A 1,270 square kilometre iceberg - roughly the size of Co Monaghan (1,295 km²) - broke away from the Brunt Ice Shelf in Antarctica yesterday morning.

The calving took place almost a decade after scientists from the British Antarctic Survey at the Halley Research Station first detected cracks in the 150m thick ice shelf.

The first indication that a calving event was imminent came in November when a new chasm – called North Rift – headed towards another large chasm near the Stancomb-Wills Glacier Tongue 35km away.

North Rift is the third major crack through the ice shelf to become active in the last decade.

During January, this rift pushed northeast at up to 1km aday, cutting through the floating ice shelf. 

The iceberg was formed when the crack widened several hundred metres in a few hours yesterday morning, releasing it from the rest of floating ice shelf.

British Antarctic Survey footage shows a flyover of the North Rift ten days before the calving.