An iceberg twice the size of Toronto just broke off Antarctica A massive iceberg spanning 1,270 square kilometres has broken off from the Brunt Ice Shelf. That's a piece of ice almost exactly twice the size of this city (Toronto is around 630 square kilometres) drifting off Antarctica. Glaciologists with the British Antarctic Survey's (BAS) Halley Research Station have been expecting this big calving event to happen for at least a decade. The North Rift has been moving northeast since November and finally cracked apart from the shelf on February 26. Photo via British Antarctic Survey's Halley Research Station. Scientists first detected growth of vast cracks in the ice years ago.