Location and extent of the Auckland volcanic field. Clicking on the map enlarges it, and enables panning and mouseover of volcano name/wikilink. Please also see for age and geographical relationships to other North Island surface volcanism
The Auckland volcanic field is an area of monogenetic volcanoes covered by much of the metropolitan area of Auckland, New Zealand's largest city, located in the North Island. The approximately 53 volcanoes[2] in the field have produced a diverse array of maars (explosion craters), tuff rings, scoria cones, and lava flows. With the exception of Rangitoto, no volcano has erupted more than once,[3][4] but the other eruptions lasted for various periods ranging from a few weeks to several years.[5] Rangitoto erupted several times[4] and recently twice; in an eruption that occurred about 600 years ago, followed by a second eruption approximately 50 years later.[6] The field is fuelled entirely by basalticmagma, unlike the explosive subduction-driven volcanism in the central North Island, such as at Mount Ruapehu and Lake Taupō.[7]
The first vent erupted at Pupuke 193,200 ± 2,800 years ago.[1] The most recent eruption (about 600 years ago[8] and within historical memory of the local Māori) was of Rangitoto, an island shield volcano just east of the city, erupting 0.7 cubic kilometres of lava. The last volcano to erupt was much bigger than all others, with Rangitoto making up 41 per cent of the field's entire volume of erupted material[9] with characteristics as to slope and symmetry around the eruptive vents seen in basaltic shield volcanoes as might be expected in a volcano, that may have buried other volcanoes, and now known to have a 1000-year odd eruptive history.[4][3] The field's other volcanoes are relatively small, with most less than 150 metres (490ft) in height.
Lake Pupuke, on the North Shore near Takapuna, is a volcanic explosion crater. A few similar craters such as Ōrākei Basin are open to the sea.
The field has produced voluminous lava flows that cover much of the Auckland isthmus. One of the longest runs from Mt Saint John northward, almost crossing the Waitematā Harbour to form Meola Reef.[10] More than 50 lava tubes and other lava caves have been discovered, including the 290-metre (950ft)-long Wiri Lava Cave.[11] There can be an association with lava caves and the formation of rootless cones due to their mechanism of formation and a rootless cone was suggested to exist at Wiri being Matukutūreia.[12] This may not be quite the case even though at least one steam only driven eruption occurred close to Matukutūreia.[13] The second-longest individual cave in the Auckland field, some 270 metres (890ft) in total length, is the Cave of a Thousand Press-ups to the east of Maungakiekie/One Tree Hill.[14] Two impressive depressions caused by lava cave collapses are the Puka Street Grotto and the nearby Hochstetter Pond, also known as Grotto Street Pond, in Onehunga.[15][16]
For most of the 200,000 years that the field has been erupting, the planet has been in glacial periods (ice ages) where sea levels were much lower due to water being locked up as ice, and the Waitemata and Manukau Harbours were dry land. All the volcanoes probably erupted on land except for Rangitoto, which erupted during the current interglacial (warmer) period.[17]
Tectonic relationships
Map of faults and Quaternary volcanoes in the Auckland region. To show well the volcanoes in relation to fault lines you have to click on the map to enlarge and then zoom and pan. This also enables mouse over of the volcano and fault names. Definite active faults are shown in red. Well characterised inactive fault segments are in dark grey and other faults are shown in grey. A number of faults characterised by sea floor studies off the west coast of North Island are not shown. The type of volcanic eruption (some are composite) is indicated by basalt shield type eruption (black), scoria cone (red), or phreatomagmatic eruptions tuff ring (red-brown) and maar (purple). Volcanoes from both the Auckland volcanic field and South Auckland volcanic field are displayed. Miocene volcanoes are not shown.
The Auckland region lies within the Australian Plate, about 400 kilometres (250mi) west of its plate boundary with the Pacific Plate.[18] The volcanoes are located south of a geological region called the Northland Allochthon, and with the northern volcanoes located over early Miocene sedimentary deposits of the Waitematā Group of rocks and the southern volcanoes over post Miocene sediments.[18] A large proportion of the volcanoes in the field, particularly those with cone structures, lie within 500 metres (1,600ft) of inferred or known faults, with the qualification that these are inactive historic faults and unlike in many other volcanic fields it is rare for volcanoes to be actually on the fault line.[19] The structure of these Auckland regional faults and the resulting fault blocks is complex but like the volcanic field their locations can be postulated to be related to gravitational variations and where the Stokes Magnetic Anomaly passes through this section of the North Island.[18] The field is part of the Auckland Volcanic Province which comprises four volcanic fields with intra-plate basaltic volcanism starting in the south, at Okete, near Raglan in late Pliocene times (2.7-1.8 Ma).[20] Activity has since moved north through the Ngatutura, South Auckland and Auckland fields since then.[21]
Tāmaki Māori myths describe the creation of the volcanic field as a creation of Mataaho (the guardian of the earth's secrets) and his brother Rūaumoko (the god of earthquakes and volcanoes), made as punishment against a tribe of patupaiarehe, supernatural beings living in the Waitākere Ranges, who used deadly magic from the earth to defeat a war party of patupaiarehe from the Hunua Ranges.[22][23] In some traditions, the fire goddess Mahuika creates the volcanic field as a way to warm Mataaho, after his wife leaves and takes his clothing.[24][25] Because of their close association to Mataaho, the volcanic features can be collectively referred to as Nga Maunga a Mataaho ("The Mountains of Mataaho"),[22] or Ngā Huinga-a-Mataaho ("the gathered volcanoes of Mataaho").[25] Many of the volcanic features of Māngere can be referred to as Nga Tapuwae a Mataoho ("The Sacred Footprints of Mataoho"), including Māngere Lagoon, Waitomokia, Crater Hill, Kohuora, Pukaki Lagoon and Robertson Hill.[24][26] Many of the Māori language names of volcanic features in the field refer to Mataaho by name, including Te Pane o Mataaho (Māngere Mountain), Te Tapuwae a Mataoho (Robertson Hill) and Te Kapua Kai o Mataoho (the crater of Maungawhau / Mount Eden).
Usage
Many of the maunga (mountains) were occupied by substantial Māoripā (fortifications) before Pākehā settlement, and many terraces and other archeological remnants are still visible.[27] Many of the cones have been levelled or strongly altered, in small part due to the historical Māori use, but mostly through relatively recent quarrying of construction materials (especially scoria). However many of the remaining volcanoes are now preserved as landmarks and parks.[8]
The warmer northern sides of the mountains were also popular among early Pākehā settlers for housing.[27] In the 1880s, Takarunga / Mount Victoria and Maungauika / North Head were developed as military installations due to fears of a Russian invasion.[27] 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 Zealand for the Southwestern Motorway.[28]
In March 2007, New Zealand submitted the volcanic field, with several specifically named features, as a World Heritage Site candidate based on its unique combination of natural and cultural features.[8] At that time, only 2 per cent of more than 800 World Heritage Sites worldwide were in this "mixed" category.
In the 2014 Treaty of Waitangi settlement between the Crown and the Ngā Mana Whenua o Tāmaki Makaurau collective of 13 Auckland iwi and hapu (also known as the Tāmaki Collective), ownership of the 14 Tūpuna Maunga (ancestral mountains) of Tāmaki Makaurau / Auckland, was vested to the collective. The legislation specified that the land be held in trust "for the common benefit of Ngā Mana Whenua o Tāmaki Makaurau and the other people of Auckland". The Tūpuna Maunga o Tāmaki Makaurau Authority or Tūpuna Maunga Authority (TMA) is the co-governance organisation established to administer the 14 Tūpuna Maunga. Auckland Council manages the Tūpuna Maunga under the direction of the TMA.[27][29][30]
Dangers
Since the field is not extinct, new volcanic events may occur at any time, though the usual period between events is, on average, somewhere between hundreds to thousands of years. There has been at least one eruption in every 2,500 years over the last 50,000 years.[20] However, the effects of such an event—especially a full-scale eruption—would be substantial, ranging from pyroclastic surges to earthquakes,[31]lava bombs, ash falls, and the venting volcanic gas, as well as lava flows. These effects might continue for several months, potentially causing substantial destruction and disruption, ranging from the burial of substantial tracts of residential or commercial property, to the 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 Airport.[32] It is possible that several volcanoes could erupt simultaneously. There is strong evidence that eight erupted within a span of 3000 years or so, between 31,000 and 28,000 years ago.
Most eruptive events in the field have been small volume, very constrained in time, typically involving less than 0.005km3 (0.0012cumi) of magma making its way to the surface.[20] However the same amount of magma can have an order of magnitude different impact. An underwater eruption which is more likely to be explosive resulted in the formation of the 0.7km (0.43mi) wide Ōrākei crater that destroyed an area of 3km3 (0.72cumi) by crater formation and base surge impact. This contrasts with the about 0.5km (0.31mi) diameter cone produced by the same amount of upwelling magma that might be expected to destroy an area of 0.3km3 (0.072cumi) if there is no ground water interaction.[20] Modelling has suggested that the next eruption in the volcanic field is likely to be associated with water and in the area extending from the central city to its north and northeast suburbs surrounding and including the Waitemata Harbour.[33] Within New Zealand the volcanic hazard of the field is graded below that of Taupo Volcanic Zone volcano's but is likely to be perceived by the population affected as a greater potential nuisance if it occurs[34]
Various operative structures, plans and systems have been set up to prepare responses to volcanic activity within the urban areas, mainly coordinated in the Auckland Volcanic Field Contingency Plan[32] of the Auckland Regional Council, which provides a framework for interaction of civil defence and emergency services during an eruption. Auckland also has a seismic monitoring network comprising six seismometers—including one 250 metres (820ft) deep at Riverhead—and three repeaters within the region that will detect the small tremors likely to precede any volcanic activity.[35] This is likely to give between a few hours and several days' warning of an impending eruption, and its approximate location.[31]
Auckland War Memorial Museum, itself built on the crater rim of Pukekawa, has an exhibition on the field, including the "Puia Street multi-sensory visitor experience", which simulates a grandstand view of an eruption in Auckland.[36]
Whakamuhu / St Heliers Volcano, 2009The Glover Park sports ground at lower right of this photo is situated within the Whakamuhu tuff ring. Over the water in the distance on the right is the scoria cone of Maungauika / North Head and in the left middle is the tuff crater filled in by the sea of Ōrākei Basin. Beyond Ōrākei Basin in the middle distance are several vegetation covered scoria cones.
Rangitoto Island is a volcanic island in the Hauraki Gulf near Auckland, New Zealand. The 5.5 km (3.4 mi) wide island is a symmetrical shield volcano cone capped by central scoria cones, reaching a height of 260 m (850 ft). Rangitoto is the youngest and largest of the approximately 50 volcanoes of the Auckland volcanic field, having erupted in two phases about 1450 CE and 1500 CE and covering an area of 2,311 ha. It is separated from the mainland of Auckland's North Shore by the Rangitoto Channel. Since World War II, it has been linked by a causeway to the much older, non-volcanic Motutapu Island.
Maungakiekie / One Tree Hill is a 182-metre (597 ft) volcanic peak and Tūpuna Maunga in Auckland, New Zealand. It is an important place culturally and archeologically for both Māori and Pākehā. The suburb around the base of the hill is also called One Tree Hill. It is surrounded by the suburbs of Royal Oak to the west, and clockwise, Epsom, Greenlane, Oranga, and Onehunga. The summit provides views across the Auckland area, and allows visitors to see both of Auckland's harbours.
Takarunga / Mount Victoria is the highest volcano on Auckland's North Shore, rising to 66 metres in elevation. Its age is currently unknown. Its lava flows now line much of Devonport's waterfront. Takarunga was the location of an important pā used by Tāmaki Māori peoples. In the late 19th century, a gun fort was built on top of the hill, in order to defend the city of Auckland. As a designated tūpuna maunga, the mountain has been governed by the Tūpuna Maunga Authority, along with thirteen other cones throughout Auckland, since 2014.
Māngere Mountain, also known by the names Te Pane-o-Mataaho and Te Ara Pueru, is a volcanic cone in Māngere, Auckland. Located within Māngere Domain, it is one of the largest volcanic cones in the Auckland volcanic field, with a peak 106 metres (348 ft) above sea level. It was the site of a major pā and many of the pā's earthworks are still visible. It has extensive panoramic views of Auckland from its location in the southeastern portion of the city's urban area.
North Head is a volcano and Tūpuna Maunga forming a headland at the east end of the Waitematā Harbour in Auckland, New Zealand, in the suburb of Devonport. Known for its sweeping views over the harbour and the Hauraki Gulf, since 1885 the head was mainly used by the military as a coastal defence installation, which left a network of accessible old bunkers and tunnels as its legacy, forming part of the attraction. The site was protected as part of Hauraki Gulf Maritime Park in 1972 and listed as a Category I historic place in 2001. As part of a 2014 Treaty of Waitangi claim settlement the volcanic cone was officially named Maungauika and the reserve unofficially renamed Maungauika / North Head Historic Reserve.
Ōhinerau / Mount Hobson is a 143 m high volcanic cone and Tūpuna Maunga in the Auckland volcanic field in Auckland, New Zealand.
Pigeon Mountain is a 58 m (190 ft) high volcanic cone and Tūpuna Maunga at Half Moon Bay, near Howick and Bucklands Beach, in Auckland, New Zealand. It is part of the Auckland volcanic field.
Achilles Point is a rocky point on the headland at the eastern end of the small sandy beach named Ladies Bay, Auckland, New Zealand. The name 'Te Pane o Horoiwi' can also sometimes refer to the whole headland between St Heliers and Tamaki River estuary. Achilles Point is named after a ship called HMNZS Achilles (70) which defeated the German pocket battleship Admiral Graf Spee in 1939. The headland, from the point round to the Tamaki heads, was previously known as Te Pane o Horoiwi, named after Horoiwi who arrived in New Zealand on the Tainui canoe (waka).
Mount Smart is one of the volcanoes and Tūpuna Maunga in the Auckland volcanic field. A century of quarrying removed almost all the 87 meter scoria cone along with extensive terracing excavated by Māori. The former quarry is now the site of Mount Smart Stadium.
The Auckland Region of New Zealand is built on a basement of greywacke rocks that form many of the islands in the Hauraki Gulf, the Hunua Ranges, and land south of Port Waikato. The Waitākere Ranges in the west are the remains of a large andesitic volcano, and Great Barrier Island was formed by the northern end of the Coromandel Volcanic Zone. The Auckland isthmus and North Shore are composed of Waitemata sandstone and mudstone, and portions of the Northland Allochthon extend as far south as Albany. Little Barrier Island was formed by a relatively isolated andesitic volcano, active around 1 to 3 million years ago.
Crater Hill is one of the volcanoes of the Auckland volcanic field, in New Zealand. It consists of an explosion crater about 600 metres (2,000 ft) wide, partly filled with water. The hill, alongside Māngere Lagoon, Waitomokia, Kohuora, Pukaki Lagoon and Robertson Hill, is one of the volcanic features collectively referred to as Nga Tapuwae a Mataoho, referring to the deity in Tāmaki Māori myths who was involved in their creation.
Matukutūruru is a volcano and Tūpuna Maunga in Wiri, in the Auckland volcanic field. It had a scoria cone reaching 80 metres above sea level, which was quarried away. The lava flows created 290m long Wiri Lava Cave. The hill was the site of a pā. In late 2011 the quarry lake was drained and fill-dumping began on the site.
Ōtāhuhu / Mount Richmond is volcanic peak and Tūpuna Maunga in the Auckland volcanic field. A group of scoria mounds up to 48 m high, it has two 50 m wide craters. It was the site of a pā, and retains some Māori earthworks from that time such as kumara pits and terracing.
Mount Saint John, is a volcanic scoria cone and Tūpuna Maunga in Epsom, in the Auckland volcanic field of New Zealand.
Ōwairaka / Mount Albert, also known as Te Ahi-kā-a-Rakataura, is a volcanic peak and Tūpuna Maunga which dominates the landscape of the Ōwairaka and Mount Albert suburbs of Auckland.
Maungawhau / Mount Eden is a scoria cone and Tūpuna Maunga in the Mount Eden suburb of Auckland, New Zealand. The cone is part of the Auckland volcanic field, the tallest located on the isthmus.
Mount Wellington / Maungarei is a 135-metre volcanic peak and Tūpuna Maunga located in the Auckland volcanic field of Auckland, New Zealand. It is the youngest onshore volcano of the Auckland volcanic field, having been formed by an eruption around 10,000 years ago. It is the largest of Auckland's scoria cones and has a near-circular base with a flattish rim and three small craters. It is situated in the Mount Wellington suburb of East Auckland.
Te Tātua a Riukiuta / Big King is a volcano and Tūpuna Maunga in Three Kings, New Zealand that erupted 28,500 years ago. The volcano had three prominent peaks known as Three Kings and a number of smaller peaks until most of them were quarried away, leaving a sole remaining large peak known as Big King.
Mataaho is a Māori deity. Variously considered a god of earthquakes and eruptions, the guardian of the earth's secrets, the god of volcanic forces, or a giant, Mataaho is associated with many of the volcanic features in the Tāmaki Makaurau Region. In traditional Tāmaki Māori myths, Mataaho either creates the volcanic features of the landscape, or requests the gods to create them. Mataaho holds traditional significance for Te Kawerau ā Maki and Waiohua iwi, and is considered a tupuna (ancestor) of Te Ākitai Waiohua iwi.
The Tūpuna Maungao Tāmaki Makaurau are 14 volcanic cones that hold great historical, spiritual, ancestral and cultural significance to the 13 Māori iwi and hapū of Ngā Mana Whenua o Tāmaki Makaurau, who have owned them since 2014.
1 2 3 Linnell, Tamzin; etal. (2016). "Long-lived shield volcanism within a monogenetic basaltic field: The conundrum of Rangitoto volcano, New Zealand". Geological Society of America Bulletin. 128 (7–8): 1160–1172. Bibcode:2016GSAB..128.1160L. doi:10.1130/B31392.1.
1 2 Hayward, Bruce W.; Murdoch, Graeme; Maitland, Gordon (2011). Volcanoes of Auckland: The Essential Guide. Auckland University Press. ISBN978-1-86940-479-6.
↑ Needham, A.J.; Lindsay, J.M.; Smith, I.E.M.; Augustinus, P.; Shane, P.A. (April 2011). "Sequential eruption of alkaline and sub-alkaline magmas from a small monogenetic volcano in the Auckland Volcanic Field, New Zealand". Journal of Volcanology and Geothermal Research. 201 (1–4): 126–142. Bibcode:2011JVGR..201..126N. doi:10.1016/j.jvolgeores.2010.07.017.
↑ Ian E.M. Smith; Sharon R. Allen (26 January 2010). "Auckland Volcanic Field Geology". Te Pῡ Ao Institute of Geological and Nuclear Sciences. Archived from the original on 9 February 2013. Retrieved 5 January 2023.
1 2 3 New Zealand Department of Conservation (30 March 2007). "Auckland Volcanic Fields". UNESCO World Heritage Centre. Retrieved 5 January 2023.
↑ David Lomas (Winter 2006). "Cave New World". Heritage New Zealand. New Zealand Historic Places Trust. Archived from the original on 20 August 2007.
↑ Rout, D.J.; Cassidy, J.; Locke, C.A.; Smith, I.E. (1993). "Geophysical evidence for temporal and structural relationships within the monogenetic basalt volcanoes of the Auckland volcanic field, northern New Zealand". Journal of Volcanology and Geothermal Research. 57 (1–2): 71–83. Bibcode:1993JVGR...57...71R. doi:10.1016/0377-0273(93)90032-M.
↑ "Visit Volcanoes". Auckland War Memorial Museum. Retrieved 28 September 2017.
↑ Lindsay, J.M.; Leonard, G.S.; Smid, E.R.; Hayward, B.W. (December 2011). "Age of the Auckland Volcanic Field: a review of existing data". New Zealand Journal of Geology and Geophysics. 54 (4): 379–401. doi:10.1080/00288306.2011.595805. S2CID129707270.
↑ Hayward, B.W. (2019). Volcanoes of Auckland. A Field Guide. Auckland University Press. p.334. ISBN978-1-86940-901-2.
↑ Hopkins, Jenni L.; Smid, Elaine R.; Eccles, Jennifer D.; Hayes, Josh L.; Hayward, Bruce W.; McGee, Lucy E.; van Wijk, Kasper; Wilson, Thomas M.; Cronin, Shane J.; Leonard, Graham S.; Lindsay, Jan M.; Németh, Karoly; Smith, Ian E. M. (3 July 2021). "Auckland Volcanic Field magmatism, volcanism, and hazard: a review". New Zealand Journal of Geology and Geophysics. 64 (2–3): 213–234. doi:10.1080/00288306.2020.1736102. S2CID216443777.
↑ Searle, E. J. (May 1962). "The volcanoes of Auckland city". New Zealand Journal of Geology and Geophysics. 5 (2): 193–227. doi:10.1080/00288306.1962.10423108.
Lava and Strata: A guide to the volcanoes and rock formations of Auckland. Homer, Lloyd; Moore, Phil & Kermode, Les; Landscape Publications and the Institute of Geological and Nuclear Sciences, 2000. ISBN0-908800-02-9.
"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 Geology 2003, Portsmouth, UK, 7–12 September 2003.
"Volcanoes". Auckland War Memorial Museum. Retrieved 28 September 2017.
Geology: Rocks and minerals, School of Geography, Geology and Environmental Science, University of Auckland (with interactive maps, requiring Apple QuickTime).
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