North Island surface volcanism
Much of the volcanic activity in the northern portions of the North Island of New Zealand is recent in geological terms and has taken place over the last 30 million years. This is primarily due to the North Island's position on the boundary between the Indo-Australian and Pacific plates, a part of the Pacific Ring of Fire, and particularly the subduction of the Pacific plate under the Indo-Australian plate.
Source: Wikipedia — North Island surface volcanism (CC BY-SA 4.0)