A shift of the magnetic north pole earlier this year generated widespread interest and some concern, but experts from the U.S. Geological Survey (USGS) said regular, natural process is nothing to be worried about.

The pole shifted 40 miles towards Russia around the first of the year. The shift can be a nuisance for planes that use old-fashion compasses for navigation, but Jeffrey Love, USGS advisor on geomagnetic research, said the earth’s magnetic poles are in constant flux due to changes in the earth’s core.

“It’s not really an event I would say—it’s a continuous process,” said Love. “The Earth’s magnetic pull and the shape of the geomagnetic field is changing all the time.

“I would not say this is significant or unusual,” he added. “It is an ongoing process, which is an interesting phenomenon.”

Love said the shifting is caused by liquid iron at the Earth’s core, which is perpetually in motion. That motion creates electric currents in the core, which in turn, creates magnetic fields. The motion of the Earth’s core changes over time and therefore, the planet’s magnetic fields change as well.

But the shift had at least one real effect. In Florida, planes were grounded as Federal Aviation Administration officials forced workers to repaint the signs at Tampa International Airport’s primary runway to account for the shift The busiest runway at Tampa International will be re-designated 19R/1L on aviation charts. It had been 18R/36L, indicating its alignment along the 180-degree approach from the north and the 360-degree approach from the south, explained an article in the Tampa Tribune detailing the changes.?

Adjustments are not being required at all airports, however, because the changes are manifest differently at different points on the surface of the planet.

FAA officials were unsure how often a move like this was necessary.

“It happens so infrequently that they wouldn’t venture a guess,” Paul Takemoto, a FAA spokesman, told Fox News. Takemoto said that the changes will have no effect on passenger safety.

Love said that shifting had nothing to do with the recent phenomenon of large numbers of dead birds and fish being found at several locations worldwide.