A major research project is under way to improve the understanding of the vulnerability of the Auckland region to volcanic eruptions.
The city is built on a volcanic field in which 50 volcanoes have erupted over the past 250,000 years.
The volcanoes are now considered extinct but knowledge of how future eruptions might occur is incomplete.
The seven-year exercise aims to better define Auckland's volcanic risk using the latest geological techniques and sophisticated computer modelling.
The information provided from the $5 million project, called Devora (Determining volcanic risk in Auckland) will help prepare the city for any future volcanic eruption by enabling better decision-making to protect assets and reduce casualties.
The Government-owned research and consultancy company GNS Science and the Institute of Earth Science and Engineering at Auckland University are jointly leading the project in collaboration with public and private sector organisations.
Jan Lindsay, joint project leader, said it would be a step forward in improving the understanding of the risk to Auckland, and Aucklanders, from volcanoes.
"It's not a matter of if, but when, and the more we know about volcanoes and the impact an eruption would have on our city, the better prepared Auckland can be."
Dr Lindsay said there were three main strands to the research - physical models of how the volcanoes worked, risk and hazards from the volcanoes, and the social and economic impacts.
The project would improve knowledge of the history of the Auckland volcanoes and the effects they have had on what is now Auckland City.
A future volcano might erupt anywhere within Auckland with effects such as lava flows, hot ash and gas avalanches, fire fountains and ash fall.
Auckland was also at risk from ash fall from distant eruptions at volcanoes in the central North Island, and Devora would improve understanding of that threat as well.
Alex Malahoff, chief executive of GNS Science, said the collaboration would provide an unprecedented amount of information on the volcanic risk in the region.
"It is important to understand how the volcanic field might erupt in the future, so Auckland can continue to develop as a major economic hub in New Zealand and the Southwest Pacific."
Dr Malahoff said the project was designed so the information could be taken up readily and used in civil engineering, infrastructure planning, emergency management and the insurance industry.
David Middleton, chief executive of the Earthquake Commission, said the research was needed because not enough was known about the risk of volcanic eruption in the Auckland region.
"It is important that conventional wisdom is not allowed to crowd out scientific advances. The better our understanding of the hazards we face, the better equipped we can become to deal with them."
This work was based on the success of the "It's Our Fault" project in Wellington where the risk of earthquake in the region was assessed through a collaboration of industry, regional government and science institutions.
THE FULL PICTURE
* Auckland is built on a volcanic field.
* 50 volcanoes have erupted over the past 250,000 years.
* Each volcano erupted for a few months or years and then became extinct.
* Knowledge of when each volcano erupted, and how future eruptions might occur is incomplete.