Reporoa Caldera

The Reporoa Caldera is a 10 km by 15 km caldera in New Zealand's Taupō Volcanic Zone. It formed some 230,000 years ago,[1] in a large eruption that deposited approximately 100 km3 of tephra, forming the Kaingaroa Ignimbrite layer.[2] The ignimbrite sheet extends up to 15 km (9.3 mi) to the east.[3] It contains three rhyolitic lava domes (Deer Hill, Kairuru and Pukekahu) and is associated with three geothermal fields. These are the active Reporoa geothermal field in the caldera, the Waiotapu geothermal area north of the caldera rim, and the Broadlands thermal area to the south. The Waikato River runs through the southern half of the caldera.

Reporoa Caldera
Highest point
Elevation592 m (1,942 ft)
Coordinates38°25′00″S 176°20′00″E
Dimensions
Length15 km (9.3 mi)
Width10 km (6.2 mi)
Geography
LocationTaupō Volcanic Zone, New Zealand
Geology
Age of rock
Mountain typeCaldera
Last eruption1180 (?), 2005 hydrothermal
Okataina Volcanic Centre relationships to other nearby volcanic and tectonic structures
The Reporoa Caldera is to the east of the Paeroa Fault and south of the Ngapouri-Rotomahana Fault. It is accordingly south of the Okataina Volcanic Centre (approximate thick white border) and occupies a low land area between this and Lake Taupō

In April 2005, a large hydrothermal explosion occurred near a cow paddock within the caldera, destroying some trees, temporarily blocking a nearby stream and creating a 50-metre crater at 38°32′02″S 176°10′19″E.[4] A similar explosion happened in the area in 1948, and smaller explosions have happened in the years between.[5][4]

See also

References
  • "Reporoa". Global Volcanism Program. Smithsonian Institution.
  1. S. W. Beresford; J. W. Cole (2000). "Kaingaroa Ignimbrite, Taupo Volcanic Zone, New Zealand: evidence for asymmetric caldera subsidence of the Reporoa Caldera". New Zealand Journal of Geology & Geophysics. 43 (3): 471–481. doi:10.1080/00288306.2000.9514903.
  2. I. A. Nairn; C. P. Wood; R. A. Bailey (December 1994). "The Reporoa Caldera, Taupo Volcanic Zone: source of the Kaingaroa Ignimbrites". Bulletin of Volcanology. 56 (6): 529–537. Bibcode:1994BVol...56..529N. doi:10.1007/BF00302833. S2CID 128947835.
  3. Spinks, Karl D. (2005). "Rift Architecture and Caldera Volcanism in the Taupo Volcanic Zone, New Zealand".
  4. Simpson, Mark P.; Rosenberg, Michael D.; Rae, Andrew J.; Bignall, Greg; Mountain, Bruce W.; Graham, Duncan; Chappell, Debra (2014). "Insight into the 2005 hydrothermal eruption at South Orakonui, Ngatamariki Geothermal Field, New Zealand from calcite microthermometry". Retrieved 16 October 2022.
  5. Geothermal eruption in New Zealand paddock leaves big crater, The Star, 20 April 2005.
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