Video | Business Headlines | Internet | Science | Scientific Ethics | Technology | Search

 


NIWA: Cook Strait Canyon starts to spill its secrets

NIWA: Cook Strait Canyon starts to spill its secrets

Preliminary results from the first comprehensive survey of the Cook Strait Canyon seabed have begun to reveal tantalising scientific secrets about New Zealand’s largest underwater canyon.


Underwater video footage taken using a deep-towed imaging system (DTIS) shows life on the seafloor of the canyon, including a king crab and brittle stars.

Last month marine geology and biology scientists onboard NIWA’s research vessel Tangaroa spent a week collecting sediment cores, rock samples and video footage and photographs of the seafloor in the canyon system.

One of the largest underwater canyon systems in the world, the Cook Strait Canyon starts just 10 kilometres off the Wellington coast and plunges to 3 kilometre depths south of Cape Palliser. Initial bathymetric mapping by NIWA showed that the canyon is scarred by more than 150 submarine landslides and many active faults. But, until now, very little has been known about what caused those landslides and the hazards they may pose, or even what lives there.

Three landslides in the upper canyon were sampled on the latest voyage. Initial results show that one of these landslides in particular occurred recently, and may have been caused by the magnitude 8.3 Wairarapa earthquake in 1855. The similarity of this landslide to others in the canyon suggests that many of these occurred during this large earthquake. The Wairarapa earthquake caused widespread landslides on land, uplifted the Wellington waterfront and generated a moderate tsunami.

NIWA Marine Geologist Dr Joshu Mountjoy says “we have long suspected that many of the landslides we see occurred during the 1855 event. We have never had any data to support this so it is really exciting to be getting to the point where we can attribute landslides to this earthquake with certainty.”

One of the canyon’s three main arms appears to be inactive at the moment and is predominantly filled with mud. However, sediment cores taken from the Nicholson and Cook Strait arms of the system, indicate these canyons are much more active, with repetitive sediment flows occurring. Where these canyons merge at around 1,200 metre depths, towed camera images showed jagged blocks of rock lying on the canyon floor. These may have fallen off the canyon walls, which are more than one kilometre high, or been excavated out of the canyon floor by the current.

“Carbon dating of the sediment cores and rock samples collected will give us more information about how old the sediment is in the canyon floor and the age of the landslides. That helps us assess whether activity in the canyon is caused by earthquakes, tidal currents or other sediment processes,” Dr Mountjoy says.

“Some landslides in the system are huge, ranging in volume from 2.5 million cubic metres to approximately ten cubic kilometres size, and they certainly have the potential to generate hazardous tsunami. We are now getting a clearer idea of how often the landslides might occur and why.

“Most importantly we will be able to feed this new data on the previous landslides into work NIWA and GNS Science are doing together to quantify the tsunami generation potential of future landslides in the canyon system, ensuring New Zealand is better prepared to respond to natural disasters in the future. ”

Underwater images collected during the survey have also revealed more about the communities of animals that live in the canyon system.

“From the images it appears that very little life occurs on the canyon floor in the active part of the canyon system,” says NIWA Principal Scientist Dr Ashley Rowden. “But in the apparently inactive Wairarapa arm we saw an abundance of brittle stars, some large king crabs and burrows and other signs that numerous creatures live beneath the surface of the seabed.”

“By comparing the biological communities in the active and inactive areas of the canyon system, we can begin to understand how different creatures are affected by disturbances such as landslides and other sedimentary processes. All of this information feeds into wider research to understand the underwater processes that maintain the diversity of species living in deep-sea environments.”

The research is funded by the Ministry of Science and Innovation under the “Consequences of Earth Ocean Change and Impacts of Resource Use on Vulnerable Deep Sea Communities” programmes, and through the Natural Hazards Research Platform.

© Scoop Media

 
 
 
 
 
Business Headlines | Sci-Tech Headlines

 

Balance Of Trade: NZ Posts Trade Deficit In October On Falling Dairy Exports

New Zealand’s posted its largest monthly trade deficit for October in six years, while narrowing the shortfall from September, led by a fall in dairy exports to China while all main imports into the country rose. More>>

ALSO:

Gigatown Winner: Plenty Of Positives For Dunedin

Although the city has taken the Gigatown title, along with new ultrafast 1Gbps broadband and funding for $700,000 worth of UFB-related initiatives across the community, Mr Cull says Dunedin has gained so much more through its involvement. More>>

ALSO:

R18: The Warehouse Group Praised For Removing Games

The decision by New Zealand’s largest retailer The Warehouse Group (TW Group), to withdraw stocks of the latest version of Grand Theft Auto V (GTA V) and other R18 games, has been praised by advocacy group Stop Demand Foundation. More>>

ALSO:

Air NZ Wine Awards: Victory For Villa Maria As Pinot Noir Thrills

It was a night to remember as Villa Maria Estate picked up one of the highest accolades of the evening, the O-I New Zealand Reserve Wine of the Show Trophy, at the 28th Air New Zealand Wine Awards. The Villa Maria Single Vineyard Southern Clays Marlborough ... More>>

ALSO:

Future Brighter Money: RBNZ Releases New Bank Note Designs

New Zealand’s banknotes are getting brighter and better, with the Reserve Bank today unveiling more vibrant and secure banknote designs which will progressively enter circulation later next year. More>>

ALSO:

Get More From Scoop

 
 
Standards New Zealand

Standards New Zealand
 
 
 
 
 
 
 
 
Sci-Tech
Search Scoop  
 
 
Powered by Vodafone
NZ independent news