SCITECH | Study confirms Earth inner core slowing down a part of 70-year oscillation cycle

By Jay Adrian Lotivio

A study published in Nature last June that analyzed 121 earthquake events from 1991 to 2023 confirmed an approximate seven-decade oscillation cycle of the Earth’s Inner Core (IC) where it varies from superrotation, where it rotates faster relative to the rest of the planet, to slowing down so much it has moved backward relative to the layers around it.

The cycle follows a superrotation period during the 1970s, slowing down around 2008 up to the same speed as the other layers, then moving slower and slower. The study predicts that the core will start moving faster again in five to 10 years.

The projected effects of this change have not been entirely proven true. According to a 2023 study, its effects could be related to the magnetic field or shortening our days; the study instead is sure that it shines a light on how processes we could not see with our own eyes continue to work beneath our feet.

The rotation of the inner core is facilitated by the same phenomena that powers the Earth’s magnetic field, and gravitational and electromagnetic interactions between it, the fluid outer core, and the mantle can affect the IC’s rotation, either slowing it down or speeding it up. This was found due to changes in the behavior of earthquake waves as it travels through the Earth, manifesting in slight changes in wavelengths and time it reaches areas, called temporal changes.

The study also mentions that evidence points to a notion that the inner core deforms and reforms, as variations between acceleration rates of the core were also reported.

The Earth’s inner core was first discovered by Danish seismologist Inge Lehmann in 1936, and has been inferred to be solid due to its interactions with waves travelling through the Earth.

Read the study here: https://www.nature.com/articles/s41586-024-07536-4