Our most recent volcano

Rangitoto was formed as a result of at least two eruptions between 600 and 700 years ago. It is the largest (and least altered) volcanic cone in the Auckland volcanic field. This is an area that has a concentration of lava flows, from which magma bubbles sporadically surface, creating the scoria cones.

Rangitoto is described as an intra-plate or hot spot volcano. This means that it develops away from the edge of a plate, and its formation is not a result of subduction.

Residents of Auckland can gain some reassurance from the description of the Auckland field as monogenetic, which means that each volcano erupts only once. However, because the field is still active, another magma bubble may form and rise to the surface resulting in another volcanic cone. Where and when is unpredictable.

They tell us, though, that there will be another eruption at some time. Perhaps another island will be formed in the Hauraki Gulf, or another basin in the city itself (A number of the past eruptions produced craters without a cone.).