The Auckland volcanic field is made up of 50 basalt volcanoes.
The volcanic field is a hot spot because it in the middle of a tectonic plate, not around the edge.
Some volcanoes in the volcanic field only erupt once which means it is a mono-genetic volcano. There are some other volcanoes such as Rangitoto that erupt more than once these are polygenetic volcanoes.
The Auckland Volacnic field is a 1/4 (quarter) of a million years old.
When One Tree hill erupted its lava flow reached the edge of Mount Smart which made Mount Smart erupt. The lava flow finally found its escape route into the Manukau River Valley. The result was a 4 metre drop in the water level.
Some day in the future I hope there will be no volcanic eruption.
I will hate to see one.