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

 

Drones: First Certificate Issued Under New UAV Rules

Transport Minister Simon Bridges and Associate Transport Minister Craig Foss say the first certified flight of an unmanned helicopter under new aviation rules is a great example of how they can enable commercial use. More>>

ALSO:

GE Swedes And Cow Deaths: Plant Analysis Backs Up Earlier Advice

The industry body is recommending that farmers do not feed Herbicide Tolerant (HT) swedes to cows in spring when the animals are in late pregnancy or early lactation. DairyNZ is also advising caution if farmers are considering other leafy varieties. More>>

ALSO:

Statistics: Dairy And Travel Still Our Largest Export Earners

New Zealand earned $2.3 billion more from exports than we spent on imports during the year ended June 2015... total exports of goods and services were $67.5 billion, while total imports were $65.1 billion. More>>

ALSO:

Approval: Air New Zealand And Air China Launch New Alliance Route

Air New Zealand and Air China have today launched joint sales for a new daily direct service between Auckland and Beijing after receiving approval from New Zealand Minister of Transport Hon Simon Bridges to form a strategic alliance. More>>

ALSO:

Money Trading: FX Trader Jin Yuan Finance Warned Over Lack Of Monitoring

Jin Yuan Finance, an Auckland-based foreign exchange trader, has been warned over its lack of anti-money laundering processes in place in the first public notification by the Department of Internal Affairs. More>>

ALSO:

Auckland Surge, Possible Peak: House Values Accelerate At Fastest Annual Pace In 8 Years

New Zealand residential property values rose at their fastest annual pace in eight years in August, pushed higher by overflowing demand in Auckland, which is showing signs speculators think it has reached its peak, according to Quotable Value. More>>

ALSO:

Cash Money: Reserve Bank Launches New $5 And $10 Banknotes

The $5 and $10 final banknotes were revealed at an event at the Bank in Wellington, and will start to be released from mid-October 2015. More>>

ALSO:

Truck Sales Booted: Commerce Commission Files Charges Against Mobile Trader

The Commerce Commission has filed charges against a mobile trader, or truck shop operator, claiming he obtained money from customers by deception and never intended to supply them with the goods they paid for. More>>

ALSO:

Get More From Scoop

 
 
 
 
 
 
 
 
 
Sci-Tech
Search Scoop  
 
 
Powered by Vodafone
NZ independent news