Forces deep underground seem to be deforming Earth’s inner core

The solid nucleus inside the earth seems to have changed in the form of the last 20 years.

Since the 1990s, models and seismic measurements stated that the nucleus of the earth’s iron-nickel moves at its rhythm. Over the decades, the rotation speed of the internal core increases and slows down compared to the rest of the planet, such as Length of day.

These rotation changes are mainly due to the magnetic forces produced in the outer liquid nucleus outside the Earth John Vidale At Southern California University. “This flow is constantly drawn by the inside nucleus.”

These magnetic forces or related processes can change the shape of the inside nucleus, as well as rotation. In fact, some measurements of seismic waves that pass through the center of the planet seemed to indicate that. Uncertainty about the basic rotation made it impossible to distinguish a change of rotation and change.

Now, Vidale and his colleagues have studied seismic waves caused by 128 earthquakes from the coast of South America between 1991 and 2023. The waves measured the instruments of Alaska after passing the planet.

Of these, researchers identified 168 pairs of seismic waves that passed the same area or close to the internal nucleus, but for years apart. It is possible to identify these matches Recent works To better limit changes in the inner core rotation, says Vidale.

In each pair of internal core they shared a similar model, suggesting that it was not changed in these areas of the first and second earthquake in these areas of our planet. The waves of interior were crossed in pairs that they did not match, if changing something around the nucleus, the differences in the rotation could be explained.

The researchers say the inside nucleus is not only his rotation over his decades, but also changes its rotation, but also changes form. These changes probably would cause convections magnetically pulling magnetically in the external core, through the interior solid corners and interior core interactions. Lower Mantle structuresThe core of our planet and the layer between the crust.

Hrvoje tkalčić In the national university was not involved in research, they say “forward”, to resolve rotation changes in the inner core. However, a change in shape is not the only explanation of unbalanced seismic waves.

As Vidale and his colleagues recognize, these differences could also be affected by changes in the external core, within the internal base core or even melted materials from the melted materials from the inside nucleus. “It’s very difficult to tell,” says Vidale. It suggests researching more repeated earthquakes in the future, it will help identify changes in more details.

Tkalčić said more seismological measurement in remote places, like the floor of the ocean, would help. “This is important to understand the evolution of the deepest interior of the earth until the formation of the planet to the present day,” he noted.