USC scientists have made a revolutionary discovery on the nature of the enigmatic inner nucleus of the earth, revealing for the first time that this ball of iron and nickel 1,500 miles wide changed.
The interior nucleus of the planet was previously considered a hard and solid sphere. But a new study found that its edges are softer than made and change in shape when they press against liquid iron and nickel in the external nucleus of the earth.
“The molten external nucleus is widely known to be turbulent, but its turbulence has not been observed to disturb its neighbor the inner nucleus on a human time scale,” said USC Earth Sciences professor John Vidale, who led the study. “What we observe in this study for the first time is probably the disturbing external nucleus the inner nucleus.”
Vidal said that it is likely that the outer nucleus distorts the shape of the inner nucleus, pushing it to a kilometer or two in the areas where they rub. These results were published Monday in the journal Nature Geoscience. The study was conducted alongside researchers from the University of the Chinese Academy of Sciences, Cornell University and the University of Utah.
When the members of his team embarked on their research, they did not expect to document the structural changes in the inner nucleus of the earth. Instead, they focused on learning more on the slowdown in its rotation.
Previous research has revealed that the rotation of the internal nucleus slows down in relation to the rotation of the external crust, which can cause tiny changes in the rotation of the earth and subtly affect the duration of a day. Although these time changes are estimated only to a question of milliseconds per year, they accumulate on the eons.
Vidale said he was busy studying graphics that record the soil vibrations caused by seismic waves when a data set “curious to stand out from the others”.
“Later, I realized that I was looking at evidence that the inner nucleus is not solid,” he added.
His team studied seismic data of 121 repeated earthquakes in 42 locations near the Antarctic Sandwich Islands which occurred between 1991 and 2024.
Repeated earthquakes are earthquakes with the same magnitude and location. If a pair of repeated earthquakes occurs while the inner nucleus of the earth is in the same place in its rotation, scientists would assume that the recorded seismic data would be the same in the two earthquakes.
However, the curious data set that Vidale has encountered this logic, which prompted his team to realize that the differences they have observed were probably caused by changes in the shape of the inner nucleus.
“We see these subtle differences,” he said. “And if they are not (caused by) the inner turning point, the most likely possibility is that there is a certain deformation in the most soft outside nucleus.”
The scientific implications of this revelation are not yet clear, but vidal hopes that researchers can help to disentangle other mysteries linked to the inner nucleus and lead to a better understanding of the thermal and magnetic fields of the earth.
“We hope this has wider implications,” he said. “The reason we do is that we like to resolve the puzzles, and the foreigner and harder than we can solve, the more happy we are.”
