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Okataina Volcano, New Zealand
This large fissure system produced during a major explosive eruption at Tarawera in 1886 is one of the most dramatic features of the massive Okataina Volcanic Centre.
Okataina is surrounded by extensive ignimbrite and pyroclastic sheets produced during caldera-forming eruptions.
The subparallel NE-SW-trending Haroharo and Tarawera complexes consist of rhyolitic lava domes and associated lava flows that formed between about 15,000 and 800 years ago and impounded lakes against the margins of the Okataina ring structure.
The massive, dominantly rhyolitic Okataina Volcanic Centre is surrounded by extensive ignimbrite and pyroclastic sheets produced during multiple caldera-forming eruptions.
Numerous lava domes and craters erupted from two subparallel NE-SW-trending vent lineations form the Haroharo and Tarawera volcanic complexes.
Lava domes of the Haroharo complex, at the northern end of the Okataina Volcanic Centre, occupy part of the 16 x 26 km Pleistocene Haroharo caldera, which formed incrementally between 300,000 and 50,000 years before present (BP).
The oldest exposed rocks on the caldera floor are about 22,000 years old.
The Tarawera complex at the southern end of Okataina consists of 11 rhyolitic lava domes and associated lava flows.
The oldest domes were formed as late as about 15,000 years BP, and the youngest were formed in the Kaharoa eruption about 800 years BP.
The NE-SW Tarawera vent lineation extends from the two dacitic cones of Maungaongaonga and Mangakakaramea on the SW to Mount Edgecumbe on the NE.
Construction of the Haroharo and Tarawera complexes impounded lakes Rotoiti, Totoehu, Okataina, and Tarawera against the outer margins of the Okataina ring structure.
A major hydrothermal area is located at Waimangu; the world-renowned Pink and White Terrace siliceous sinter deposits were destroyed during the major basaltic explosive eruption of 1886.
PHOTO SOURCE: Richard Waitt, 1986 (U.S. Geological Survey), courtesy of the Global Volcanism Program, Smithsonian National Museum of Natural History, used with permission.
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