The Earth’s inner core, located about 5,180 kilometers deep, is a solid sphere composed mainly of iron and nickel, with temperatures estimated at around 5,400 °C. Since its discovery by the Danish seismologist Inge Lehmann in 1936 this nucleus was at the center of intense scientific studies and debates, especially regarding its rotation.
A recent study published in Nature geoscience suggests that the rotation of the inner core is not constant. Titled “Multidecadal variation in the rotation of the Earth’s inner core” (Multidecadal variation of the rotation of the Earth’s inner core), the study indicates that in the 1970s the inner core rotated slightly faster than the Earth’s surface. However, around 2008, this rotation began to slow down, and between 2008 and In 2023, the core appeared to move in the opposite direction to the Earth’s mantle. These oscillations follow a cycle of about 70 years, according to the authors’ conclusions.
Potential impacts on Earth
These changes in the rotation of the inner core can influence the Earth’s magnetic field, generated by the movement of molten iron in the outer core. Changes in the rotation of the inner core can affect the dynamics of the magnetic field, although the exact impact is still being studied. Furthermore, these changes can influence the length of the days, but these variations are minimal and practically imperceptible in everyday life.
To study these changes, scientists analyze seismic waves generated by earthquakes passing through the inner core. By comparing data from seismic events that occurred in different periods, it is possible to deduce variations in the rotation of the core. For example, in the study published in Nature geoscienceresearchers analyzed 121 earthquakes that occurred between 1991 and 2023 in the South Sandwich Islands, revealing changes in the core’s rotation pattern over time.
Source: Terra
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