Aucklanders should get ready for an eruption - expert

Auckland households are being urged to have conversations about what they will do if there is a volcanic eruption.

Prime documentary series Beneath New Zealand on Sunday night will feature the Civil Defence emergency management team responding to a simulated event

Auckland Council principal science advisor Angela Doherty says Aucklanders forget the city has grown up around volcanoes.

"A volcanic eruption is always a possibility, and it's something that we do always have to keep in the back of our minds, and start having those conversations, making plans with our whanau and friends about what we could do."

Research by Kiwi volcanologists last year found there could be as little as five days between the first detection of activity beneath the city and a devastating blast.

Auckland's volcanic field can be seen on the hazard viewer on the Emergency Management website.

Auckland's volcanoes seen on the council's online hazard viewer.
Auckland's volcanoes seen on the council's online hazard viewer. Photo credit: Auckland Council

Dr Doherty says it cannot be known exactly where an eruption would happen, but the volcanic field is mainly central.

"When the eruption is imminent and when the activity is building, scientists can get a better idea about where it's likely, then we can make plans about what we might need to do in that situation and what kind of impacts Auckland might face."

She's urging people start to prepare for such an emergency - and in the event of a disaster, follow the advice of emergency services.

"Don't evacuate unless you're asked to, make sure the roads are clear for the people who do need to evacuate - there will be ash, there will be smoke."

Auckland has about 50 volcanoes. The most recent eruption was Rangitoto, about 550 years ago.

Evacuating an area of central Auckland with a 5km radius - about 78 square kilometres - would require moving up to 435,000 people. Canterbury University research found a two-month eruption near Mangere Bridge would destroy anything up to two-and-a-half kilometres away, leave transport networks crippled and a third of the population as refugees.

It could also generate a 2m-high tsunami around the harbour.

"What we do know is it is certainly a case of 'when' rather than 'if', and that the location of the eruption will be within the current bounds of the volcanic field, which will almost certainly impact Auckland," Victoria University volcanic geochemist Jenni Hopkins told Newshub earlier this year.

Newshub.