Researchers have found at least half of all the volcanic eruptions in Auckland have occurred in the last 60,000 years, with the most recent eruption only 500 years ago.
Two new studies have revealed Auckland's temperamental and surprisingly young volcanic past is making it hard for scientists and authorities to pinpoint when the city of sails may be struck by another blow, but don't believe they will see an eruption in this lifetime.
"What we now know [based on the new research] is that some eruptions flare-up over what is, geologically speaking, a short period of time," GNS scientist Dr Graham Leonard says.
"For example, there can be 6 to10 volcanoes erupting within a 4000-year timeframe.
"On the other hand, the volcanic field has also gone quiet for up to 10,000 years in the last 60,000 years, which is quite a long gap."
At least 53 eruptions have occurred in Auckland's volcanic field lifetime, estimated to be about 200,000 years old.
The young volcanic field is forecast to erupt again but Victoria University's Dr Jenni Hopkins, a volcanic geochemist, says it is difficult to tell when the next eruption could happen.
"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," she says.
GNS Science runs the GeoNet network that monitors volcanic activity in New Zealand and advises authorities about what signs there are leading to any possible eruptions.
The studies have been published in the Journal of Volcanology and Geothermal Research and in the Bulletin of Volcanology by a team of researchers from the Determining Volcanic Risk in Auckland.