Tsunami threat in Kaikoura

21:32, Mar 19 2014
Kaikoura peninsula
HAZARDOUS: ECan's report said there was potential for large landslides to occur in shallow water, very near the south coast of Kaikoura Peninsula.

If a tsunami was triggered in the Kaikoura canyon, there would be "only minutes" for the town's residents to get to higher ground, Environment Canterbury says.

Parts of Kaikoura township were also likely to end up under water if a large South American earthquake set off a tsunami.

Scientists have been working off the east coast of the South Island as part of a region-wide tsunami hazard investigation. A report yesterday released by ECan concluded there was potential for large landslides to occur in shallow water, very near the south coast of Kaikoura Peninsula.

ECan commissioner Donald Couch said there was a tsunami risk to the Kaikoura township and coast which would "need to be managed".

"A tsunami generated in a South American earthquake will take several hours to get here, which gives us some warning, but if a tsunami is triggered in the Kaikoura Canyon, there will be only minutes to get to higher ground."

Modelling based on the 1868 Aria (South America) tsunami showed that a South American- generated tsunami would flood parts of Kaka and Weka streets in South Bay, and Fyffe and Wakatu Quays in Kaikoura. The second wave would be the largest, travelling at about a metre a second.


Kaikoura Mayor Winston Gray said the report showed "nothing new". "It's a fact of life, the whole coast will be inundated to a certain degree. Anyone living in that area is aware of it."

Gray said the council was investigating extra preventative measures - including a "flotation device that goes in the water to give you a quicker response time" - but they would focus mainly on educating people of the risks.

"Our role is to make sure people are aware and alert to [the risk]. If you feel a quake anywhere that you think is more than a minor, immediately go to high ground."

The council held a Preparedness/Tsunami Information road show last night and another would take place tonight.

NIWA marine geologist Dr Joshu Mountjoy said several shallow-water sediment bodies at the edge of the Kaikoura canyon posed a "potentially hazardous scenario".

"It's very important to understand how big these tsunami could be and to determine where and when they might occur."

Couch said Kaikoura residents should move to higher ground immediately if they felt an earthquake so strong they could not stand up, or one that went on for more than a minute.

The Kaikoura Canyon investigation is part of a programme with ECan to understand the hazard posed to the Canterbury coastline from tsunami. The next two phases of the research includes modelling of new landslide- tsunami events, and is due for completion later this year and next year.

The Press