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Giant Antarctica Iceberg Puts Nasa On Alert
An iceberg bigger than Chicago is being monitored by Nasa after breaking into the ocean off Antarctica.
The sheet, known as B31, is one of the biggest on the planet at 255 square miles (660 sq km).
Nasa has been monitoring Antarctica's Pine Island Glacier since a crack was spotted in 2011, amid fears any iceberg could contribute to rising sea levels.
B31, which is about a third of a mile (500m) thick, is not currently on any major shipping routes.
However, with winter approaching in the area, it could become difficult to track.
"The iceberg is now well out of Pine Island Bay and will soon join the more general flow in the Southern Ocean," Grant Bigg, from the University of Sheffield, said in the Nasa statement.
"We are doing some research on local ocean currents to try to explain the motion properly. It has been surprising how there have been periods of almost no motion, interspersed with rapid flow."
An iceberg this big could take a year or more to melt, Robert Marsh, a scientist at the University of Southampton, said in an interview last year.
The largest iceberg ever recorded was called B15 and had an area of 4,250 square miles (11,000 square kilometres) - about the size of Jamaica.
It broke off Antarctica's Ross Ice Shelf in March 2000 and still exists in several parts around the Antarctic.