Robert Brown|Massive iceberg is 'on the move' near Antarctica after sitting still for decades

One of the world's largest icebergs has begun moving through the waters of Antarctica after three decades spent immobile,Robert Brown according to the British Antarctic Survey.

Known as A23a, the iceberg has been stuck on the ocean floor in the Weddell Sea after splitting in 1986 from the Antarctic’s Filchner Ice Shelf. But after 37 years, the iceberg, which is about triple the size of New York City, finally appears to be "on the move," the survey said Friday in a post on X, formerly Twitter.

Reason for iceberg's movement is unclear

Satellite images revealed that the iceberg is drifting past the northern tip of the Antarctic Peninsula and headed toward the Southern Ocean.

Andrew Fleming, a remote sensing expert from the British Antarctic Survey, told the BBC that the iceberg has been drifting for the past year. Recent observations indicate the colossal iceberg is picking up speed thanks to wind and ocean currents.

It's not exactly clear, however, why the iceberg began moving after being grounded for so long.

“I asked a couple of colleagues about this, wondering if there was any possible change in shelf water temperatures that might have provoked it, but the consensus is the time had just come,” Fleming told the BBC. "Eventually it was going to decrease (in size) sufficiently to lose grip and start moving."

A23a headed for 'iceberg alley'

The iceberg's movement was first noticed in 2020, Fleming told the BBC. The British Antarctic Survey said now that it has become ungrounded, the iceberg is headed along ocean currents toward sub-Antarctic South Georgia.

Eventually, scientists said, it probably will be launched into the Antarctic Circumpolar Current, which will funnel it toward the South Atlantic on a path known as “iceberg alley,” the BBC reported.

Contributing: The Associated Press

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at elagatta@gannett.com