Ruapehu District is a territorial authority in the centre of New Zealand 's North Island .
84-578: Tangiwai is a 2,696.66 km (1,041.19 sq mi) census area and a small rural community in the Ruapehu District of the Manawatū-Whanganui region of New Zealand's North Island . It is located east of Ohakune and Rangataua and west of Waiouru on State Highway 49 . In 2018 37.5% of the area's 1,281 residents worked in agriculture, forestry and fishing and 7.1% in manufacturing. The New Zealand Ministry for Culture and Heritage gives
168-446: A polar tundra climate ( Köppen : ET ) on the upper slopes, with average temperatures ranging from −4–15 °C in summer and −7–7 °C in winter, depending on elevation and cloudiness. On the lower slopes, Ruapehu has a subpolar oceanic climate (Köppen: Cfc ). The prevalent wind direction in the region is westerly or northwesterly, and gale force conditions (i.e. wind speeds higher than 33 kn (61 km/h)) are common on
252-507: A snow cave and sheltered in it until he was rescued days later. Extreme weather conditions have caused visitors to be trapped on the mountain in the past. In 2003, about 350 visitors to Whakapapa skifield and 70 staff had to stay overnight in various lodges at Iwikau village (small village at the top of mountain road) after a snow storm made the road too dangerous to descend. In 2008 extreme weather resulted in about 2000 visitors being evacuated from Whakapapa skifield, with cars being led down
336-589: A 22-year-old primary school teacher, had a leg pinned and crushed by a boulder as the water subsided. A rescue operation was mounted after his companion, who was unable to free him, went down the mountain for help. The eruption initiated lahars down the Whangaehu valley and the Whakapapa skifield . ERLAWS detected the lahars in the Whangaehu valley. A snow groomer on the Whakapapa skifield narrowly avoided being caught in
420-541: A club Tukino field on the east of the mountain. The commercial developments have not been a consistent success, with at least two business failures by 2023. While as of 2001, Mount Ruapehu had the largest total ski area in New Zealand, developments in the South Island may see by 2025 the establishment there of the largest single commercial ski area in New Zealand. A 60-year concession for commercial ski field operation
504-431: A crater wall collapse and alert the relevant authorities. It began operating in 2002. The lake gradually filled with snowmelt and had reached the level of the hard rock rim by January 2005. The lahar finally occurred on 18 March 2007 (see below). Ruapehu erupted at 10:24 p.m. on 4 October 2006. The small eruption was marked by a magnitude 2.9 volcanic earthquake and sent waves 4–5 m (16 ft) tall crashing into
588-701: A population of 1,281 at the 2018 New Zealand census , an increase of 54 people (4.4%) since the 2013 census , and a decrease of 87 people (−6.4%) since the 2006 census . There were 492 households, comprising 675 males and 606 females, giving a sex ratio of 1.11 males per female. The median age was 40.0 years (compared with 37.4 years nationally), with 279 people (21.8%) aged under 15 years, 210 (16.4%) aged 15 to 29, 642 (50.1%) aged 30 to 64, and 150 (11.7%) aged 65 or older. Ethnicities were 78.2% European/ Pākehā , 34.0% Māori , 2.6% Pacific peoples , 2.6% Asian , and 1.2% other ethnicities. People may identify with more than one ethnicity. The percentage of people born overseas
672-621: A public meeting in Raetihi on 27 August, Mayor of Ruapehu Weston Kirton urged the New Zealand Government to offer an electrical subsidy to Winstones' mills. National Party Member of Parliament Suze Redmayne responded that the Government was working with electrical utility companies to find solutions. On 10 September 2024, the company confirmed that it would close down its Karioi pulp mill and Tangiwai timber mill by October 2024, leading to
756-573: A significant hazard to surrounding river valleys, particularly the Whangaehu River, which is crossed by national highways, the North Island Main Trunk railway line, and electricity transmission lines. Large, destructive lahars have been observed in the Whangaehu River in 1862, 1895, 1953, 1975, and 2007. GNS Science continuously monitors Ruapehu using a network of seismographs, GPS stations, microphones and webcams. Chemical analysis of
840-451: A translation of "weeping water" for Tangiwai . New Zealand's worst rail accident, the Tangiwai disaster , occurred near Tangiwai on 24 December 1953. The Whangaehu River rail bridge collapsed beneath a Wellington-to-Auckland express passenger train. The locomotive and first six carriages derailed into the river, killing 151 people. The subsequent Board of Inquiry found that the accident
924-664: A year, using 200,000 m (7,100,000 cu ft) of logs, a planer, optimiser, dry-sheds, kilns and a 5 MW (6,700 hp) wood waste heat plant, added in 2001. In April 2008, Ernslaw One Ltd purchased WPI. Ernslaw One owned by the Malaysian Tiong Family, bought WPI for $ 117,293,314. WPI employed about 300 staff. At 30 September 2006, its forest crop was valued at $ 83m and its fixed assets at $ 38.7m. It earned $ 131m, but lost $ 10.1m. Ernslaw One also has forests and mills in Gisborne , Naseby and Tapanui . A further use for
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#17328592824941008-399: Is also home to the world-famous Raurimu Spiral on the North Island Main Trunk railway line . The tourist towns of Raetihi , Whakapapa Village , National Park, and Ohakune are located near Mount Ruapehu in the south-east of the district. Waiouru, with an elevation of 815 metres, is in the extreme south-east of the district and houses the large Waiouru Army Camp . The southern section of
1092-616: Is an active stratovolcano at the southern end of the Taupō Volcanic Zone and North Island volcanic plateau in New Zealand . It is 23 km (14 mi) northeast of Ohakune and 23 km (14 mi) southwest of the southern shore of Lake Taupō , within the Tongariro National Park . The North Island 's major ski resorts and only glaciers are on its slopes. Ruapehu, the largest active volcano in New Zealand, has
1176-643: Is made up of 12 elected councillors, including a mayor and deputy mayor. The district is also served by 2 Community Boards and a Ward Committee, with the same functions and powers as the Community Boards. In the 2022 local body elections, there were two wards, a general ward and a Māori ward. The current mayor of the Ruapehu District is Weston Kirton, the deputy mayor is Vivienne Hoeta. Mount Ruapehu Mount Ruapehu ( Māori: [ˈɾʉaˌpɛhʉ] ; English / ˈ r uː ə ˌ p eɪ h uː / )
1260-831: Is presently active, a deep crater at the southern end of the summit plateau which is filled with hot, acidic water, dubbed Crater Lake (Te Wai ā-moe). The lake water currently covers separate north and central vents. Ruapehu sits on a basement of Mesozoic greywacke overlain by a thin layer of sediments of the Wanganui Basin , composed of sands, silts, shell beds, and limestone . It has not been clearly established when Ruapehu first began erupting, only that eruptions began at least 250,000 years ago and possibly as early as 340,000 years ago. Ruapehu has been built in four distinct stages of relatively intense eruptive activity followed by periods of relative quiet. Each of these four stages of activity has left behind distinct rock formations, named
1344-788: The 2018 census , and an increase of 1,251 people (10.6%) since the 2013 census . There were 6,720 males, 6,333 females and 42 people of other genders in 5,412 dwellings. 2.3% of people identified as LGBTIQ+ . The median age was 39.0 years (compared with 38.1 years nationally). There were 2,799 people (21.4%) aged under 15 years, 2,217 (16.9%) aged 15 to 29, 5,688 (43.4%) aged 30 to 64, and 2,391 (18.3%) aged 65 or older. People could identify as more than one ethnicity. The results were 68.8% European ( Pākehā ); 45.7% Māori ; 3.5% Pasifika ; 3.6% Asian ; 0.6% Middle Eastern, Latin American and African New Zealanders (MELAA); and 2.3% other, which includes people giving their ethnicity as "New Zealander". English
1428-464: The Ngāti Rangi hapū of Ngāti Rangihaereroa , Ngāti Rangiteauria and Ngāti Tongaiti . Tangiwai statistical area, which includes Rangataua and which surrounds but does not include Raetihi , Ohakune and Waiouru , covers 2,696.66 km (1,041.19 sq mi) and had an estimated population of 1,420 as of June 2024, with a population density of 0.53 people per km. The statistical area had
1512-647: The North Island of New Zealand, 23 km (14 mi) northeast of Ohakune , New Zealand and 23 km (14 mi) southwest of the southern shore of Lake Taupō , within Tongariro National Park. Ruapehu is the largest and southernmost volcano in the national park, with an estimated volume of 110 km . The volcano is surrounded by a ring plain of volcanic material, made from lahar deposits, ash fall, and landslide debris. There are three access routes to Ruapehu, and each access route leads to one of
1596-410: The Ruapehu District and cause families to migrate to Australia for work in the timber industry. First Union and E tū issued a joint statement describing the mills' closure as "devastating." First Union general secretary Dennis Maga thanked the local mayors and Associate Energy Minister Shane Jones for fighting to keep the mills open but criticised the Government for not intervening to address
1680-572: The 1945 eruptions collapsed on 24 December 1953, sending a lahar down the Whangaehu River and causing the Tangiwai disaster . 151 people died when the lahar swept away the Tangiwai railway bridge just before an express train crossed it. Another dam was deposited by the 1995–1996 eruptions, which collapsed on 18 March 2007. A warning system, the Eastern Ruapehu Lahar Alarm and Warning System (ERLAWS) system began operation on
1764-779: The Desert Road ( State Highway 1 ) to the Tukino skifield on the eastern slopes. Ruapehu's active crater, dubbed Crater Lake (Te Wai ā-moe), is situated at the southern end of the Summit Plateau, and as the name suggests, is filled with a warm, acidic lake. The lake's outlet is at the head of the Whangaehu Valley, where the Whangaehu River arises. The Whangaehu River is notorious for destructive lahars caused by Ruapehu's eruptions. In historic times, eruptions have built tephra dams across
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#17328592824941848-545: The Government for not doing more to keep the mills open. Ruapehu District It has an area of 6,734 square kilometers and the district's population in June 2024 was 13,550. The district is landlocked, and contains the western half of the Tongariro National Park , including Mount Ruapehu and the western sides of Mount Ngauruhoe and Mount Tongariro , as well as part of the Whanganui National Park . The district
1932-802: The Taupō Hatepe eruption in 232 CE. Over this period there are 30 assigned tephra units by composition studies to Ruapehu and in the 370 years before 1950 the mean time between these months of eruptive period was 40 years. In recorded history, these eruptions have occurred about 50 years apart, in 1895 ( lahar ), 1945 and 1995–1996. Minor phreatic or hydrothermal eruptions occur every few years on average, with notable minor eruptions occurring in 1969, 1975, and 2007. More than 600 eruptive events of various sizes have been documented since 1830. Ruapehu entered an eruptive phase in March 1945 after several weeks of volcanic tremors. The first indication of an eruption
2016-682: The Te Herenga Formation (erupted 250,000–180,000 years ago), the Wahianoa Formation (erupted 160,000–115,000 years ago), the Mangawhero Formation (erupted 55,000–15,000 years ago), and the Whakapapa Formation (erupted 15,000–2,000 years ago). Each of these rock formations is composed of lava flows and tuff breccias , and studies of these formations has revealed how volcanic activity at Ruapehu has developed over time. During
2100-447: The Te Herenga Formation, and today these formations be seen at Pinnacle Ridge, Te Herenga Ridge, and Whakapapanui Valley, all on the northwestern slopes of Ruapehu. Approximately 160,000 years ago, cone-building eruptions began again, this time from a crater that is thought to have lain northwest of present-day Mitre Peak (Ringatoto)—southeast of the original Te Herenga vent. Eruptions continued until approximately 115,000 years ago, and
2184-483: The Te Herenga stage of activity, magma rose quickly through the crust during eruptions. However, by 160,000 years ago a complex network of magma dikes and sills had formed in the crust under the volcano, and lava erupted since that time shows signs of extensive mixing between different magma chambers prior to eruptions. In modern times, volcanic activity has been centred on Crater Lake. There are two active vents under
2268-423: The active crater: one on the north side of the crater under Paretetaitonga Peak and another one to the south, and these are New Zealand's only crater glaciers. Most of the ice on Ruapehu is contained in only three of its glaciers: the Whangaehu, Summit Plateau, and Mangatoetoenui glaciers. The Summit Plateau glacier is not a glacier in the true sense, but rather an ice field that fills an extinct volcanic crater, and
2352-583: The aquatic life downstream. Additionally, the lahars damaged ski installations on the Whakapapa ski field, several bridges and hydroelectric tunnel intakes, but no loss of life occurred. Three days later, on the morning of 27 April, Ruapehu erupted again. A series of five eruptions occurred between 7:10 a.m. and 10:18 a.m., sending surges of mud, rocks, and ash northwards across the summit plateau and producing eruption columns up to 500 m high. The 1975 eruptions deepened Crater Lake from 55 to 60 m to more than 90 m. Earthquake swarms to
2436-415: The census question. Of those at least 15 years old, 957 (9.3%) people had a bachelor's or higher degree, 5,967 (58.0%) had a post-high school certificate or diploma, and 3,096 (30.1%) people exclusively held high school qualifications. The median income was $ 33,800, compared with $ 41,500 nationally. 597 people (5.8%) earned over $ 100,000 compared to 12.1% nationally. The employment status of those at least 15
2520-423: The crater, sent lahars down three valleys, and generated an eruption column 12 km high. Phreatomagmatic eruptions occurred through the rest of the month and throughout October, with some eruptions continuing for hours at a time. Ash fell up to 250 km downwind. Explosive eruptions on 11 October emptied Crater Lake of water. Following this, activity died off until 15 June 1996 when renewed seismic activity
2604-430: The day, and mountain visitors are advised to be prepared and carry basic survival equipment. Severe weather has claimed several lives over the years, including a party of five NZ Army soldiers and one RNZN naval rating, caught in a week-long storm while undergoing winter survival training in 1990. The same storm also trapped an experienced Japanese mountaineer when the weather unexpectedly closed in on him, but he built
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2688-548: The deaths of livestock. Ash in the Tongariro River also damaged the intake turbines at the Rangipo power station, and ash clouds caused airport closures as far away as Auckland and Wellington . The eruptions also caused closures to the three ski fields on the mountain, costing the region an estimated $ 100 million in lost revenue. During the 1995–1996 summer period between the eruptions, Ruapehu Alpine Lifts ran its chairlifts up
2772-747: The early hours of 21 August was heard in Hawkes Bay and the Tararua District , loud enough to awaken people from sleep and cause alarm. Eruptions began declining in December and had ended by January. The eruptions dispersed ash across most of the North Island, and eruption columns could be seen from as far afield as Palmerston North , Whanganui , and Hawkes Bay . Ash caused disruption to several North Island communities, entering houses, causing eye and throat irritation, and damaging paintwork on cars. Crop damage
2856-447: The early hours of 22 June. It was a moderate phreatic eruption, which blasted rocks up to 1 km northwest of the crater and sent lahars down several valleys. The Whakapapa skifield was left covered in mud. This was the largest eruption since 1945. A larger phreatic eruption occurred at 3:59 a.m. on 24 April 1975, blasting rocks up to 1.6 km northwest of the crater, against the wind, and depositing ash more than 100 km to
2940-416: The eruption lasted for less than a minute and blasted ash, mud, and rocks northward, reaching to about 2 km from Crater Lake. Two climbers were caught in the eruption at Dome Shelter, an alpine hut approximately 600 m from the crater, when the hut was struck by the surge. The climbers nearly drowned before the hut floor gave way and the water drained into the basement seismometer vault. One of them,
3024-523: The government sold its interests. The last remaining director from the Winstone family, Donald, retired. In early 1988, Fletcher Challenge bought Winstone for $ 444m. Karioi was sold within months to a Hong Kong investment company. The current name of Winstone Pulp International Ltd was adopted. WPI was sold to Ernslaw One group in 2008. In August 2024, Winstone Pulp International proposed closing its two central North Island mills due to high power prices. During
3108-456: The highest point in the North Island and has three major peaks: Tahurangi (2,797 m), Te Heuheu (2,755 m) and Paretetaitonga (2,751 m). The deep, active crater is between the peaks and fills with water between major eruptions, being known as Crater Lake ( Māori : Te Wai ā-moe ). The name Ruapehu means "pit of noise" or "exploding pit" in Māori . Ruapehu is located in the centre of
3192-618: The ice there reaches more than 130 m thick. The Whangaehu glacier feeds the Whangaehu River, and the Mangatoetoenui glacier is one of the principal sources of the Waikato River , which arises as a series of streams on Ruapehu's eastern slopes. On the western side of the mountain, many of the streams that arise there, such as the Whakapapa and Manganui o te Ao rivers, feed the Whanganui River . Ruapehu's glaciers are situated at
3276-634: The impact of its previous energy reforms. Ruapehu Mayor Kirton described the mills' closures as a "massive blow to Ruapehu and our communities." He confirmed that the Ruapehu District Council would work with WINZ and its iwi partners to support affected workers. Energy Minister Simeon Brown defended the New Zealand Government's decision not to intervene, describing it as a "commercial decision." In response, Labour 's small business and manufacturing spokesperson Helen White criticised
3360-421: The infamous Desert Road section of State Highway 1 runs through the east of the district, from Waiouru to Rangipo . Ruapehu District covers 6,734.44 km (2,600.18 sq mi) and had an estimated population of 13,550 as of June 2024, with a population density of 2.0 people per km . Ruapehu District had a population of 13,095 in the 2023 New Zealand census , an increase of 786 people (6.4%) since
3444-553: The lahar there. Only one eruptive event has been recorded at Ruapehu since the 2007 eruption—a minor event on 13 July 2009 when a small volcanic earthquake beneath Crater Lake caused the lake water level to rise 15 cm and triggered a snow slurry lahar in the upper Whangaehu valley. Since then, Crater Lake has continued its regular cycle of heating and increased gas emissions, although with periods of sustained high temperatures that occurred in 2011, 2016 and 2019. Eruptions at Ruapehu are expected to continue much as they have for
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3528-647: The lake, dubbed North Vent and Central Vent. Activity is characterized by cyclic heating and cooling of the lake over periods of 6–12 months. Each heating cycle is marked by increased seismic activity under the crater and is accompanied by increased emission of volcanic gases , indicating that the vents under Crater Lake are open to gas escape. Evidence suggests that an open-vent system such as this has been in place throughout Ruapehu's 250,000 year history. This prevents build-up of pressure and results in relatively small, frequent eruptions (every 20–30 years on average) at Ruapehu compared to other andesitic volcanoes around
3612-442: The late 1960s. Winstone Pulp International (WPI) bought 13,893 ha (34,330 acres) of Waimarino Forest in 1989 and cutting rights to 11,056 ha (27,320 acres) of Karioi Forest in 1990. To cut the timber, MSD Spiers built Tangiwai Sawmill beside the railway station in 1966. It was bought by nearby pulp mill owner, Winstone Pulp International Ltd (WPI), in 1993 and upgraded to mill over 100,000 m (3,500,000 cu ft)
3696-399: The lava erupted during this period is known as the Wahianoa Formation. This formation has also been heavily eroded by glacial activity, and it now forms the southeastern flanks of modern Ruapehu. The formation consists of lava flows and tuff breccias . Beginning approximately 55,000 years ago, a third phase of cone-building eruptions began, creating the Mangawhero Formation. This formation
3780-502: The loss of 151 lives when the Tangiwai railway bridge across the Whangaehu River collapsed while the lahar was in full flood, just before an express train crossed it. Ruapehu saw a period of heightened activity between 1966 and 1982, with multiple small eruptions occurring in Crater Lake and two larger eruptions in 1969 and 1975, which ejected rocks across the summit region and produced significant lahars. The eruption in 1969 occurred in
3864-653: The loss of 230 jobs. WPI chief executive Mike Ryan attributed the closure to the "dual impact" of "uncompetitive" energy prices in New Zealand and the relatively low current and forecast mark prices for pulp and timber." Ryan confirmed that WPI would support staff by helping them to find jobs with other industry players, work with the Ministry of Social Development and Inland Revenue Department to support retrenched staff and provide access to wellbeing providers and financial advisers. WPI had previously criticised high power prices for making its business operations unsustainable, which
3948-533: The mill came on stream in 1979, prices for pulp and newspaper had fallen and the pulp was of variable quality. In 1981 the mill was caught up in the Think Big debate, when the government took $ 10m in preference shares and made a $ 5m loan. Losses that year were $ 7.133m and rose to $ 11m. Later in 1981 H.W. Smith Ltd, a company linked with Brierley Investments Ltd , increased its 10% holding in Winstone to 24.9% and to 27% in 1983. Brierley gained full control of Winstone when
4032-459: The mountain and organised guided tours to within 500 metres of the crater. Hundreds of tourists visited, even though the volcano was still emitting steam and toxic sulphur gas and the Department of Conservation was warning that further eruptions were possible. Both the 1995 and 1996 eruptions were filmed and streamed to the internet via a custom-built 'volcano-cam', possibly the first such camera in
4116-478: The mountain in 2002 to detect such a collapse and alert the relevant authorities. The ERLAWS system detected the 2007 lahar, and roads were closed and railway traffic stopped until the lahar had subsided. The earliest known volcanic activity in Tongariro National Park was approximately 933,000 ± 46,000 years ago at Hauhungatahi , northwest of Ruapehu. Subsequently, andesitic clasts found 100 km southwest of Ruapehu, near Whanganui , demonstrate that volcanism
4200-734: The mountain in groups of five. About 100 cars were left at the skifield overnight. Ruapehu is a composite andesitic stratovolcano located at the southern end of the Taupō Volcanic Zone and forming part of the Tongariro Volcanic Centre. Volcanism at Ruapehu is caused by the subduction of the Pacific Plate under the Australian Plate at the Hikurangi Trough to the east of the North Island . Ruapehu has erupted from multiple craters over its lifetime, however, only one crater
4284-421: The mountain was sacred, and said: "as far as we are concerned if these things [lahars] do happen well we step aside. Let them go past". Other plans considered were building a stop bank on the Desert Road, or creating an early-warning system, which would be much more expensive than digging a trench. In 2001, the Eastern Ruapehu Lahar Alarm and Warning System (ERLAWS) system was installed on the mountain to detect
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#17328592824944368-457: The mountain's high peaks as well as the Turoa skifield . Medium size tephra eruptions of Ruapehu since the 232 CE Taupo eruption Lava flows that have been erupted from Ruapehu since the last glacial maximum are called the Whakapapa Formation. These flows all erupted between 15,000 and 2,000 years ago from a number of different craters on the summit of Ruapehu as well as from craters on
4452-464: The mountain. Rainfall is higher on the western flanks of Ruapehu than the eastern flanks due to the rain shadow effect. Whakapapa Village receives an average of 2,200 mm of rain per year, whereas the Rangipo Desert to the east of Ruapehu receives slightly more than 1,500 mm of rain annually. Snow falls on average as low as 1,500 m elevation. Weather conditions can be changeable over
4536-565: The northern and southern flanks of the mountain. Rangataua on the southern flanks had a large lava flow between 15,000 and 10,000 years ago. Approximately 10,000 years ago, a series of major eruptions occurred, not just on Ruapehu, but also at the Tama Lakes between Ruapehu and Tongariro volcanoes. This period of intense eruptions is called the Pahoka-Mangamate event and is thought to have lasted between 200 and 400 years. On Ruapehu, lava
4620-411: The northern limit for the formation of permanent ice in New Zealand, and thus they are extremely sensitive to changes in climate. Surveys of the glaciers undertaken since 1955 have found that the glaciers have all been thinning and retreating, with the exception of the northern crater glacier, which thickened and lengthened after the 1953 outburst of Crater Lake lowered the lake water level. Ruapehu has
4704-411: The northwestern ring plain that can still be seen today. Since then eruptions have been an order of magnitude lower in intensity and volume. Accordingly, most of the 150 km (36 cu mi) cone and 150 km (36 cu mi) ring-plain is older than 10,000 years. Eruptions between 10,000 and 2,500 years ago generated lava flows that all flowed into the Whakapapa amphitheatre and created
4788-419: The ones in 1995–96 have only occurred within periods of enhanced activity. The main recent volcanic hazard at Ruapehu is from lahars. Two major lahar paths run through the Whakapapa skifield, and in recent times, lahars have travelled through the ski field in 1969, 1975, 1995, and 2007. An eruption warning system operates in the ski field to warn skiers in the event of another eruption. Lahars also represent
4872-447: The outlet on several occasions, most recently in 1945 and 1996. These dams failed in 1953 and 2007 respectively, causing an outburst of Crater Lake each time, which sent destructive lahars down the river. The 1953 lahar was the cause of the Tangiwai disaster , in which 151 people died. Even larger lahars occurred in 1862 and 1895. A total of 18 glaciers have been recognised on Ruapehu, of which six are named. Two glaciers are found in
4956-488: The past 2,000 years, with frequent minor eruptions and more significant events every 20–30 years, although the possibility of larger events like the Pahoka-Mangamate event cannot be ruled out. The previous activity trend until 10,000 years ago was about 7.5 km (1.8 cu mi) erupted each 10,000 years. Minor eruptions, such as the one in 2007, especially if they are hydrothermal, can occur at any time without warning. However, in historic times, major eruptions such as
5040-428: The pulp, electricity and LPG supplying the other energy. Excess heat is used to dry timber from the sawmill. In 2004 the mill had 145 staff. In 1976 Winstone and Chonju Paper Manufacturing, a Samsung subsidiary, built a thermo-mechanical pulp mill , almost 3 km (1.9 mi) north of the sawmill. In 1978 the first load of logs was delivered to the mill. At least 70% of the pulp was to go to Chonju, but, when
5124-412: The slopes of the modern skifield. For the past 2,000 years, activity at Ruapehu has been largely focused through a crater lake at the summit. Eruptive activity has typically consisted of relatively small but explosive phreatomagmatic eruptions occurring every few decades and lasting several months each. The eruptive record is only well understood from tephra deposits before 1950 for 1718 years from
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#17328592824945208-431: The southeast. Nine minutes of seismic activity preceded the eruption, but crater dilation had been measured two weeks earlier. Nearly half of the water in Crater Lake was erupted into the air, which subsequently rained down onto the summit, generating lahars down several river valleys. Lahars which travelled down the Whakapapa and Manganui o te Ao rivers entered the Whanganui River and poisoned it, which affected much of
5292-400: The three skifields that are found on its slopes. State Highway 48 leads to Whakapapa Village at the base of the mountain, and from there an access road leads up the mountain to Iwikau Village at the base of the Whakapapa skifield on the northwestern bumpy hilly slopes. An access road from Ohakune leads to Turoa skifield on the southwestern slopes, and a four-wheel drive track leads from
5376-425: The timber was the pulp mill, though it had a troubled beginning. It produces 100,000 m (3,500,000 cu ft) a year when running a single-shift. It is mainly used for newsprint and paperboard , much of it exported through New Plymouth , then CentrePort Wellington and now Napier . A 12 MW (16,000 hp) bark furnace and a heat exchanger recover 3 MW (4,000 hp) of heat from steam for drying
5460-539: The wall of the crater. No ash was erupted into the atmosphere, and the eruption is presumed to have occurred entirely underwater. At 11:22 a.m. 18 March 2007, the tephra dam which had been holding back Crater Lake burst, sending a lahar down the mountain. An estimated 1.9–3.8 million cubic metres of mud, rock, and water travelled down the Whangaehu river. ERLAWS activated, sending an alarm to pagers at 11:25 a.m. and automatically activating warning lights and barrier arms to close roads and stop trains. There
5544-462: The walls of the crater and damaged some monitoring equipment there. A second eruption on 29 June destroyed the equipment and produced a lahar. Chemical analysis showed that magma was interacting with water under the lake. The first significant eruption took place at 8:05 a.m. on 18 September 1995, raining tephra onto the summit region and sending lahars down the mountain. On 23 September, an even larger eruption blasted rocks up to 1.5 km from
5628-463: The water in Crater Lake is regularly undertaken along with airborne gas measurements. Live data can be viewed on the GeoNet website . The mountain, as part of Tongariro National Park is host to a wide range of recreational activities. Since the first ski field developments in 1923, Ruapehu has had three ski areas developed, Whakapapa on the north-western side, Tūroa on the south western slopes, and
5712-523: The west of Ruapehu between November 1994 and September 1995 marked the beginning of renewed heightened activity at the volcano. Bursts of earthquake activity immediately preceded rapid rises in the temperature of Crater Lake, with the surface temperature reaching 51.4 °C in January 1995—one of the highest temperatures recorded in 30 years and about 10 °C higher than its usual peak temperature. A minor eruption occurred on 26 April, which sent waves against
5796-472: The world. Crater Lake is emptied by major eruptions, such as the ones in 1945 and 1995–1996, but refills after eruptions subside, fed by melting snow and vented steam. In historic times, major eruptions have deposited a tephra dam across the lake's outlet, preventing lake overflow into the Whangaehu valley. The dam collapses after several years causing a large lahar down the valley. The tephra dam created by
5880-477: The world. The website hosting the feed during the 1996 eruption received up to 4000 hits an hour. After the 1996 eruption it was recognised that a catastrophic lahar could again occur when Crater Lake burst the volcanic ash dam blocking the lake outlet as it did in 1953. In 1997, the government proposed digging a trench through the blockage in the wall of Crater Lake, but this was plan was opposed by conservation groups and Māori. A Ngāti Rangi spokesman noted that
5964-511: Was $ 30,500, compared with $ 31,800 nationally. 141 people (14.1%) earned over $ 70,000 compared to 17.2% nationally. The employment status of those at least 15 was that 606 (60.5%) people were employed full-time, 144 (14.4%) were part-time, and 39 (3.9%) were unemployed. George Syme & Co ran a saw mill to cut totara , rimu , matai and kahikatea , linked to the station by a 1 + 1 ⁄ 4 mi (2.0 km) tramway from 1908 until 1930. The mill burnt down in 1926. Karioi state forest
6048-448: Was 10.1, compared with 27.1% nationally. Although some people chose not to answer the census's question about religious affiliation, 55.0% had no religion, 31.9% were Christian , 4.4% had Māori religious beliefs , 0.2% were Muslim , 0.2% were Buddhist and 1.2% had other religions. Of those at least 15 years old, 126 (12.6%) people had a bachelor's or higher degree, and 198 (19.8%) people had no formal qualifications. The median income
6132-416: Was caused by the collapse of the tephra dam holding back nearby Mount Ruapehu 's crater lake, creating a large lahar in the Whangaehu River, which destroyed one of the bridge piers at Tangiwai only minutes before the train reached the bridge. A memorial has been built at the accident site. Tirorangi Marae and Rangiteauria meeting house is located in the Tangiwai area. It is a traditional meeting ground of
6216-441: Was disputed by electrical utility company Mercury Energy . On 5 August, the company had also temporarily paused operations at both Karioi and Tangiwai, citing high energy prices. In response to WPI's closure proposal, workers had unsuccessfully petitioned to save the mills and made 189 submissions to improve the mills and cut down on costs. RNZ reported that many employees had said that the mill's closure would lead to job losses in
6300-437: Was erupted from Saddle Cone—a flank crater on the northern slopes—and from another crater on the southern slopes. This southern crater erupted three times, and lava flows from this crater travelled nearly 14 km to the south. There is evidence that a sector collapse on the northwestern slopes about 9,400 years ago formed the amphitheatre that now comprises the Whakapapa skifield and left an extensive avalanche deposit on
6384-492: Was erupted onto the eroded Wahianoa Formation in two phases: the first occurring 55,000–45,000 years ago and the second 30,000–15,000 years ago. Multiple summit craters were active during this period, all lying between Tahurangi and the northern summit plateau. Parasitic eruptions also occurred at Pukeonake, a scoria cone to the north-west of Ruapehu and at several isolated craters near Ohakune . The Mangawhero Formation can be found over most of modern Ruapehu, and it forms most of
6468-555: Was likely present in the Ruapehu area 340,000 years ago. However, the oldest rocks on Ruapehu itself are approximately 250,000 years old. Eruptions during this period are believed to have built a steep volcanic cone around a central crater, which would have been located somewhere near the present-day upper Pinnacle Ridge. Cone-building eruptions ceased about 180,000 years ago, and the cone began to be eroded away by glacial action. Rock formations that date to this period are collectively named
6552-460: Was no serious damage and no injuries. A toilet block at the Tangiwai memorial was destroyed, but the memorial had already been closed due to the lahar threat. One family was trapped for around 24 hours after the lahar swept away the access route to their home. At 8:16 p.m. on 25 September 2007, volcanic tremor was detected underneath Ruapehu, which was followed at 8:26 p.m. by an explosive surtseyan eruption. The explosive phase of
6636-437: Was recorded. This was followed by eruptions on 17 and 18 June which once again emptied the partially refilled Crater Lake of water. Strombolian eruptions occurred on 27 June and throughout July and August, producing eruption columns more than 10 km high and shooting rocks 1.4 km from the crater. These eruptions produced more than 7 million tonnes of ash, which contaminated water supplies, destroyed crops, and lead to
6720-477: Was reported in Ohakune, and the water supply at Taumarunui was disrupted. After eruptions subsided in late December, Crater Lake slowly began refilling, with a "boiling lake" already filling the bottom of the crater by mid-January. A tephra dam had formed at the lake's normal outlet during the eruptions, which eventually collapsed on 24 December 1953 causing a lahar that led to the Tangiwai disaster with
6804-478: Was reported on 8 March, with ashfall seen on the eastern slopes. A lava dome was observed in Crater Lake on 19 March but was destroyed in a series of explosive eruptions over the following week. A second, larger lava dome appeared in May, which continued to grow over the following months and had emptied Crater Lake of water by July. Eruptions increased from August through November. A particularly powerful eruption in
6888-622: Was set up in November 1926, with 33,516 acres (13,563 ha) set aside for forestry, and taken on by New Zealand Forest Service from 31 March 1927. It stretches about 12 km (7.5 mi) north east from Tangiwai onto the southern slopes of Ruapehu . By March 1931, over 10.7m trees had been planted on 11,650 acres (4,710 ha), for £56,524, 15s 10d. Most of the planting was on land with cobalt deficiency and therefore considered unsuitable for farming, though it also included at least 700 acres (280 ha) of flax . Trees have been harvested since
6972-542: Was spoken by 96.8%, Māori language by 11.5%, Samoan by 0.2% and other languages by 5.0%. No language could be spoken by 2.2% (e.g. too young to talk). New Zealand Sign Language was known by 0.5%. The percentage of people born overseas was 10.9, compared with 28.8% nationally. Religious affiliations were 27.6% Christian , 0.5% Hindu , 0.3% Islam , 5.2% Māori religious beliefs , 0.4% Buddhist , 0.7% New Age , and 1.1% other religions. People who answered that they had no religion were 55.4%, and 9.3% of people did not answer
7056-555: Was that 5,025 (48.8%) people were employed full-time, 1,371 (13.3%) were part-time, and 372 (3.6%) were unemployed. The Ruapehu District Council was established by the 1989 local government reforms . It was formed from the Taumarunui Borough Council, Taumarunui County Council, Waimarino District Council and parts of the Rangitikei County, Taupo District, Waitomo District and Stratford District councils. The council
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