Geophysics from the University of Leeds and the University of California in San Diego showed that the change in the direction of the magnetic field of the Earth can occur ten times faster than previously thought. Article with results of a study published in the journal Nature Communications.
Our magnetic field generate and maintain a convective flow of molten metal that forms the outer core of the Earth. The movement of liquid iron generates electric currents, which feed the magnetic field. It not only allows you to operate the navigation systems, but also protects people from harmful cosmic radiation and allows our atmosphere to evaporate into space.
The magnetic field is constantly changing. Today satellites can measure and monitor its performance, but much more important long-term changes in the magnetic field, which has been happening for thousands of years — long before humans invented the sensors to register. To understand the evolution of this protective “shell” researchers should analyze the magnetic field using various rocks, lava flows and other evidence. However, these methods do not allow to accurately estimate the rate of change of position of the magnetic poles, and other characteristics of the magnetic field of the planet.
The authors of the new study used a different approach. They combined computer modelling of the process of field generation with the reconstruction of changes in the magnetic field of the Earth over the last 100 thousand years. As a result, the researchers showed that in fact the field of our planet has changed over time to ten times faster than previously thought.
These rapid changes, according to the calculations of researchers, associated with a local weakening of the magnetic field. This means that these changes generally occurred at a time when the field changed polarity, or during geomagnetic variations, when the axis corresponding to the magnetic field lines moved away from the location of the North and South geographic poles.
The most striking example of this phenomenon — a sharp change in the direction of the geomagnetic field by about 2.5° per year 39 thousand years ago. This shift was associated with a locally weak field strength in the region off the West coast of Central America. Such events are revealed by computer simulation. It can be used to reveal much more detail of the physical properties of the magnetic field than traditional paleomagnetic reconstruction.
