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20-564: In the north the Haroharo Caldera has been mapped as extending from the eastern half of Lake Rotoiti to the western border of Lake Rotoma . Its southern extent was defined by the Tarawera volcano . A recent analysis is consistent with the south western structural boundary of the older single event caldera's being in the eastern portions of Lake Tarawera . Both the Okareka Embayment and

40-546: Is therefore not regarded now as a caldera in its own right formed by one single event and there have been many attempts to rationalise the literature from a descriptor used since at least 1962. There have been multiple significant eruptions from the Haroharo vent line , that is parallel and to the north of the Mount Tarawera vent line and also within the Ōkataina Caldera. There has been a large amount of dome infilling that refer to

60-618: The North Island of New Zealand by surface area, and covers 79.8 km . With a mean depth of only 10 metres it is considerably smaller than nearby Lake Tarawera in terms of volume of water. It is located within the Rotorua Caldera in the Bay of Plenty Region . Lake Rotorua is fed with water from a number of rivers and streams; some such as the Utuhina flow with a water temperature warmer than

80-757: The Tarawera Volcanic Complex are adjacent, so many, especially older maps, had these features overlapping the Haroharo Caldera or Okataina caldera as part of the Haroharo volcanic complex or Ōkataina volcanic centre . The Haroharo Caldera was within the older and larger Ōkataina Caldera and its boundaries in geological terms are related mainly to the Matahina and Rotoiti sub-calderas which were formed in single eruption sequences. These boundaries relate to events that happened before about 45,000 years ago. It

100-474: The 1960s, the quality of lake water has been negatively affected by inflows of nitrogen rich water from Lake Rotorua, agricultural run-off from surrounding farms and seepage from domestic septic tanks . The effects of this included an almost permanent algal bloom in the Okere arm of the lake and choking lake weed growth in other still areas of the lake. A barrier to divert the nutrient rich waters of Lake Rotorua into

120-492: The Bay of Plenty near Maketu . The full name of the lake is Te Rotoiti-kite-a-Īhenga , which in the Māori language means "The Small Lake Discovered by Īhenga ", the Māori explorer also credited with discovering Lake Rotorua. Legend says that the lake was named as such because when Ihenga first saw it, he could only see a small part of it and thought the lake was a lot smaller. Since

140-574: The Haroharo name, but the term Ōkataina complex volcano is felt by many to be a better name than the Haroharo volcano to understand the processes that have happened in this portion of the Taupō Volcanic Zone. Within the Haroharo vent line there was a VEI-5 volcanic eruption about 6060 BCE producing about 17 km (4.1 cu mi) of eruptive material and one about 2000 years later that produced 13 km (3.1 cu mi) of material. With its linear parallel young vent alignment to those of

160-566: The Kaituna River was completed in late 2008. The Bay of Plenty Regional Council is expected to see improvement in lake water quality within five years. The Rotorua Te Arawa Lakes Program reported in 2013 that the intervention has significantly improved water quality. Water quality is the highest it has been in decades, and it is on track to meet targets set by the Program to meet community expectations. Lake Rotoiti has thermal hot-spring baths on

180-567: The caldera's Mamaku ignimbrite eruption, related to both volcanic activity and subsidence within the Taupō Rift . The lake all-time high occurred sometime after the formation of the Ngongotahā Dome which records this on its flanks, and is now dated at 200,000 years. Previously this dome's eruption was assigned much closer to the time of the Mamaku ignimbrite eruption, so the lake maximum high stand

200-446: The east, around the base of the active volcano Mount Tarawera and these also over time have varied in size or existence due to volcanic action. Mokoia Island , close to the centre of the lake, is a much later rhyolite dome compared to Ngongotahā. It is probably New Zealand's best-known lake island, and is closely associated with one of the best-known Māori legends, that of Hinemoa and Tutanekai . Is said that Hinemoa swam across

220-500: The emission of gas from decomposition of organic material beneath the lake floor. The surveys also revealed significant geothermal activity extending around 1 km (0.62 mi) into the lake from Sulphur Point. Despite the large volume of water flowing through Lake Rotorua its shallow depth makes it very prone to discolouration, especially from sediment following windy weather. It is well used by fishermen, but less popular with watersports participants and swimmers. The Ohau Channel

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240-583: The floor of Haroharo Caldera Lake Rotoiti (Bay of Plenty) Lake Rotoiti is a lake in the Bay of Plenty region of New Zealand . It is the northwesternmost in a chain of lakes formed within the Okataina Caldera . The lake is close to the northern shore of its more famous neighbour, Lake Rotorua , and is connected to it via the Ohau Channel . It drains to the Kaituna River , which flows into

260-626: The lake due to the thermal activity in the Rotorua area. Conversely streams on the northern shore such as the Hamurana Spring and the Awahou stream flow crystal clear water that has a constant temperature of 10 degrees Celsius. Other notable tributaries include the Ngongotahā stream, famous for trout fishing. Lake Rotorua flows directly into Lake Rotoiti via the Ohau Channel at the north eastern corner of

280-493: The lake to her lover Tutanekai who lived on Mokoia Island. Owing to the geothermal activity around the lake (including still active geysers and hot mud pools), the lake has a high sulphur content. This gives the lake's waters an unusual yellowish-green hue. In 2024, maps of the lake floor were published, showing the results of surveys carried out in 2016 and 2017. The maps reveal the course of an ancient river, now submerged, and thousands of pockmarks that probably result from

300-609: The lake. The urban development of Rotorua extends along the south portion of the lake shore. The lake was formed from the crater of a large volcano in the Taupō Volcanic Zone . Its last major eruption was about 240,000 years ago. After the eruption, the magma chamber underneath the volcano collapsed. The circular depression left behind is the Rotorua Caldera , which is the site of the lake. The lake as shown in Figure 1, has had periods at multiple different lake levels since

320-423: The literature gives a range from 40,000 years to 64,000 years ago with 47,400 ± 1500 years ago being recently quoted. What is not now challenged is that this was a paired eruption with a nearby vent in the Ōkataina Caldera that had a separate magma source and erupted Earthquake Flat breccia . Lake Rotorua Lake Rotorua ( Māori : Te Rotorua nui ā Kahumatamomoe ) is the second largest lake in

340-493: The north western margins of the Ōkataina Caldera itself. This region of the caldera was at one time termed the Haroharo Caldera , but has been renamed in the more standard major event fashion to the Rotoiti Caldera . As postulated, this caldera does not house the lake. The age of this large eruption of more than 100 cubic kilometres (24 cu mi) of magma was historically ill-defined due to several complexities and

360-466: The similarly young in geological terms, Tarawera volcano, and related magma sources, this means it is now usually regarded as a subsidiary volcanic part of the Ōkataina Caldera which in the last 21,000 years has contributed a total magma eruptive volume greater than about 80 km (19 cu mi). HaroHaro pile ... are rhyolite lavas of the Okataina Volcanic Centre, extruded on

380-504: The southern shore which are accessible by boat. Its joint drainage with Lake Rotorua through the Ohau Channel depends upon the sinking Tikitere graben which is also very geothermally active on the south eastern margins of the lake. There appear to have been Rotoiti eruptive vents at the eastern end of the lake and although these are part of the Ōkataina Volcanic Centre they are believed to be in an area of collapse subsidence outside

400-648: Was assumed to be more directly related to the caldera's formation. Breakout floods are suspected through the Hemo Gorge after the lake's maximum high stand, definitely after the Rotoiti eruption of the Ōkataina Caldera , with formation of a channel within the western lake floor of Lake Rotoiti and suspected after the Hauparu eruption through the Kaituna River Gorge. Several other lakes of volcanic origin are located nearby to

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