The Bay of Plenty region contains one of New Zealand's most important areas of potential volcanic activity, the Okataina Volcanic Centre. Immediately southwest of the region lies the Taupo Volcanic Centre, which links with the volcanic cones of Ruapehu and Tongariro.
The complete volcanic zone running from Mt Ruapehu to White Island, 50 kilometres off the region's coastline, is called the Taupo Volcanic Zone (TVZ). The TVZ runs straight through the centre of the Bay of Plenty region, taking in the major urban areas of Rotorua and Kawerau, and fringing Whakatane township.
Volcanic eruptions from within or outside the region, and earthquakes mainly from within the Bay of Plenty region, are likely to affect the population within any one person's lifetime.
A major historic eruption from the Okataina Volcanic Centre was Mt Tarawera, 1886, killing over 150 of the residents of that time. The ashfall from that eruption can still be found in the regional soil profiles today. Soil profiles also show that much larger eruptions have happened many times over the last 20 000 years.
Previous eruptions are known to have been much greater in both volume and duration. The eruption preceding the 1886 eruption, about 1305 AD, lasted for at least four years and was approximately four times as large. On average, major eruptions from the Okataina Volcanic Centre occur about every 2000 years.