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37-563: Orakei Korako is a highly active geothermal area most notable for its series of fault-stepped sinter terraces, located in a valley north of Taupō on the banks of the Waikato River in the Taupō Volcanic Zone , New Zealand . It is also known as "The Hidden Valley". The New Zealand Ministry for Culture and Heritage gives a translation of "place of adornment near the white [sinter flat]" for Ōrākei Kōrako . From earliest times

74-598: A major component of Taupō's commercial sector. The busiest time for the industry is the high summer season around Christmas and New Year. The lake area has a temperate climate. Daily maximum temperatures recorded for Taupō range from an average of 23.3 °C in January and February to 11.2 °C in July, while the nighttime minimum temperatures range from 11.6 °C in February down to 2.2 °C in July. Rain falls in all seasons but

111-502: A new geyser began to erupt in 2001, possibly the beginnings of a further terrace. Also at Orakei Korako is the Ruatapu Cave, one of only two caves in the world known to exist in a geothermal field. The cave extends 45 metres, with a vertical drop of 23 metres, to a shallow pool of clear, sulfate-rich, warm acid water. (The pool's chemical composition gives it the unique ability to clean jewellery.) Another notable feature at Orakei Korako

148-600: A perimeter of approximately 193 km (120 mi) and a maximum depth of 186 m (610 ft). It is drained by the Waikato River (New Zealand's longest river), and its main tributaries are the Waitahanui River , the Tongariro River , and the Tauranga Taupō River . It is a noted trout fishery with stocks of introduced brown and rainbow trout . The level of the lake is controlled by Mercury Energy ,

185-478: Is a beech and podocarp forest with associate understory ferns being Blechnum filiforme , Asplenium flaccidum , Doodia media , Hymenophyllum demissum , Microsorum pustulatum and Dendroconche scandens , and some prominent associate shrubs being Olearia rani and Alseuosmia quercifolia . Native faunal species in the lake include northern kōura or crayfish ( Paranephrops planifrons ) and kōkopu or whitebait ( Galaxias species). The lake

222-502: Is fueled by the presence of a magma chamber. In some rare cases it can be caused by underground fires or by large deposits of radioactive elements. Other sources of internal heating can be gravitational differentiation of substances, tidal friction , metamorphism , or phase transitions . The release of heat to the surface occurs either in the form of a conductive heat flow, or in the form of convective heat transfer by groundwater or gases . Fumaroles, or volcanic vents, are holes in

259-551: Is greatest in winter and spring, from June to December. Taupō hosts the Lake Taupo Cycle Challenge , a cycling tour around the lake which can take anywhere between four and ten hours. Skydiving is a popular local sport and tourist attraction. Taupō also hosts the ANZCO Ironman event. Crossing the 40.2 km length of the lake is a challenge for open-water swimmers. In 2020, Michael Wells from Darwin, Australia,

296-491: Is in a caldera created mainly by a supervolcanic eruption which occurred approximately 25,600 years ago. According to geological records, the volcano has erupted 29 times in the last 30,000 years. It has ejected mostly rhyolitic lava , although Mount Tauhara formed from dacitic lava. Taupō has been active for 300,000 years with a very large event known as the Oruanui eruption occurring approximately 25,600 years ago. It

333-502: Is intended to protect Lake Taupō from volcanic activities underneath. The cliff has become a popular tourist destination with hundreds of boats and yachts visiting the spot yearly. Lake Taupō is a taonga (treasure or something special to the person) of Ngāti Tūwharetoa from the Te Arawa waka. Ngāti Tūwharetoa owns the bed of the lake and its tributaries. They grant the public free access for recreational use. Lake Taupō previously housed

370-400: Is noted for stocks of brown trout ( Salmo trutta ) and rainbow trout ( Oncorhynchus mykiss ), introduced from Europe and California respectively in the late nineteenth century. There has also been a subsequent introduction of smelt ( Retropinnidae species) as a food for the trout. A community of sponges and associated invertebrates live around the underwater geothermal vents. Tourism is

407-463: Is the Soda Fountain, which burst into life in 1984 after a 17-year dormancy. To the south of this feature, high atop a cliff above Lake Ohakuri, are three further geysers, Kurapai, Ellan Vannin and Benedix Washer Geysers, in an area not accessible to the public because it is too dangerous. Temperatures of 100 degrees Celsius (212 degree fahrenheit) have been recorded here just 100 to 150 mm below

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444-602: Is the jade-green Emerald Terrace, the largest of its kind in New Zealand since the presumed destruction of the famed Pink and White Terraces in the Mount Tarawera eruption of 1886. However, researchers recently rediscovered the Pink and White Terrace locations. In peak wet conditions up to 20 million litres of silica -enriched water per day may flow over the terrace and into Lake Ohakuri. The Emerald Terrace continues 35 metres under

481-527: Is the namesake of the town of Taupō , which sits on a bay in the lake's northeastern shore. With a surface area of 616 km (238 sq mi), it is the largest lake by surface area in New Zealand , and the second largest freshwater lake by surface area in geopolitical Oceania after Lake Murray in Papua New Guinea . Motutaiko Island lies in the southeastern area of the lake. Lake Taupō has

518-413: Is unable to reach the surface, causing pressure underground to rise until a critical point is reached and an explosion occurs, ejecting the superheated water along with the rock. Lake Taup%C5%8D Lake Taupō (also spelled Taupo ; Māori : Taupō-nui-a-Tia or Taupōmoana ) is a large crater lake in New Zealand 's North Island , located in the caldera of Taupō Volcano . The lake

555-576: The Minoan eruption in the 2nd millennium BCE, the Tianchi eruption of Baekdu around 1000 CE and the 1815 eruption of Tambora ), with a Volcanic Explosivity Index rating of 7; and there appears to be a correlation, to within a few years, of a year in which the sky was red over Rome and China . The eruption devastated much of the North Island and further expanded the lake. The area was uninhabited by humans at

592-548: The Māori people , meaning "The Cloud"), which is five metres high and 40 metres long, with a beautiful white crystal-like sinter coating. At the base are numerous vents where geysers have come and gone over the years, with the most recent, Wairiri Geyser. Atop this terrace is the Artist's Palette, a 10,000 m² silica sinter terrace covered with clear blue alkali chloride pools and irregularly erupting geysers. To one side of this topmost terrace

629-466: The Horomatangi vent, and nearby geothermal fields with associated hot springs are found north and south of the lake, for example at Rotokawa and Tūrangi . These springs are the site of occurrence of certain extremophile micro-organisms, that are capable of surviving in extremely hot environments. The volcano is considered active and is monitored by GNS Science. Much of the watershed of Lake Taupō

666-500: The Ngāti Tahu vacated the valley to settle at other locations is not recorded, but it has been suggested that they left after the eruption of Mount Tarawera in 1886, when great changes are alleged to have occurred in the hot springs . By the turn of the 20th century all but two families had moved from Orakei Korako. The earliest known route from Rotorua to Taupō for early European travellers passed right through Orakei Korako, and it

703-509: The Waikato Valley near Orakei Korako was occupied by Māori of the Ngāti Tahu sub-tribe of Tuwharetoa . By the early 19th century the Māori population had congregated at Orakei Korako, probably attracted by the hot springs, which they used for cooking and bathing. Around 1819, the local Māori hid in an alum cave on the site from a passing raiding party of Ngāpuhi and Ngati Paoa . The date when

740-465: The artificial lake, Orakei Korako remains the largest geyser field in New Zealand, with up to 35 active geysers . The most famous of these is the Diamond Geyser, whose unpredictable eruptions can last from a few minutes to many hours, ejecting boiling water as high as nine metres. The three terraces above the lakeside Emerald Terrace are great fault scarps formed by an earthquake in 131 AD, around

777-421: The cauldron can be stable or highly variable, and is not related to the nature of the underlaying heat source. Geothermal heat and groundwater can interact in several ways. Geysers are the most well known hydrothermal feature. they occur when groundwater in underground cavities becomes superheated under a lid of colder surface water. When the superheated water breaches the surface, it flashes to steam, causing

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814-421: The flow and propel the punt to the other side. The tourist resort was officially opened on 15 December 1937. The first proposal for power development at Orakei Korako was made in 1904, but it was not until 1955 that the scheme was finally approved. By May 1960 an earth-filled dam, rising 49 metres above the original river level, was placed and consolidated. The filling of Lake Ohakuri began on 19 January 1961 and

851-474: The ground from which volcanic vapors and gases escape to the atmosphere. Geothermally active areas are often located over an active magma chamber , which constantly releases hot gases that travel to the surface through cavities in the rock. Where these cavities reach the surface they form fumaroles. Areas where these vents are concentrated are known as Fumarole fields. Fumaroles tend to form concentrated deposits of sulfuric minerals, which fall out of suspension when

888-603: The ground. Of these geysers , Kurapai Geyser is the most significant, and can sometimes be seen erupting from across the lake in the visitor's centre. The Orakei Korako geothermal system now has some protection from further development, although the nearby Ngatamariki Geothermal Development at Tahorakuri gained resource consent in 2010 despite its possible effects on Orakei Korako. 38°28′24″S 176°8′54″E  /  38.47333°S 176.14833°E  / -38.47333; 176.14833 Geothermal activity Geothermal activity mostly appears in volcanic provinces, where it

925-418: The heated groundwater gathers in pools, forming hot springs. Where very little groundwater is available, rising hot groundwater in combination with microbial activity leads to the formation of mud pots. The behaviour of these mud pots can vary on a seasonal cycle based on variations in the amount of rainfall and the level of the water table. Hydrothermal explosions occur when a mass of superheated water

962-581: The intermittently active Sapphire Geyser, and the Hochstetter Pool (named after Austrian pioneer geologist Ferdinand von Hochstetter , who visited the area in 1859), which erupted in November 1954 and played as a geyser until mid-1955, ceasing suddenly after swarms of subterranean earthquakes. The third and largest great fault scarp in the valley is called the Golden Fleece Terrace (named Te Kapua by

999-433: The lake, which was formed for hydropower generation in 1961. This raised the Waikato River level by 18 metres at Orakei Korako, flooding approximately 200 alkaline hot springs and 70 geysers (or two-thirds of the active thermal area). Some of these thermal features still discharge, with their presence evident as gas bubbles rising from the vents in the lake bed. Despite the loss of so many of its thermal features under

1036-477: The owner of the eight hydroelectric dams on the Waikato River downstream of Lake Taupō, using gates built in 1940–41. The gates are used to reduce flooding, conserve water and ensure a minimum flow of 50 m /s (1,800 cu ft/s) in the Waikato River. The resource consent allows the level of the lake to be varied between 355.85 and 357.25 metres (1,167.5 and 1,172.1 ft) above sea level. Lake Taupō

1073-429: The pressure below it to suddenly drop, which causes a chain reaction where most of the water in the geyser's feed system flashes to steam all at once. There are two main types of geyser. Fountain geysers, which erupt in violent bursts from a pool, and cone geysers, which erupt in steady jets for minutes at a time from a sinter cone of siliceous material that has been deposited surrounding the main vent. In other areas,

1110-630: The time of the eruption, as New Zealand was not settled by Māori until about 1280. Possible climatic effects of the eruption would have been concentrated on the Southern Hemisphere due to the southerly position of Lake Taupō. Taupō's last known eruption occurred around 30 years later, with lava dome extrusion forming the Horomatangi Reefs , but that eruption was much smaller than the Hatepe eruption. Underwater hydrothermal activity continues near

1147-416: The time when Lake Taupō (a supervolcano ) was last erupting. They are mostly covered in hot water algae, or cyanobacteria , which grows in temperatures between 35–59 degrees Celsius (95-138.2 degree fahrenheit), the colours dependent on the species, with green, yellow and black the most common. At the base of the two lower terraces – named Rainbow and Cascade Terraces – are several small geysers, including

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1184-563: The volcanic gases cool to the air. Ice cauldrons are a feature that occurs when an ice cap is affected by geothermal heating, either from active volcanism or the continuous heat production from an active geothermal area. Ice cauldrons can have many different appearances. These range from a smooth dent in the ice cap to deep holes with very steep walls formed by concentric rings of crevasses . The width of ice cauldrons can range from 50 meters up to around 10 kilometers, while depth can range from several meters to hundreds of meters. The shape of

1221-553: Was completed in 14 days. Two of the world's largest geysers were drowned by the lake: Minginui Geyser, which was once observed erupting up to 90 metres high (equal to the world's tallest currently active geyser, Steamboat Geyser in Yellowstone National Park ), and the Orakeikorako Geyser, which on occasion could erupt up to 55 metres, and which gave the whole region its name. The lowest terrace at Orakei Korako

1258-410: Was the existing Māori who provided a dugout canoe for the river crossings. It was at this point in the early 20th century that the geothermal area was established as a visitor attraction. To transfer visitors across the then-swift Waikato River they used the dugout canoe, until in the 1930s a wire-strop and pulley system was erected across the river, and a punt with a guiding rudder was used to catch

1295-523: Was the first to breaststroke across the lake. On the north-west side of Lake Taupō on the cliffs of Mine Bay, there are Māori rock carvings created in the late 1970s by Matahi Whakataka-Brightwell and John Randall. Carved in the likeness of Ngātoro-i-rangi , a navigator who guided the Tūwharetoa and Te Arawa tribes to the Taupō area over a thousand years ago according to Māori legend . The 10-metre-high carving

1332-426: Was the world's largest known eruption over the past 70,000 years, ejecting 1170 cubic kilometres of material and causing several hundred square kilometres of surrounding land to collapse and form the caldera. The caldera later filled with water to form Lake Taupō, eventually overflowing to cause a huge outburst flood . Several later eruptions occurred over the millennia before the most recent major eruption, which

1369-452: Was traditionally dated as about 181 CE from Greenland ice-core records. Tree ring data from two studies suggests a later date of 232 CE ± 5 and this is now accepted. Known as the Hatepe eruption , it is believed to have ejected 100 cubic kilometres of material, of which 30 cubic kilometres was ejected in a few minutes. This was one of the most powerful eruptions in the last 5000 years (alongside

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