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A Nasa photograph shows how an iceberg is close to splitting from Antarctica. - Source: Fairfax
A Nasa photograph shows how an iceberg is close to splitting from Antarctica. - Source: Fairfax
Amazing Nasa photographs shows how an iceberg the size of Manhattan is close to splitting from Antarctica.
The 30-kilometre crack in Pine Island Glacier's ice was set to eventually extend across the surface and calve a giant iceberg.
The rift was 80m wide and 60m deep, and when the ice breaks off it would cover about 900 sq km.
The pictures, taken by Nasa's Terra spacecraft in November 2011 and only released overnight, illustrates how the crack had grown about 2km in one month.
It was taken after scientists in Antarctica discovered the rift in mid-October and was first photographed by Nasa's Operation Ice Bridge.
The Pine Island Glacier runs westward along the Hudson Mountains towards the Amundsen Sea.
It last calved a significant iceberg in 2001, and scientists had speculated it was primed to calve again.
Pine Island has scientists' attention because it is both big and unstable - they have called it the largest source of uncertainty in global sea level rise projections.
But Nasa said the calving was part of a natural process for a glacier.
"We are actually now witnessing how it happens and it's very exciting for us," Ice Bridge project scientist Michael Studinger said, when the crack was first surveyed.
"It's part of a natural process but it's pretty exciting to be here and actually observe it while it happens. To my knowledge, no one has flown a lidar instrument [for measurement] over an actively developing rift such as this."
Ice Bridge is a six-year airborne survey of the Earth's polar ice aimed at yielding an unprecedented three-dimensional view of Arctic and Antarctic ice sheets, ice shelves and sea ice.
The scientists' primary goal was to monitor the area, year after year, to gather meaningful and accurate data of any change.
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