Mother Nature is set to put on a spectacular show at Aoraki Mount Cook’s Terminal Lake with what could be the biggest ‘calving’ of ice from the glacier face ever seen.
A 20 to 40-metre rise in the height of the Tasman Glacier's terminal face, thanks to a 250 millimetre downpour of rain over the weekend, has lifted thousands of tons of ice from the water across the entire 600m width of the face.
Aoraki Mt Cook Alpine Village Ltd tourism general manager Denis Callesen said the pressure of ice lifting out of the water on the glacier face could lead to the most spectacular break off of a giant slab of ice or ‘calf’ into the lake ever seen.
“It’s incredible to see this very distinct line of ice that’s risen out of the water, we’ve never seen that happen before across the whole face,” he said.
“Sometime soon there’s going to be a massive calving. If the whole lot goes together, upwards of 10 million tons of ice could break off in one hit. When that happens we’ll have one or more icebergs launched into the lake, creating a huge surge of water. It will be a truly impressive sight.”
The Glacier Explorers season is due to open in the next few weeks and Mr Callesen said the 2010/2011 season could be one of the most spectacular for iceberg viewing in the 30 year history of the lake.
“Passengers this year are likely to get a trip of a lifetime as a result of the calving. Obviously safety is the ultimate priority so when we start visitor trips in the coming weeks, boats touring the glacier won’t be allowed to go within 1.5 kilometres of the terminal face.
“When swells happen, either by the calving itself or any subsequent iceberg rollovers, if boats are out on the lake the crew is fully trained to deal with any situations that may arise. The guide on the day makes the decision as to how close to get to any icebergs, based on iceberg or glacier stability and weather conditions.”
In February 2009 the largest single iceberg to date -- estimated to be 250m long by 250m wide by 80m high – plunged from the terminal face into the lake and was christened ‘The Perfect 10’ by Glacier Explorers Operations Manager Bede Ward, whose company takes visitors on boat trips to view the Tasman Glacier face from the water.
A previous significant one was christened ‘Sir Ed’ after it calved on 11 January 2008, the day Sir Edmund Hillary passed away.
Mr Ward said icebergs were being named in order to track and communicate changes and locations, and because it made for fascinating stories for passengers.
“Since the Terminal Lake began forming in 1973, the Tasman Glacier’s retreat has noticeably quickened because the lake is expanding all the time and is causing a more rapid melt of the terminal face. I think we may be looking at major calving from the terminal face as an annual event now.”