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Study on Earth’s Inner Core Changes
Context:
A groundbreaking study has revealed that Earth’s inner core is undergoing structural changes, challenging the long-held belief that it remains stable over human timescales.
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The research, published in Nature Geoscience, suggests that interactions between the molten outer core and solid inner core may be responsible for these changes, potentially impacting the rotation of the inner core and even subtly altering the length of a day.
Cause of Change
- The outer core is made up of molten iron and nickel and is turbulent, which may be causing the inner core’s surface to undergo dynamic shifts. As the outer core churns, it likely stirs up the solid inner core at its boundary.
- This interaction may cause changes in topography of the inner core’s surface, though the exact extent and pattern of these changes are still uncertain.
How Scientists Detected These Changes?
- Researchers analysed seismic waves generated by earthquakes, which travel through Earth’s layers before being detected by seismometers.
- Comparing wave patterns over decades, they noticed anomalies indicating structural shifts in the inner core.
- The findings suggest the inner core is not as rigid as previously believed but is instead undergoing continuous transformation.
Key Findings
- The inner core, previously believed to rotate independently, now appears to be experiencing a slowdown in its spin.
- Seismic wave data from 121 repeating earthquakes (1991–2024) near Antarctica’s South Sandwich Islands provided evidence of unexpected physical processes within the core.
- Researchers found signs of structural changes near the inner core’s surface, suggesting it is more dynamic than previously thought.
- The likely cause is viscous deformation, a process where materials flow under stress—similar to how honey or magma moves.
Implications for Earth’s Magnetic Field
- The solidification of the inner core drives heat flow within the outer core, which is responsible for generating Earth’s magnetic field. Understanding the inner core’s behaviour could provide insights into the history and dynamics of the planet’s deepest layers.
- Geoscientists are still uncertain about how the inner core’s solidification affects the magnetic field and how it may have influenced the planet before solidification began.
