No heightened risk of tsunami strike
If a tsunami struck Timaru it is likely to be between six and eight metres high, according to a hazard review by Ministry of Civil Defence and Emergency Management.
This is the first major update of the science encompassing the whole of New Zealand's coastline since 2005.
There is no local tsunami source scientists are aware of.
The biggest threat is from the South American continent which offers Timaru a 14-hour warning window.
The tsunami would be tracked via monitoring buoys across the Pacific Ocean.
Civil Defence emergency management officer Lamorna Cooper said the time lag would allow emergency services to mobilise and activate evacuation plans.
The message, to be prepared, was the same for a tsunami, snow or flood and did not change from event to event, she said.
"We are fortunate most areas affected are well identified and are low residential areas," Ms Cooper said.
If an earthquake is felt "it's a heads up" though and it is unlikely to be offshore.
Though the probability of a tsunami has not changed the maximum possible size of one in some areas it has increased, according to the report.
The main areas where tsunami caused by local and regional sources pose a greater hazard than previously understood include: the coasts of Northland, the north-west part of the Auckland region, Great Barrier Island, Coromandel Peninsula, Bay of Plenty, the East Cape of the North Island, parts of the Wairarapa coast, Southland, Stewart Island, Fiordland and Westland.
The tectonic plates in Japan are converging twice as fast as those around New Zealand, which suggests the interval between the largest earthquakes on our local plate boundaries could be more than 2000 years.
However, New Zealand's historical record of 200 years, is not long enough to provide accurate reported information.
During that time the country has experienced about 10 tsunami of five metres or more.
For more information visit: civildefence.govt.nz.
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