The field changes as the molten metals surrounding the earth’s solid iron core churn and flow, creating electric currents and a corresponding magnetic field. As a result, the magnetic poles tend to shift slightly as a matter of course.

However, researchers don’t know what’s causing the magnetic field to now move so quickly.

The north magnetic pole sped across the International Date Line last year at a rate of 55 km per year, more than three times as fast as it moved before the mid-1990s. Now located in the Eastern Hemisphere, it’s moving away from Canada and approaching Siberia.

Scientists think a high-speed jet of liquid iron under Canada could be responsible for the pole’s movement, weakening the magnetic field below and allowing Siberia to draw over the pole, Nature reports.

“The location of the north magnetic pole appears to be governed by two large-scale patches of magnetic field, one beneath Canada and one beneath Siberia,” University of Leeds geomagnetist Phil Livermore told a recent American Geophysical Union meeting. “The Siberian patch is winning the competition.”

In general, the World Magnetic Model (WMM) is updated at five-year intervals to ensure modern navigation keeps up with the changes in the Earth’s magnetic field. It was due to be reconfigured next in 2020, but was so out-of-whack by 2018 that a more urgent update was needed.