Mayor Island is an infrequently active bush covered volcano sitting quietly in the Bay of Plenty, offshore from Waihi. It is about 4 km in diameter and is dominated by a caldera (collapse crater).
Since activity began, about 130 000 years ago there have been atleast 52 eruptions –a minimum of once every 3000 years. Exact timing of the most recent eruptions is unclear although some lava flows are thought to be about 500 to 1000 years old.
Volcanologists find Mayor Island interesting because it has a very diverse history of eruption styles including fire fountaining, lava domes and very explosive eruptions from contact with water.
GNS Science is monitoring Mayor Island with a seismograph to indicate volcanic earthquake activity.