Earth's Inner Core Slowing Down and Reversal

INNER CORE SLOWING DOWN SINCE 2009 AND REVERSE AFTER 2023 STUDY

The inner core of the Earth's movements are slowing down and also is moving in reverse direction or backwards according to confirmation done by scientists.

Scientists have been observing the core since 1936, it is not easy to observe the Earth's inner core. Danish seismologist Inge Lehmann made this inner core discovery.

There is increasing evidence suggesting that the inner core's spin is changing dramatically in recent times and scientists have solved this mystery as to why this is happening and what it means.

Scientists have used the method of the earthquake to identify the inner core moments, the P and S waves emerge during the earthquake and observing and studying it helps the scientist these seismic waves explain the inner Earth situation. The data of the seismic moment was first published in 1990, according to recent studies and reports of 2023 the core that used to spin faster than the Earth itself is now spinning slower.

The Nature Journal article published on  12 June 2024, explains the backward moments of the inner core in detail. The cause of these movements is that the solid contains iron and nickel whereas the outer core is liquid. The Earth’s magnetic field influences the movement of the inner core, particularly in the active region where the inner and outer cores meet.

Studying the rotation of the inner core is crucial for a deeper understanding of our planet. It allows scientists to develop comprehensive dynamic models of the Earth's systems. Additionally, examining seismic waves can improve our understanding and management of earthquakes. 

Earth's core

Earth's core is the hottest part of the planet, equivalent to that of the Sun's surface. The core is buried around 5,180 kilometres deep inside the Earth and consists mainly of iron and nickel. The inner core is surrounded by a liquid metal outer core, which acts as a barrier with the rest of the Earth. This barrier allows Earth's core, akin to a hot solid ball of metal, to spin independently and not necessarily align with the rest of the planet

Is the rotation speed of Earth's core slowing down?

Danish seismologist Inge Lehmann discovered the planet's inner core in 1936. Since then, scientists have continued to debate its rotation speed and direction. One reason scientists have limited evidence to prove their point is that it is impossible to observe or collect direct samples of Earth's deep interior. Most of the research and studies are based on variations between waves of similar strengths passed through the core at different times.

Data from seismograms from repeated earthquakes and explosions on Earth indicate that the rotation speed of the solid inner core has been constantly degrading compared to the Earth's surface over the past few years, according to a new finding published in the journal Nature in June this year.

The new findings also confirm that the changes in rotational speed follow a 70-year cycle.

The implications of the inner core's slowdown for our planet remain an open question, with some experts suggesting that Earth's magnetic field could be affected.

CAUSE OF SLOWING OF INNER CORE: 

Buried about 3,220 miles (5,180 kilometres) deep inside Earth, the solid metal inner core is surrounded by a liquid metal outer core. Composed mostly of iron and nickel, the inner core is estimated to be as hot as the surface of the sun - about 9,800 degrees Fahrenheit (5,400 degrees Celsius).

Earth's magnetic field pulls on this solid ball of hot metal, causing it to spin. Meanwhile, the gravity and flow of the fluid outer core and mantle exert a drag on the core. Over many decades, the push and pull of these forces have resulted in variations in the core's rotational speed, according to Vidale.

The movement of metal-rich fluid in the outer core generates electrical currents that power Earth's magnetic field, which protects our planet from harmful solar radiation. Although the inner core's direct influence on the magnetic field is not fully understood, scientists reported in 2023 that a slower-spinning core could potentially impact it and also slightly shorten the length of a day.

Dr Vidale and his coauthors observed seismic waves produced by earthquakes in the same locations at different times for this study. They found 121 examples of such earthquakes occurring between 1991 and 2023 in the South Sandwich Islands, an archipelago of volcanic islands in the Atlantic Ocean to the east of South America's southernmost tip. The researchers also looked at core-penetrating shock waves from Soviet nuclear tests conducted between 1971 and 1974. 

IMPLICATION OF SLOWING INNER CORE : 

1.  The researchers highlighted that when the core spins slowly, the mantle speeds up. This shift makes Earth move faster, and the length of a day shortens. 

2. The scientists feel that one possibility could be metal inner core is not as solid as expected. 

3. Although the inner core's direct influence on the magnetic field is not fully understood, scientists reported in 2023 that a slower-spinning core could potentially impact it and also slightly shorten the length of a day.