When Did Auckland's Volcanoes Last Erupt?
Auckland's most recent eruption created Rangitoto Island around 600 years ago, within the memory of Māori living nearby. It was the largest eruption the field has produced, and the field itself is still considered active.
When did Auckland's volcanoes last erupt?
The last eruption built Rangitoto Island, the symmetrical cone in the Hauraki Gulf, around 600 years ago. It was witnessed by Māori, with evidence of footprints preserved in ash on nearby Motutapu Island. Rangitoto was also the biggest single eruption in the field's history, producing roughly as much lava as all the other Auckland volcanoes combined.
How often does the field erupt?
Eruptions are infrequent on a human timescale. The field has produced around 53 volcanoes over roughly the last 200,000 years, so the average gap between eruptions is long, though they do not arrive on a neat schedule. Some periods saw clusters of activity and others long quiet. Rangitoto, the most recent, stands apart as both the youngest and by far the largest.
Could Auckland's volcanoes erupt again?
The field could, but the existing cones will not. Because Auckland is monogenetic, each volcano erupts only once, so Mount Eden and Rangitoto are done. A future eruption would build a brand new volcano at a new and unpredictable location, most likely in or near the existing field. This is why the field is classed as active rather than extinct.
Is the volcanic field monitored?
Yes. GeoNet runs seismographs and monitoring across the region, and Auckland has detailed emergency plans for volcanic activity. A new eruption would almost certainly be preceded by warning signs such as earthquakes and ground deformation in the days or weeks beforehand, giving time to respond. The point is not that an eruption is imminent, but that the system is watched.
See the field as it is today
Volcanic AKL maps every cone in the Auckland Volcanic Field with its history and geology, from the oldest hills to 600-year-old Rangitoto. Works offline.
Explore Volcanic AKLRelated: Why is Auckland built on volcanoes? and walking up Rangitoto.