down and could soon, if we could peer into the core, spin in the opposite direction relative to us (rather than actually reverse direction). Previous studies have assumed a stable rotation of the inner core.
However, this is not an event that stops the Earth. For example, this will not seriously affect the Earth’s magnetic field, which is created by the movements of the molten outer core.
There is also evidence that this apparent deceleration, acceleration, and rotational fluctuation of the inner core is part of a cycle lasting about 70 years, likely due to the gravitational connection between the Earth’s inner core and the much more massive mantle.
The authors conclude that fluctuations in the rotation of the inner core coincide with changes in the Earth’s surface system, such as tiny fluctuations in the length of the day and the magnetic field. “Thus, our discovery may imply a dynamic interaction between the deepest and most superficial layers of the Earth’s solid system,” the authors write.
However, there is some controversy over what the data is, and despite headlines stating that the Earth’s inner core may change direction, some Earth scientists and science communicators are calling for a smarter approach. (will open in a new tab) on learning.
“The inner core doesn’t stop completely,” Hrvoe Tkalcic, a geophysicist at the Australian National University, told CNN.com. (will open in a new tab). Instead, according to Tkalcic, the discovery simply indicates that “the inner core is now more in sync with the rest of the planet than ten years ago, when it was spinning slightly faster.”
“Nothing catastrophic is happening,” he added.
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