Earth's inner core slows down: New research unveils 70-year cycle
Earth's inner core, a solid metal ball spinning independently within the planet, has significantly slowed down. Published in the journal Nature, these findings reveal a 70-year cycle in the core's rotational speed, providing critical insights into the complex dynamics of Earth's interior.
Challenges of Studying the Inner Core
Studying Earth's deep interior directly is impossible. Seismologists gather information by examining the behavior of seismic waves from large earthquakes that reach the inner core. Differences in these waves, observed at different times, allow scientists to measure changes in the core's position and calculate its spin.
«Differential rotation of the inner core was proposed as a phenomenon in the 1970s and '80s,» said Dr. Lauren Waszek, a senior lecturer at James Cook University. Seismological evidence published in the 1990s confirmed this rotation. However, subsequent studies have disagreed on the rate and direction of the core's rotation relative to the mantle. Some analyses even suggested the core didn't rotate at all.
Recent Findings
A model proposed in 2023 suggested that the inner core had previously spun faster than Earth but had slowed down significantly. A new study supports this hypothesis, confirming that the core's deceleration is part of a decades-long pattern of speed changes. The research also indicates that changes in rotational speed follow a 70-year cycle.
Cycle of Changes
The new findings indicate that changes in rotational speed follow a 70-year cycle, said study co-author
