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USC scientists have recently published groundbreaking research in the journal Nature, providing compelling evidence that the Earth’s inner core is slowing down in relation to the planet’s surface. This discovery sheds light on a long-standing scientific debate about the movement of the inner core.
The Inner Core’s Mysterious Behaviour
For decades, researchers have grappled with understanding the dynamics of the Earth’s inner core. Some studies suggested that it rotated faster than the Earth’s surface, while others proposed different models. Now, USC’s latest study settles the matter: the inner core has indeed decreased its speed since around 2010, moving more slowly than the Earth’s surface.
Seismic Clues and Inescapable Conclusions
Lead researcher John Vidale, Dean’s Professor of Earth Sciences at the USC Dornsife College of Letters, Arts and Sciences, recalls his initial surprise when analysing seismograms that hinted at this change. However, further observations confirmed the pattern: the inner core had slowed down for the first time in many decades. The USC study provides the most convincing resolution to this longstanding debate.
Backtracking and Relative Speed
The inner core’s behaviour is intriguing. It now appears to be backtracking relative to the planet’s surface, moving slightly slower than the Earth’s mantle. This reversal in speed marks a significant shift from its behavior in previous decades. Imagine a solid iron-nickel sphere, roughly the size of the moon, sitting over 3,000 miles beneath our feet. This enigmatic inner core cannot be directly observed; instead, scientists rely on seismic waves from earthquakes to create renderings of its movement.
Unconventional Approaches
Vidale and Wei Wang of the Chinese Academy of Sciences took an innovative approach. Instead of relying solely on traditional methods, they analysed waveforms and studied repeating earthquakes. Repeating earthquakes occur at the same location, producing identical seismograms. By compiling and analysing seismic data from the South Sandwich Islands and utilising information from past nuclear tests, the researchers pieced together a comprehensive picture of the inner core’s behavior.
Implications for Earth’s Surface
The slowing down of the inner core has implications for our planet’s surface. While the exact effects remain speculative, changes in the inner core’s movement could alter the length of a day by fractions of a second. Gravitational tugs from the dense regions of the rocky mantle and the churning of the liquid iron outer core likely contribute to this phenomenon.
In summary, USC’s study provides a crucial piece of the Earth’s puzzle, revealing the inner core’s surprising behavior. As we continue to explore the mysteries of our planet’s deep interior, this discovery opens new avenues for understanding Earth’s dynamic processes.
