A massive iceberg weighing more than one trillion tons has broken away from western Antarctica, according to a UK-based research team.br br Scientists announced that the 6-thousand-square-kilometre (2,300 square miles) iceberg had come loose, after satellites detected it had calved off the Larsen C ice shelf on the Antarctic Peninsula.br br Aerial footage filmed in February showed a giant crack which had formed between the iceberg and the shelf.