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Glacier prompts tsunami warning
Visitors to the Tasman Glacier at Mount Cook are being warned to stick to high vantage points, with a tsunami on the way if the rain in the area keeps up.

Authorities say the iceberg in the lake has risen another 20 metres out of the water and when it breaks off, a process called "calving", it will lead to a big surge of water.

"It's lifting off the bottom of the lake and starting to move upwards. At some stage it's going to break off and we're going to have some of the most significant iceberg calvings on the lake since it was formed," said Department of Conservation manager Richard McNamara.

Aoraki Tourism general manager Denis Callesen said the surge won't be like that you'd get on a beach.

"It will be a rolling wave, rather than a breaking wave," he said.

The event has been caused by 250 millimetres of rain falling in 72 hours. Callesen said the extra water has lifted the face of the glacier, and three million tonnes of ice could end up in the lake.

Callesen said part of the huge block of ice, which is nearly 30 kilometres long, 600 metres deep and 1.6 kilometres wide, will break off at some point and when it does it will be "a very significant tsunami coming down the lake".

If the iceshelf was to go in one hit, it would be the single biggest change to the lake in its 30-year history.

"It's up to nature when it happens," he said. "But another weather event is due tomorrow."

Callesen said the last time this happened, last February, a surge of water around three metres high was recorded.

The Department of Conservation is putting up signs warning people to stay away from the water edge, and boaties should keep a safe distance, but there are no houses in the area so property won't be affected

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Op dinsdag 3 augustus 2010 16:40 schreef Frutsel het volgende:
Nog twee voorbeelden van 'Glacier Calving'

Tsunami Greenland - Tsunami Groelândia 1995

The Collapse of a Glacier

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Spectacular Calving sets ice crashing off glacier

Up to 50 million tonnes of ice has come crashing down off the South Island's Tasman Glacier in a dramatic show of nature that has created a series of new icebergs.

The ice "calving" off the glacier's terminal face has left at least 20 significant icebergs, measuring at least 50m by 50m above the waterline, in the Tasman Glacier Terminal Lake.

"The scale of what's happening here is just enormous," said Denis Callesen, general manager of tourism for Aoraki/Mt Cook Alpine Village.

"The biggest berg is about 300m by 200m and 40m high - and that's only the 10 per cent of the berg we can see - 90 per cent is below the waterline.

"These bergs now take on a life of their own, flipping, turning and moving as natural forces take action."

The process began this month when the terminal face rose 20 to 40m, thanks to a downpour which lifted millions of tonnes of ice from the water across the entire 600m width of the face.

On August 18, a small section of that ice calved off, resulting in one large iceberg separating from the face. Then at the weekend the rest of the uplifted ice broke away in the biggest calving in the lake's 35-year history.

Glacier Explorers, which takes passengers on cruises on the lake, will resume operations ahead of schedule next month to take advantage of the new icebergs.

"We are expecting the most spectacular season ever here, with stunning viewing of nature in action," said Mr Callesen. "Visitors ... will be in for a trip of a lifetime."

quote:

Tasman Glacier triggered 3 meter high tsunami?
Up to 50 million tonnes of ice has fallen off New Zealand's largest glacier.

The Tasman glacier has changed from a U shape to an L after shedding the ice.

Mount Cook Alpine Village general manager Denis Calleson says a trail of huge icebergs has been left behind.

One is believed to be the largest in a fresh water lake outside Antarctica.

The event was thought to have triggered a three-metre-high tsunami in a remote part of Mount Cook National Park.

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Op woensdag 25 augustus 2010 14:02 schreef rubje het volgende:
ik zie teveel topics met allemaal natuur onheil.... nadert het einde vd wereld?

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Gletsjer breekt af na beving Nieuw-Zeeland
CHRISTCHURCH - Kort na de aardbeving in Nieuw-Zeeland van dinsdag is een enorm stuk ijs afgebroken van een grote gletsjer in dat land. Ruim 30 miljoen ton ijs stortte in een meer en veroorzaakte een half uur lang golven van wel drie meter hoog.

Volgens medewerkers van het natuurgebied bij de Tasman Gletsjer werd al langer gedacht dat het blok ijs af zou gaan breken. De beving met een kracht van 6,3 op de schaal van Richter gaf het stuk gletsjer van ongeveer een kilometer lang het laatste zetje.

De aardbeving zorgde voor hevige trillingen die twee keer een minuut aanhielden. Die trillingen waren bij de gletsjer, ongeveer 150 kilometer vanaf het epicentrum, een stuk milder. „Binnen een minuut na de beving hoorden de medewerkers bij het meer een geluid als een geweerschot en kort daarna begon het ijs af te breken”, aldus Denis Callesen, een van de medewerkers.

In het meer drijven nu flinke ijsschotsen, sommigen tot wel tweehonderd meter lang.