Stains in the Earth's core could cause "geomagnetic jolts" in the magnetic field

Every few years, observatories of magnetic fields record rapid changes in the position or strength of the planet's magnetic field, called geomagnetic shocks. The cause of these changes has remained a mystery.

Improvements to ground-based observatories and the increased number of satellite-based magnetic field measurements have allowed scientists to better understand the magnetic behavior of the planet. Although we can not look directly into the Earth's core, these measurements have allowed scientists to build models to help infer what might happen there. More recently, scientists have realized that moving spots within the nucleus could explain geomagnetic shaking.

"The ability to numerically reproduce saccades offers a new way to probe the physical properties of the deep interior of the Earth," write researchers Julien Aubert from the University of Paris and Christopher Finlay from the Technical University of Denmark in Nature Geoscience.

Earth scientists are virtually certain that the planet generates its own magnetic field through geodynamo: a conductive liquid metal motion generated by heat inside the nucleus, associated with the spin of the planet. The changes are usually slow – as in a new and fanciful train, where you hardly perceive the forces of acceleration or slowing down. But sometimes, the magnetic field undergoes "jolts", where it goes unpredictably from acceleration to deceleration, similar to the jolts inducing a lash that you might feel in an old train in ruins.

Simulation of the material passing through the nucleus, potentially causing geomagnetic shocks. (Video: Aubert and Finlay, Nature Geoscience (2018))

According to the observed data, these "shakes" occur in just a few years and appeared in 2007, 2011 and 2014. To better understand this, the researchers constructed a simulation of the Earth, in which the outer core is represented by a spherical shell Rotary filled with an electrically conductive liquid, and the inner core and the coat in the form of solids then taking the liquid sandwiched. It's like a rotating jaw with a felt layer between the center and the outer shell.

The model revealed that isolated spots in the liquid could move up and around the nucleus, creating waves through the electrically charged atoms of the liquid. Once these waves are stopped by the solid mantle, they compress, causing temporary disturbances of the magnetic field that cause the geomagnetic shock. It would take about 25 years between the publication of gout and the observation of a reflex.

It's a model based on what we know from the inside of the Earth, and it's worth taking (and all models) with a grain of salt. This is also not the only possible explanation for these jerks – others have suggested that they came from a twisting or twisting oscillation in the nucleus, although the researchers behind the new paper argue that the torsional oscillations are too weak to generate the signals observed in real life.

Nevertheless, the models are essential to better understand how deep movements are moving on our planet, and the understanding of jolts could help scientists predict them in the future. You may know that the magnetic field protects us from the sun's rays that would make the planet unlivable. So it's good to be able to understand it better.