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Special Interest Forums => Science, Space & Technology => Topic started by: Kiwithrottlejockey on February 14, 2011, 10:30:02 pm



Title: Wellington's huge undersea canyon
Post by: Kiwithrottlejockey on February 14, 2011, 10:30:02 pm

Scientists seek secrets of abyss

Wellington's canyon unexplored

By SHANE COWLISHAW - The Dominion Post | 5:00AM - Monday, 14 February 2011

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INTO THE DEEP: Joshu Mountjoy will lead a team of scientists on research ship Tangaroa to study quake risks
from the Cook Strait trench. — KENT BLECHYNDEN/The Dominion Post.


NIWA SCIENTISTS are set to explore the unknown depths of Cook Strait in research that could save thousands of Wellingtonians' lives.

The 10-strong team, led by ocean geology scientist Joshu Mountjoy, will use new technology on research ship Tangaroa to investigate the mysterious Cook Strait Canyon.

The canyon, 10 kilometres off Wellington's south coast, is one of the deepest in the world, plunging to depths of 3km south of Cape Palliser.

Despite its size and relatively accessible location, little is known about the canyon, its biology and the landslides and active faults that scar its surface.

Dr Mountjoy said the landslides observed in the canyon were huge — about four times the size of Wellington's Mount Victoria — and had the potential to generate massive tsunamis that could smash into the capital within minutes of an earthquake.

The massive slips were discovered in 2009 using hi-tech underwater scans, revealing volumes of moving material from 2.5 million cubic metres in size to 10 cubic kilometres.


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COOK STRAIT CANYON: Plunges to 3000m deep.

Dr Mountjoy said it was hard to fathom the sheer size of the slips when compared with ones seen above water.

"These are just far and away bigger, these are hillsides that are coming down."

This voyage will be the first time samples have been collected in the canyon and will again use impressive technology.

A dynamic positioning system will allow the team to take accurate sediment core and rock samples, and a deep-towed imaging system will use a high-definition camera to provide images of the sea floor in the canyon for the first time.

There was little research about the potential of tsunamis from underwater landslides but the risk was real, Dr Mountjoy said.

In 1998 a magnitude 7 earthquake in Papua New Guinea triggered a tsunami that killed more than 2200 people. The cause of the giant wave was later pinpointed to an underwater landslide.

The size of the landslides in the Cook Strait canyon was of a comparable nature, so the research would be an important tool to begin understanding where and when a wave could hit Wellington, Dr Mountjoy said.

"With an earthquake in Chile you can have a nice warning time where you can get everyone [here] prepared, but with the landslides it's likely to be minutes."

Using the research gained from the voyage, a team of Niwa and GNS Science experts will work together to better understand the tsunami risk to coastal communities around Wellington.

The sea-floor camera will also provide the first images of lifeforms at the bottom of the canyon.


http://www.stuff.co.nz/dominion-post/news/4652172/Scientists-seek-secrets-of-abyss (http://www.stuff.co.nz/dominion-post/news/4652172/Scientists-seek-secrets-of-abyss)