'Largest ever' iceberg calves into glacier lake
A major 'calving' event on the front face of New Zealand's Tasman Glacier has created the largest-ever iceberg seen on the Tasman Glacier Terminal Lake.
The calving - believed to have happened in the early hours of Saturday morning, saw the entire 650m-wide front face of the Tasman Glacier in Aoraki Mount Cook National Park break away into the lake.
The ice broke into around 20 huge icebergs, including one which Glacier Explorers Operations Manager Bede Ward described as "the largest ever" by quite some way.
"The last major calving we had was just over a year ago which was estimated at 30 million tonnes of ice breaking off the glacier," he said.
"This is much, much larger. There's one iceberg which surpasses the last largest-ever single iceberg (nicknamed Taniwha) we've ever had on the lake by quite some way.
"The sheer walls of this iceberg reach 40 to 50 metres in height above the waterline, and would almost certainly be 200 to 250 metres beneath the water line. That's simply enormous."
Mr Ward said the timing of the calving was also a huge coincidence, as the Tasman Glacier Lake had a similar calving of this scale just five minutes after the Christchurch earthquake two years ago.
"The Tasman Glacier has been unusually quiet for the past 12 months with only small calvings suggesting the glacier had maybe started to slow down," he said.
"That's proven to the contrary after it released the 'mother lode' yesterday."
Mr Ward said the icebergs created by the calving would make for "fantastic viewing" for visitors on board Glacier Explorers Mac Boats, which take passengers out on the lake to view towering ice cliffs and the huge 'bergs'.
"It's an extraordinary opportunity to view nature in action, simply spectacular," he said. "Guests who have been out with us today couldn't believe their luck, and the icebergs will be around for months to come."
No-one witnessed the calving as it happened at night.