Scientists at the University of Southern California have discovered the Earth's core is changing shape after analysing earthquake data.

A new, detailed probe of Earth's heart reveals that the rotating inner core doesn't just change in rotation speed – it also appears to change in shape, with subtle variations appearing in the way acoustic waves propagate through the planetary center.

Scientists of course cannot cut into Earth and directly observe its insides. Instead, their knowledge is inferred from the vibrations generated by earthquakes that pass through the planet. The speed and the direction of the seismic vibrations change depending on the density and the elasticity of the rocks.

Earth’s core is located below the middle layer called the mantle and the outer layer –or crust. It consists of two main parts–a liquid outer core and a more solid inner core. The outer layer is made of liquid iron-nickel and is responsible for producing Earth’s magnetic field.

Scientists found that the inner core’s structure changes as it rotates. It deforms at its border, potentially accumulating more material in some areas and less in others — almost like creating hills and valleys.

Seismic waves suggest the planet's solid inner core is being pulled out of shape – and it has undergone these changes over just a few decades

A new study has found evidence that the Earth's inner core may have changed shape. Far from taking place over geological timescales, the changes appear to have taken place within the last two decades.