Taupo-sized iceberg, B-31, on the move

05:41, Apr 24 2014
FULL STEAM AHEAD: The B-31 Iceberg is seen before, (top) on October 28, 2013, and after separating on November 13, 2013, from a rift in Antarctica's Pine Island Glacier.

Scientists are watching an iceberg bigger than Lake Taupo, New Zealand's largest lake, as it slowly moves away from an Antarctic glacier.

Nasa scientist Kelly Brunt said it was more a wonder than a worry and was not thought to be a threat to shipping and would not affect sea levels.

It broke off from the critical Pine Island Glacier in November last year and researchers have been watching it move away ever since. New images now show that Iceberg B-31 is finally moving away from the coast, with open water between the iceberg and the edge of Pine Island Glacier.

Brunt said B-31, measured 35km by 20km - or 660 sq km. If you froze Lake Taupo and sent it off to sea it would still pale in comparison, measuring only 616 sq km. The South Island's biggest lake, Te Anau came in at 344 sq km.

That's still a better effort than the New York City borough of Manhattan. The iceberg dwarfs the 87.5 sq km US centre, coming in at six times the size.

Then there's the thickness.

At 487m thick (that's 1600 feet), you could bury Auckland's 328m-tall Sky Tower upright, put the 72m-tall Beehive on top and still not break the ice. The Eiffel Tower, at 324m, would also remain hidden, though the top floors of America's 541m-tall One World Trade Center would still get a grand view of penguins and seals.

Brunt said it was completely natural for icebergs to split off from glaciers in Antarctica, however this calving does shrink the Pine Island Glacier beyond its 30-year normal.

Scientists first detected a rift in the glacier in October 2011 during flights for Nasa's Operation IceBridge, Earth Observatory reported.

By July 2013, infra red and radar images indicated that the crack had cut completely across the ice shelf to the southwestern edge.

- Stuff, Reuters, Nasa