In the Hollywood blockbuster "The Core," the planet's core suddenly stops spinning, causing the Earth's magnetic field to collapse. Then deadly microwaves kill the Coliseum and melt the Golden Gate Bridge.
While "almost everything in the film is wrong," says seismologist Justin Revenaugh of the University of Minnesota, it is true that the earth's magnetic field shields the planet from deadly and destructive solar radiation. Without them, solar winds could deprive the earth of its oceans and atmosphere.
But the magnetic field of the planet is not static.
Earth's magnetic north pole (which does not correspond to the geographic north) has led scientists to a kind of chase in the last century. It moves an average of 30 miles north each year.
This movement made the World Magnetic Model (WMM), which tracks the field informed compasses, GPS on smart phones and navigation systems in aircraft and ships – inaccurate , With the next scheduled update of the WMM not scheduled before 2020, the US military demanded an unprecedented early update to accommodate the accelerated Gambol of the magnetic North.
Authors of a new study have now gained insight into why the magnetic north could move and learn to predict these shifts.
Earth's magnetic field is due to the vortex of liquid nickel and iron in the outer core of the planet, about 1,800 miles below the surface. Anchored by the northern and southern magnetic poles (which tend to shift and even reverse every million years), the field increases and decreases, depending on what is going on in the core.
Periodic and sometimes random changes in the distribution of this turbulent liquid metal can cause peculiarities in the magnetic field. If you think of the magnetic field as a series of rubber bands that pass through the magnetic poles and the Earth's core, then changes in the core will take different places on different rubber bands.
These geomagnetic tugs then influence the migration of the northern magnetic pole and can even cause it to deviate wildly from its current position.
Read more: The Earth's northern magnetic pole has moved – which means what that means for our navigation systems.
The prediction of these magnetic field shifts has been a challenge so far. In the new study, geophysicists Julien Aubert and Christopher Finlay attempted to simulate the physical conditions of the Earth's core by having supercomputers perform calculations worth 4 million hours.
The researchers knew that the movement of heat from inside the planet to the outside could affect the magnetic field. Generally this happens at a speed of 6 miles per year. However, their results have shown that at the core there are sometimes pockets of liquid iron that are much warmer and lighter than the surrounding liquid. If the difference between these hot, less dense liquid pieces and their colder, denser counterparts is large enough, the warm liquid can rise very quickly.
This rapid movement then triggers magnetic waves that are heading toward the surface of the nucleus, causing geomagnetic shocks.
"Think of these waves as the vibrating strings of a musical instrument," Aubert told Business Insider.
The magnetic north is important for navigation models.
The control of the magnetic north is essential for European and American military, since their navigation systems use the WMM. Commercial airlines and smartphone GPS apps also rely on the model to help pilots and users identify their locations and navigate accordingly.
Therefore, the British Geological Survey and the National Oceanic and Atmospheric Administration (NOAA) update the WMM every five years. The US military mandated early update was completed on February 4.
But even with these regular updates, geomagnetic shocks make it hard to keep the model accurate, Aubert said.
The new model of his group could solve this problem by predicting the Earth's magnetic field strength could develop.
"Over the next few years, it is believed that our groups […] should actually be able to capture past impacts and predict future ones with improved accuracy," said Aubert.
Could the magnetic field ever collapse?
Earth's magnetic field shields its atmosphere, which "does much of the work of keeping out solar radiation," as Revenaugh put it. If we lost our magnetic field, we would eventually lose our atmosphere.
According to Revenaugh, however, this is highly unlikely, as the Earth's core would never stop turning.
Even if the field collapsed, the devastating effects of "The Core" (people with pacemakers, runaway thunderstorms, runaway thunderstorms, destroyed national landmarks) would not follow.
A much more likely scenario, according to Revenaugh, would reverse the magnetic poles as it did 780,000 years ago. If such reversals happen (there were several in Earth history), the magnetic field drops to about 30% of its full strength, he said.
Although this is a distant scenario, Revenaugh added that it is still important to improve the understanding of scientists for the magnetic field today.
"The better we can model it, the better we can understand what it's about," he said.