KEY POINTS:
Warning systems about possible tsunami heading to New Zealand are not consistent among the country's coastal communities, a natural disasters conference heard yesterday.
Mike O'Leary, operations manager for the Ministry of Civil Defence and Emergency Management, told the conference that getting warning information down to community level was patchy.
Mr O'Leary was specifically referring to the civil defence emergency management groups which were responsible for disseminating national warnings to local communities.
"That is our greatest vulnerability in New Zealand. There is a very patchy capability to do that across the country and in some cases it's not even identified."
Mr O'Leary said there were few proven and operating public alert systems such as sirens.
But he was personally not a great fan of the use of sirens in warning systems as their efficacy was debatable, there were problems with their maintenance and they could create a false impression of safety and security.
John Hamilton, the ministry's director, agreed systems were patchy and said a national working group had been set up to get some standardisation.
Mr Hamilton added, however, that while standardisation was ideal, there were some limits to that given variations in coastal sites, such as areas which had no cellphone transmission.
He said at present if New Zealanders contacted their local councils to find out what the warnings were for their areas they would probably be greeted by a "stunned silence" because systems were not properly developed.
Mr Hamilton hoped a national system would be sorted out so someone lying on a beach at Mission Bay, in Auckland, or at Evans Bay in Wellington, would immediately recognise a tsunami warning and take action.
Mr O'Leary also told the conference that tsunami warnings currently provided arrival times but did not detail the expected impact.
Limitations of the Pacific tsunami warning system included simplistic modelling and the failure to take into account the effect of land masses like Australia, which could be in the path of a tsunami heading here.
Mr O'Leary said New Zealand could become a regional warning center for the southwest Pacific.
Rana Solomon, emergency response co-ordinator Chatham Islands, said the risk of a tsunami was the number one environmental hazard in the Chathams, located 850km east of New Zealand.
A major tsunami could have a devastating effect because the main settlement was located on a low-lying main island with a large lagoon in the middle.
Miss Solomon said the island had its own systems but the population of 700 was often bolstered by tourists who might not recognise or respond to the local warning system.
In 1868, a six-metre tsunami triggered by a magnitude 9 earthquake offshore from the Peru-Chile border washed into the huts of a Maori village on the northwest coast of the main island. People rushed to higher ground before a second and bigger wave arrived 10 minutes later, destroying the village and drowning one person.
In 1924, six-metre waves from Chile pounded the Chatham Islands and in 1960 a tsunami from another huge earthquake in Chile drove in a 3-4m wave.
Seismologists told the conference that more research and information was needed on defining tsunami risks, including where land would be inundated, the preparation of evacuation maps, and modelling of credible volcano and landslide sources.
Dr Warwick Smith said not a lot was known about how large the tsunami-triggering earthquakes would be, their frequency, how big the waves generated would be, when they would hit land or the likely damage that would be caused.
Dr Smith said distant source tsunami generated from South America would probably hit New Zealand if they emanated from northern Peru, while those from the southern part of South America would head in the direction of Hawaii.
Tsunami had the potential for a far greater number of fatalities than earthquakes, he said.
