World Library  
Flag as Inappropriate
Email this Article
 

Oruanui eruption

The Oruanui eruption of New Zealand's Taupo Volcano, the world's largest known eruption in the past 70,000 years, had a Volcanic Explosivity Index of 8. It occurred around 26,500 years ago in the Late Pleistocene and generated approximately 430 km3 (100 cu mi) of pyroclastic fall deposits, 320 km3 (77 cu mi) of pyroclastic density current (PDC) deposits (mostly ignimbrite) and 420 km3 (100 cu mi) of primary intracaldera material, equivalent to 530 km3 (130 cu mi) of magma. The eruption is divided into 10 phases on the basis of nine mappable fall units and a tenth, poorly preserved but volumetrically dominant fall unit.

Modern Lake Taupo partly fills the caldera generated during this eruption; a 140 km2 (54 sq mi) structural collapse area is concealed beneath the lake, while the lake outline reflects coeval peripheral and volcano-tectonic collapse. Early eruption phases saw shifting vent positions; development of the caldera to its maximum extent (indicated by lithic lag breccias) occurred during phase 10.

The Oruanui eruption shows many unusual features: its episodic nature, wide range of depositional conditions in fall deposits of very wide dispersal, and complex interplay of falls and pyroclastic flows.

Tephra from the eruption covered much of the central North Island with ignimbrite up to 200 metres (660 ft) deep. Ashfall affected most of New Zealand, with even an 18 cm (7 in) ash layer deposited on the Chatham Islands, 1,000 km (620 mi) away. Later erosion and sedimentation had long-lasting effects on the landscape, and caused the Waikato River to shift from the Hauraki Plains to its current course through the Waikato to the Tasman Sea.

See also

References

  • Wilson, Colin J. N. (2001). "The 26.5 ka Oruanui eruption, New Zealand: an introduction and overview". Journal of Volcanology and Geothermal Research 112: 133–174.  
  • Manville, Vern & Wilson, Colin J. N. (2004). "The 26.5 ka Oruanui eruption, New Zealand: a review of the roles of volcanism and climate in the post-eruptive sedimentary response". New Zealand Journal of Geology & Geophysics 47 (3): 525–547.  
  • Wilson, Colin J. N. et al. (2006). "The 26.5 ka Oruanui Eruption, Taupo Volcano, New Zealand: Development, Characteristics and Evacuation of a Large Rhyolitic Magma Body". Journal of Petrology 47 (1): 35–69.  
  • Richard Smith, David J. Lowe and Ian Wright. 'Volcanoes - Lake Taupo', Te Ara - the Encyclopedia of New Zealand, updated 16-Apr-2007.

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.