A piece of Antarctic twice as big as New York could soon come off

This would create an iceberg more than twice as big as New York City (which is about 302 square miles).

NASA did not say when it would happen, except on its website that it was about to happen.

The Brunt Ice Shelf advances in the Weddell Sea south of South America. Two cracks could eventually lead to breakage.

A crack, called Halloween, appeared for the first time in October 2016 in the northern part of the plateau and continues to move to the east.

The other crack, which crosses the center of the plateau to the north, has remained stable for more than three decades. Then, the acceleration started at a rate of about 2.5 miles per year.

When the two cracks meet, the ice breaks.

Even though the iceberg that it creates seems huge, it is not actually in accordance with Antarctic standards. But it will still be important.

"This is perhaps the biggest iceberg to come out of the Brunt Ice Shelf since sightings began in 1915," NASA said on its website. "Scientists are looking to see if the loss will trigger new changes in the shelf and could even become unstable or break."

CNN interactive: Protecting the Antarctic

Concerns for safety

There is also concern about the safety of people working on the pack ice, including researchers at Halley Station in the British Antarctic Survey. It is a major base for terrestrial, atmospheric and spatial research.

NASA said the station was active all year, but had closed twice in recent years due to unpredictable changes in ice.

This ice cracking, or calving, is part of the life cycle of an ice shelf, but these recent changes are not familiar to this region.

"We do not have a clear idea of ​​what determines the periods of advancement and retreat of the plateau at times of calving," said NASA glaciologist Chris Shuman. "The likely future loss of ice on the other side of the Halloween crack suggests that greater instability is possible, with an associated risk for (Halley Station)."