The Auckland Volcanic Field directly underlies the largest city of New Zealand and consists of more than 50 basaltic cones, maars and lava flows. It covers an elliptical area of 29 (N-S) x 16.5 (E-W) km and has been active for the past 140,000 years, during which is has produced about 7 cubic km of mostly basaltic lava. The last eruption was as recently as about 600 years ago when the cone of Rangitoto Island was formed. About 20 eruptions have occurred during the past 20,000 years, suggesting an average recurrence interval of approx. 1000 years. Since eruptions could (and likely will) occur again in the future, it is a considerable hazard to Auckland city, especially since the time between first signs (seismic swarms, ground movements, gas emissions) to an eruption could be relatively short (weeks to months).