Scientists from University of Southern California (USC) have come to know by finding evidence that the Earth’s inner core oscillates. This evidence contradicts the previously accepted models suggesting that the inner core of the Earth consistently rotated with faster rate than Earth’s surface.
Their study, which has been published on 10 June 2022 in the journal Science Advances, shows that during the 6-year period from 1969-1974, the inner core of the Earth changed its direction.
According to the scientists, their model of inner core movement also explains the change in the length of a day, which has been shown to oscillate persistently for the last several decades.
John E. Vidale is coauthor of the study and Dean’s professor of Earth Sciences at USC Dornsife College of Letters, Arts and Science.
He said that from their findings, they could see the Earth’s surface shifts compared to its inner 6 as people had asserted for twenty years.
He added that their recent observations showed that the inner core had spun a little slower from 1969 to 1971 and then changed direction from 1971 to 1974. He further said that they also noted that the duration of the day had grown and shrunk.
We can conclude from those two coincidences that the inner core of the earth oscillates.
The inner core, which is a dense and hot ball of solid iron as large as Pluto, has been shown to move and alter over decades.
Researchers struggle through indirect means to observe the behavior of the core, because directly it is impossible to note the speed, change and cause of the change in motion.
The first research to suggest that the inner core rotates at a faster was published in 1996. It stated that the inner core rotated with higher speed as compared to the rest of the planet. This rotation is also called super rotation. The inner core rotates roughly at 1 degree per year, according to the research. Subsequently, findings from Vidale strengthened the idea of super rotation.
Wei Wang and Vidale discovered by measuring the compressional waves that resulted from the nuclear explosions that the inner core had reversed its direction, subrotating at least a tenth of a degree per year.
The study shows that the inner core oscillates based on change in the duration of the day, plus kr minus 0.2 sec over 6 years.