NZ 'poorly prepared' for tsunami

New Zealand's preparedness for a tsunami is exactly the same as in Samoa (pictured) before the disaster there, an expert says. Photo / Brett Phibbs
New Zealand's preparedness for a tsunami is exactly the same as in Samoa (pictured) before the disaster there, an expert says. Photo / Brett Phibbs

New Zealand is no more prepared for a major locally generated tsunami than Samoa, says an expert on tsunami, Dr Willem de Lange, of Waikato University.

He says there has been a historical reluctance in New Zealand to spend money on 24-hour staffing of a centre to monitor earthquakes and interpret the tsunami risk.

But the level of preparedness is "exactly the same as Samoa".

The Government is expected to release soon a report on the civil defence response in New Zealand to the September 29 tsunami, which struck Samoa's south coast, American Samoa and Tonga - after a magnitude 8 earthquake - and killed 183 people there, and after a quake struck Vanuatu.

According to Dr de Lange, there is a 10 to 12 per cent chance of a damaging tsunami hitting New Zealand during the course of a year.

But he said New Zealand's tsunami warning system focused on long-distance threats when the greatest danger is from an earthquake or submarine landslide close to the coast.

Scientists said after the 2004 Boxing Day tsunami which devastated coastal communities around the Indian Ocean that there was no monitoring in New Zealand for "local source" tsunami - waves which take less than an hour to travel to the coast - or "regional source" tsunami which take between one and three hours to arrive.

They warned that even with all the necessary information available, local warnings could take 100 minutes to compile and issue.

A further shortcoming was the lack of real-time sea-level data to detect and monitor the tsunami before it reached New Zealand coasts and to monitor its impact as it progressed along the country.

At the time, Civil Defence relied on Dr de Lange at Waikato University and Rob Bell at Niwa. GNS Science researchers told the Government that Japan is able to produce tsunami warnings within three minutes of an earthquake because it has developed 100 pre-computed models of distant-source tsunami, and 100,000 pre-computed models of local-source tsunami.

But Dr de Lange said the New Zealand warning systems could not cope with a tsunami from a close event, such as the big Fiordland earthquakes this year, to reach other parts of the coastline in 10 to 20 minutes.

In such events, a warning was needed within five minutes of a quake.

It was not really clear who should make the decision to evacuate, how much scientific advice should be taken before a decision was made, and whether confirmation of a tsunami was needed before a warning was issued.

Authorities were faced with triggering sirens every time there was a sizeable quake, Dr de Lange said. "We're in danger of crying wolf too often."


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