Space Shuttle photo STS056-0093-0002. Looking southeast across Lake Rotorua, Rotorua Caldara, and the Okataina Volcanic Center.
The Rotorua caldera is circular in shape and about 10 miles (16 km) in diameter. Lake Rotorua is in the caldera. The caldera formed about 140,000 years ago as the Mamaku Ignimbrite erupted. The ignimbrite (welded and non-welde d pyroclastic flows) covers about 4,000 square km and is the youngest and most widespread ignimbrite in the Taupo Volcanic Zone. Rhyolite lava domes extruded after the caldera formed. The Whakarewarewa geothermal area contains numerous geysers, hot spri ngs, and boiling mud pots.
The Taupo Volcanic Zone (TVZ) is 12-48 miles (20-80 km) wide and extends from Ruapehu in the south to the Okataina Volcanic Center in the north and continues 120 miles (200 km) offshore. The zone is flanked by thick aprons of welded pyroclastic flows tha
t form shallow dipping plateaus. The Taupo Volcanic Zone has anomalously high heat flow and widespread hydrothermal activity. Volcanism began about 1 million years ago and has been calc-alkaline in character. Volcanic centers at Taupo can be divided int
o two types:
Major structures, lava types, and vent locations at the Rotorua and Okataina volcanic centers within the northern Taupo Volcanic Zone. Simplified from Cole (1990) after Cole (1986).
The Taupo Volcanic Zone. The top of the photo is to the northeast. Lake Taupo is near the bottom center, Hawke Bay is bottom right, Lake Rotorua is left of center, and Bay of Plenty is top left. Space Shuttle photo STS056-009 8-0075.
Simplified cross-section of the Rotorua caldera. From Houghton (1982).
On 26 January, a 2.5-3m hot pool (Spring 721) erupted sending blocks and mud 100 meters into the air. The eruption created a crater of ~10-12m in diameter. The incident was the largest hydrothermal eruption in Kuirau Park since 1966.
This information was summarized from Smithsonian Institution's Preliminary Notices of Volcanic Activity
Photos of the eruption can be viewed on New Zealand's Institute of Geological & Nuclear Sciences Limited Web site.
The Whakarewarewa geothermal area is adjacent to the New Zealand Maori Arts & Crafts Institute.
Cole, J.W., 1987, Structure, evolution, and economic importance of the Taupo Volcanic Zone, New Zealand: AusIMM Pacific Rim 87 Congress: p. 83-86.
Houghton, B.F., 1982, Geyserland: a guide to the volcanoes and geothermal areas of Rotorua, New Zealand Geol. Soc. Guidebook 4, 48 p.
Houghton, B., McPhie, J., and Simmons, S., 1994, Physical volcanology and modern geothermal systems; Field Guide 1 North Island, New Zealand: Masters of Economic Geology Course Work Manual 8, Centre for Ore Deposit and Exploration Studies (CODES), Univers ity of Tasmania.
Wilson, C.J.N., Rogan, A.M., Smith, I.E.N., Northey, D.J., Nairn, I.A., and Houghton, B.F., 1984, Caldera volcanoes of the taupo volcanic zone, New Zealand: Jour. Geophysiacl research, v. 89, p. 8463-8484.
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