Editing Mount Ruapehu (section)

==Geography==

Ruapehu is located in the centre of the [[North Island]] of New Zealand, {{cvt|23|km|mi|0}} northeast of [[Ohakune]], [[New Zealand]] and {{cvt|23|km|mi|0}} 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&nbsp;km<sup>3</sup>.<ref name="Hackett1985" /> The volcano is surrounded by a ring plain of volcanic material, made from [[lahar]] deposits, ash fall, and [[volcanic landslide|landslide]] debris.<ref name="GNS Ruapehu">{{cite web |title=Ruapehu / New Zealand Volcanoes / Volcanoes / Science Topics / Learning / Home – GNS Science |url=https://www.gns.cri.nz/Home/Learning/Science-Topics/Volcanoes/New-Zealand-Volcanoes/Ruapehu |website=www.gns.cri.nz |access-date=3 February 2021 |archive-date=2 July 2022 |archive-url=https://web.archive.org/web/20220702114317/https://www.gns.cri.nz/Home/Learning/Science-Topics/Volcanoes/New-Zealand-Volcanoes/Ruapehu |url-status=live }}</ref>

There are three access routes to Ruapehu, and each access route leads to one of the three skifields that are found on its slopes. [[State Highway 48 (New Zealand)|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|Turoa skifield]] on the southwestern slopes, and a [[four-wheel drive]] track leads from the Desert Road ([[State Highway 1 (New Zealand)|State Highway 1]]) to the [[Tukino|Tukino skifield]] on the eastern slopes.<ref>{{cite web |title=How to get to Tukino – Tukino Skifield – Mt Ruapehu, NZ |url=https://www.tukino.org/how-to-get-to-tukino-ski-field |website=Tukino Skifield |language=en-NZ |access-date=29 March 2021 |archive-date=9 February 2021 |archive-url=https://web.archive.org/web/20210209031844/https://www.tukino.org/how-to-get-to-tukino-ski-field |url-status=live }}</ref><ref name="DOC Getting">{{cite web |title=Getting there |url=https://www.doc.govt.nz/parks-and-recreation/places-to-go/central-north-island/places/tongariro-national-park/things-to-do/tracks/round-the-mountain-track/getting-there/ |website=[[Department of Conservation (New Zealand)|Department of Conservation]] |access-date=5 February 2021 |language=en-nz |archive-date=25 October 2021 |archive-url=https://web.archive.org/web/20211025073748/https://www.doc.govt.nz/parks-and-recreation/places-to-go/central-north-island/places/tongariro-national-park/things-to-do/tracks/round-the-mountain-track/getting-there/ |url-status=live }}</ref>

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 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.<ref name="Purves 1990" /><ref name="Keys 2007" />

===Glaciers===

A total of 18 [[glacier]]s have been recognised on Ruapehu, of which six are named.<ref name="Chinn 2001">{{cite journal |last1=Chinn |first1=T. J. |title=Distribution of the Glacial Water Resources of New Zealand |journal=Journal of Hydrology (New Zealand) |date=2001 |volume=40 |issue=2 |pages=139–187 |jstor=43922047 |url=https://www.jstor.org/stable/43922047 |access-date=2 February 2021 |archive-date=30 October 2020 |archive-url=https://web.archive.org/web/20201030001642/https://www.jstor.org/stable/43922047 |url-status=live }}</ref> Two glaciers are found in 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.<ref name="Keys 1988" /> Most of the ice on Ruapehu is contained in only three of its glaciers: the Whangaehu, Summit Plateau, and Mangatoetoenui glaciers.<ref name="Chinn 2001" /> The Summit Plateau glacier is not a glacier in the true sense, but rather an ice field that fills an extinct volcanic crater, and the ice there reaches more than 130&nbsp;m thick.<ref name="Keys 1988" /> 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.<ref name="Keys 1988" /><ref name="Miles 1984">{{cite book |last1=Miles |first1=Sue |title=The River : the story of the Waikato |date=1984 |publisher=Heinemann |location=Auckland, N.Z. |isbn=978-0-86863-418-0}}</ref> On the western side of the mountain, many of the streams that arise there, such as the [[Whakapapa River|Whakapapa]] and [[Manganui o te Ao River|Manganui o te Ao]] rivers, feed the [[Whanganui River]].<ref>{{cite map |author=Land Information New Zealand |author-link=Land Information New Zealand |year=2020 |title=NZ Topo50 |type=Topographic map |scale=1:50,000 |publisher=Land Information New Zealand}}</ref>

[[File:MountRuapehu.jpg|thumb|300px|Mount Ruapehu, January 2002.]]
Ruapehu's glaciers are situated at 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.<ref name="Keys 1988">{{cite journal |last1=Keys |first1=H. |title=1988 Survey of the Glaciers on Mt Ruapehu, Tongariro National Park – A Baseline for Detecting Threats of Climate Change |journal=Department of Conservation Science and Research Internal Report 24 (Unpublished) |date=1988 |url=https://www.doc.govt.nz/globalassets/documents/science-and-technical/srir24.pdf |access-date=2 February 2021 |archive-date=25 October 2021 |archive-url=https://web.archive.org/web/20211025071106/https://www.doc.govt.nz/globalassets/documents/science-and-technical/srir24.pdf |url-status=live }}</ref><ref name="Odell 1955">{{cite journal |last1=Odell |first1=N. E. |title=Mount Ruapehu, New Zealand: Observations on its Crater Lake and Glaciers |journal=Journal of Glaciology |date=1955 |volume=2 |issue=18 |pages=601–605 |doi=10.3189/002214355793702181|bibcode=1955JGlac...2..601O |doi-access=free}}</ref>

===Climate===

Ruapehu has a [[Polar climate#Subtypes|polar tundra]] climate ([[Köppen climate classification|Köppen]]: ''ET'') on the upper slopes, with average temperatures ranging from −4–15&nbsp;°C in summer and −7–7&nbsp;°C in winter, depending on elevation and cloudiness.<ref name="Beck 2018 Koppen">{{cite journal |last1=Beck |first1=Hylke E. |last2=Zimmermann |first2=Niklaus E. |last3=McVicar |first3=Tim R. |last4=Vergopolan |first4=Noemi |last5=Berg |first5=Alexis |author6-link=Eric Franklin Wood |last6=Wood |first6=Eric F. |title=Present and future Köppen-Geiger climate classification maps at 1-km resolution |journal=Scientific Data |date=18 December 2018 |volume=5 |issue=1 |pages=180214 |doi=10.1038/sdata.2018.214 |pmid=30375988 |pmc=6207062 |bibcode=2018NatSD...580214B |doi-access=free}}</ref><ref name="Thompson 1984">{{cite journal |last1=Thompson |first1=C. S. |title=The weather and climate of the Tongariro region |journal=New Zealand Meteorological Service Miscellaneous Publication 115(14) |date=1984}}</ref> On the lower slopes, Ruapehu has a [[Temperate climate#Subpolar oceanic (Cfc, Cwc, Csc)|subpolar oceanic climate]] (Köppen: ''Cfc'').<ref name="Beck 2018 Koppen" />

The prevalent wind direction in the region is westerly or northwesterly, and gale force conditions (i.e. wind speeds higher than {{cvt|33|knots|km/h}}) are common on the mountain.<ref name="Thompson 1984" /> 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&nbsp;mm of rain per year, whereas the [[Rangipo Desert]] to the east of Ruapehu receives slightly more than 1,500&nbsp;mm of rain annually.<ref name="DOC Weather">{{cite web |title=Tongariro weather |url=https://www.doc.govt.nz/parks-and-recreation/places-to-go/central-north-island/places/tongariro-national-park/about-tongariro-national-park/tongariro-weather/ |website=[[Department of Conservation (New Zealand)|Department of Conservation]] |language=en-nz |access-date=29 March 2021 |archive-date=22 February 2021 |archive-url=https://web.archive.org/web/20210222223030/https://www.doc.govt.nz/parks-and-recreation/places-to-go/central-north-island/places/tongariro-national-park/about-tongariro-national-park/tongariro-weather/ |url-status=live }}</ref> Snow falls on average as low as 1,500&nbsp;m elevation.<ref name="DOC Weather" />

{{Weather box|width=auto
|metric first=y
|single line=y 
|collapsed = Y
|location = Mount Ruapehu (Whakapapa Village), elevation {{convert|1097|m|ft|abbr=on}}, (1991–2020)
|Jan high C = 	18.3
|Feb high C = 	18.2
|Mar high C = 	16.2
|Apr high C = 	13.0
|May high C = 	10.0
|Jun high C = 	7.5
|Jul high C = 	6.9
|Aug high C = 	7.3
|Sep high C = 	9.1
|Oct high C = 	11.0
|Nov high C = 	13.6
|Dec high C = 	15.9
| year high C = 	
|Jan mean C = 	12.5
|Feb mean C = 	12.8
|Mar mean C = 	11.0
|Apr mean C = 	8.5
|May mean C = 	6.1
|Jun mean C = 	3.8
|Jul mean C = 	3.2
|Aug mean C = 	3.5
|Sep mean C = 	4.9
|Oct mean C = 	6.5
|Nov mean C = 	8.4
|Dec mean C = 	10.9
| year mean C = 	
|Jan low C = 	6.7
|Feb low C = 	7.4
|Mar low C = 	5.8
|Apr low C = 	4.0
|May low C = 	2.1
|Jun low C = 	0.1
|Jul low C = 	-0.6
|Aug low C = 	-0.4
|Sep low C = 	0.7
|Oct low C = 	1.9
|Nov low C = 	3.1
|Dec low C = 	5.8
| year low C = 	
|rain colour = green	
|Jan rain mm = 	171.9
|Feb rain mm = 	156.9
|Mar rain mm = 	161.1
|Apr rain mm = 	204.5
|May rain mm = 	253.7
|Jun rain mm = 	271.9
|Jul rain mm = 	280.2
|Aug rain mm = 	259.3
|Sep rain mm = 	283.0
|Oct rain mm = 	276.9
|Nov rain mm = 	245.5
|Dec rain mm = 	245.1
|year rain mm = 	
|source 1 = NIWA<ref name= NIWA>
{{cite web
|url = http://cliflo.niwa.co.nz
|title = CliFlo – National Climate Database : Mt Ruapehu, Chateau Ews	
|publisher = NIWA
|access-date = 20 May 2024}}</ref>
}}

===Severe weather incidents===

Weather conditions can be changeable over the day, and mountain visitors are advised to be prepared and carry basic survival equipment.<ref name="DOC Weather 2">{{cite web |title=Round the Mountain Track |url=https://www.doc.govt.nz/parks-and-recreation/places-to-go/central-north-island/places/tongariro-national-park/things-to-do/tracks/round-the-mountain-track/#Weather |website=[[Department of Conservation (New Zealand)|Department of Conservation]] |access-date=15 March 2021 |language=en-nz |archive-date=28 March 2021 |archive-url=https://web.archive.org/web/20210328213652/https://www.doc.govt.nz/parks-and-recreation/places-to-go/central-north-island/places/tongariro-national-park/things-to-do/tracks/round-the-mountain-track/#Weather |url-status=live }}</ref> 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.<ref>{{cite web |url=http://www.dpmc.govt.nz/honours/lists/list.asp?id=18 |title=Special Honours List 1999 |publisher=New Zealand Government |date=23 October 1999 |access-date=2009-02-11 |archive-date=5 February 2009 |archive-url=https://web.archive.org/web/20090205035002/http://dpmc.govt.nz/honours/lists/list.asp?id=18 |url-status=live }}</ref> The same storm also trapped an experienced Japanese mountaineer when the weather unexpectedly closed in on him, but he built a [[snow cave]] and sheltered in it until he was rescued days later.<ref name=upi_19900816/>

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.<ref>{{cite news|last=Charman |first=Paul |date=6 June 2014 |title=Outdoors: Preparing the snow |url=http://www.nzherald.co.nz/sport/news/article.cfm?c_id=4&objectid=11268723 |work=[[The New Zealand Herald]] |access-date=11 November 2016 |archive-date=12 November 2016 |archive-url=https://web.archive.org/web/20161112082303/http://www.nzherald.co.nz/sport/news/article.cfm?c_id=4&objectid=11268723 |url-status=live }}</ref> In 2008 extreme weather resulted in about 2000 visitors being evacuated from Whakapapa skifield, with cars being led down the mountain in groups of five. About 100 cars were left at the skifield overnight.<ref>{{Cite news|archive-url=https://web.archive.org/web/20080925082155/http://www.stuff.co.nz/4631448a11.html|archive-date=2008-09-25|url-status=live |url=http://www.stuff.co.nz/4631448a11.html |title=Northland cops it as storm sweeps island |publisher=[[Fairfax New Zealand]] |date=26 July 2008}}</ref><ref>{{cite web |title=July 2008 North Island Weather Bomb ( 2008-07-26 ) |url=https://hwe.niwa.co.nz/event/July_2008_North_Island_Weather_Bomb |website=hwe.niwa.co.nz |access-date=15 March 2021 |archive-date=29 January 2021 |archive-url=https://web.archive.org/web/20210129151205/https://hwe.niwa.co.nz/event/July_2008_North_Island_Weather_Bomb |url-status=live }}</ref>