The Auckland volcanic field is an area of monogenetic volcanoes covered by much of the metropolitan area of Auckland, New Zealand's largest city, located in the North Island. The field's 53 volcanoes (or thereabouts) have produced a diverse array of maars (explosion craters), tuff rings, scoria cones, and lava flows. Each volcano has erupted for just one period, lasting for weeks to several years, except for Rangitoto Island, which erupted repeatedly. The field is fuelled entirely by basaltic magma, unlike the explosive subduction-driven volcanism in the central North Island, such as at Mount Ruapehu and Lake Taupo. Currently dormant, the field is likely to erupt again within the next "hundreds to thousands of years" (based on past events), a very short timeframe in geologic terms.