- Auckland volcanic field
The Auckland volcanic field is a generally
monogenetic volcanic fieldin the North Islandof New Zealand. Basaltic in nature, it underlies much of the metropolitan areaof Auckland. The field's many vents have produced a diverse array of explosion craters, scoriacones, and lavaflows. Currently dormant, the field is likely to erupt again within the next "hundreds to thousands of years" (based on past events), a very short timeframe in geologic terms.Beca Carter Hollings & Ferner (2002). " [http://www.arc.govt.nz/albany/fms/main/Documents/Council/Civil%20defence%20emergency%20management/Publications%20&%20factsheets/Auckland%20Volcanic%20Plan%20(VCP).pdf Contingency Plan for the Auckland Volcanic Field] ", Auckland Regional CouncilTechnical Publication 165. Accessed 2008-05-12.]
The first vents erupted at the Domain, Albert Park and St Heliers between 60,000 and 140,000 years ago. Since then approximately 50 vents have erupted. Each eruptive vent has generally only had a geologically short period of activity. One exception is
Panmure Basin, where drilling has discovered a younger scoria cone buried under sediment within the larger and much older crater. [" [http://www.nzherald.co.nz/section/1/story.cfm?c_id=1&objectid=10493865 New Auckland volcano discovered] " - NZPAvia " The New Zealand Herald", 22 February 2008. Accessed 22 February 2008.]
The most recent eruption (about 600 years ago and within historical memory of the local
Māoriiwis) was of Rangitoto, an island shield volcanojust east of the city, erupting 2.3 cubic kilometres of lava. The eruptions have tended to become bigger over time, with Rangitoto making up almost 60% of the field's entire volume of erupted material. All of the volcanoes are relatively small, most being less than 150 meters in height.
The field has produced voluminous
lava flows, which cover much of the Auckland isthmus. One of the longest runs from Three Kings northward, almost crossing the Waitemata Harbourto form Meola Reef. More than 50 lava tubes and other lava caves have been discovered, including the 290 metre long Wiri Lava Cave. [" [http://www.historic.org.nz/magazinefeatures/2006Winter/2006_Winter_CaveNewWorld%20.htm Cave New World] " - David Lomas, " Heritage New Zealand", Winter 2006. Accessed 2007-05-04.]
Several of the volcanic cones were occupied by substantial
Māoripa before European settlement, and many terraces and other archeological remnants are still visible. Many of the cones have been levelled or strongly altered - in small part due to the historical Māoriuse, but mostly through relatively recent quarrying of construction materials (especially scoria). However several of the remaining volcanoes are now preserved as landmarks and parks. The cones are also protected by a 1915 law, the Reserves and Other Lands Disposal and Public Bodies Empowering Act 1915, which was passed due to early concern that the distinctive landscape was being eroded, especially by quarrying. While often ignored until the late 20th century, it has amongst other things minimised severe changes to Mount Roskill proposed by Transit New Zealandfor the Southwestern Motorway."The volcanic hills are being destroyed..." - "City of Fire", insert magazine in the " The New Zealand Herald", Friday 15 February 2008]
In March 2007, New Zealand submitted the volcanic field, with several specifically named features, as a
World Heritage Sitecandidate based on its unique combination of natural and cultural features. [http://whc.unesco.org/pg_friendly_print.cfm?cid=326&id=5120& Auckland Volcanic Fields submission] (from the UNESCOWorld Heritage Centre, 2007-03-30. Accessed 2007-05-04)] At that time, only 2% of more than 800 World Heritage Sites worldwide were in this "mixed" category.
Since the field is not extinct, new volcanic events may occur at any time, though the usual period between events averages between hundreds and thousands of years. However, the effects of such an event, especially a full-scale eruption, would be substantial - ranging from
earthquakes, lava bombs, ash falls, venting volcanic gasto lava flows. These effects might continue for several months and cause substantial destruction and disruption. These might range from burial of substantial tracts of residential or commercial property to mid-to-long-term closures of major parts of the country's infrastructure, such as the Port of Auckland, the State Highway network or the Auckland International Airport.
Various operative structures, plans and systems have been set up to prepare responses to renewed volcanic activity within the urban areas, mainly coordinated in the 'Auckland Volcanic Field Contingency Plan' of the
Auckland Regional Council, which provides a framework for interaction of civil defenseand emergency servicesduring an eruption. Auckland also has a Seismic Monitoring Network comprising six seismometers (including one 250 m deep at Riverhead) and three repeaters within the Auckland Region) that will pick up the small tremors likely preceding any such volcanic activity. [NZPA, [http://www.nzherald.co.nz/section/1/story.cfm?c_id=1&objectid=10509437 New recorder boosts earthquake, volcano warnings] , " The New Zealand Herald", 2008-05-11. Accessed 2008-05-12.] These tremors are likely to give some hours to some days of warning about an impending eruption and its approximate location."When the earth starts to shake" - "City of Fire", insert magazine in the " The New Zealand Herald", Friday 15 February 2008]
List of volcanoes
The volcanoes within the field include:
*Browns Island ("Motukorea")
*Mount Albert ("Owairaka")
*Mount Hobson ("Remuwera" [ [http://www.aucklandcity.govt.nz/council/documents/managementplans/mthobson/section4.asp History] , Mt Hobson Remuwera management plan, Auckland City Council, 13 December 2000. ISBN 0908834500.] )
*Mount Saint John
*Mount Wellington ("Maungarei")
*North Head ("Maungauika")
*One Tree Hill ("Maungakiekie")
*Pukekawa (Auckland Domain volcano)
Robertson Hill(Sturges Park)
Saint Heliers(Glover Park) - see Achilles Point
Tank Farm(also known as 'Tuff Crater Lagoon')
Volcanism in New Zealand
*"Lava and Strata: A guide to the volcanoes and rock formations of Auckland" - Homer, Lloyd Homer; Moore, Phil & Kermode, Les; Landscape Publications and the Institute of Geological and Nuclear Sciences, 2000. ISBN 0-908800-02-9.
*"Probabilistic assessment of future vent locations and eruption styles for the Auckland Volcanic Field, New Zealand" - Magill, Christina R; McAneney, K.J.; Proceedings of the
International Association for Mathematical Geology2003, Portsmouth, UK, September 7-12, 2003.
* [http://dx.doi.org/10.1007/s00445-004-0374-6 Volcanic risk ranking for Auckland, New Zealand. I: Methodology and hazard investigation] - Magill, Christina R.; Blong, Russell; "
Bulletin of Volcanology", Volume 67, Issue 4, April 2005, Pages 331 - 339, DOI 10.1007/s00445-004-0374-6, accessed 2006-07-14.
*"City of Volcanoes: A geology of Auckland" - Searle, Ernest J.; revised by Mayhill, R.D.; Longman Paul, 1981. First published 1964. ISBN 0-582-71784-1.
*" [http://www.rsnz.org/publish/nzjgg/1996/119.php Facies analysis of pyroclastic deposits within basaltic tuff-rings of the Auckland volcanic field, New Zealand (abstract)] " - Sharon R. Allen, Vivienne F. Bryner, Ian E. M. Smith, Peter F. Ballance, "
New Zealand Journal of Geology and Geophysics", 1996, Vol. 39: 309-327.
* [http://www.gns.cri.nz/what/earthact/volcanoes/nzvolcanoes/aucklandprint.htm NZ Institute of Geological and Nuclear Sciences Auckland Volcano page]
* [http://www.arc.govt.nz/environment/volcanoes-of-auckland/volcanoes-of-auckland_home.cfm Auckland Regional Council - The Volcanoes of Auckland]
* [http://geology.auckland.ac.nz/rocks_minerals/auckland/index.html University of Auckland's Geology of Auckland page] (with interactive maps, requiring Apple
Wikimedia Foundation. 2010.
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