Earth’s inner core is changing it’s shape !

Recently, scientists have discovered that the shape of inner core of Earth has been changing over the past two decades. Earlier researchers have confirmed about slowing down of inner cores’s rotation and rotating in the opposite direction of the planet’s surface.

The inner core of earth occurs as solid state and mainly composed of iron (Fe) and nickel (Ni). The temperature of inner core is very high reaching 5400°C and the pressure is over 3 million times greater than what we experience on surface of earth. Earlier scientists have suspected about deformation of the core and now they have found evidence using seismic activity generated by earthquake.

Scientists have observed variations in seismic waves passing through Earth’s inner core, suggesting changes in its rotation or shape over time. The recent research confirmed that the inner core’s rotation has fluctuated—first spinning faster, then slowing down relative to the rest of the planet. By analyzing seismic waves from 121 repeating earthquakes recorded between 1991 and 2023, researchers found evidence of both rotational and non-rotational changes. Differences in seismic data from two monitoring stations in North America between 2004 and 2008 suggest that these changes likely originate in the shallow inner core. The changes near the inner-core boundary most likely result from viscous deformation driven by coupling between boundary topography and mantle density anomalies or traction on the inner core from outer-core convection.

Dr Vidale from Department of Earth Sciences, University of Southern California described the potential cause of the deformation and said, “Maybe the topography is going up and down. Maybe it’s sloughing around like landslides. The most likely thing is the outer core is just pushing on the inner core and moving it around a little bit.”

The consequence of this process may affect the magnetic field of Earth as highlighted by researchers. Earth’s magnetic field is generated by the interaction between solid inner core and molten outer core. Since the inner core continues to grow the outer core gradually shrinks and could result a solid core leading to collapse of Earth’s magnetic field in billion years.

Reference: Vidale, J.E., Wang, W., Wang, R. et al. Annual-scale variability in both the rotation rate and near surface of Earth’s inner core. Nat. Geosci. (2025). https://doi.org/10.1038/s41561-025-01642-2