View source for Mount Aso

{{short description|Volcano in Kumamoto Prefecture, Japan}}
{{hatnote|For the city in [[Kumamoto Prefecture]], see [[Aso, Kumamoto]]. For geology and eruptive history see [[Aso Caldera]].}}
{{Infobox mountain
| fetchwikidata = ALL
| name = Mount Aso 
| native_name = 
| native_name_lang = 
| other_name = Aso Volcano
| prominence = 
| prominence_ref = 
| map = Kyushu#Japan Kumamoto Prefecture#Japan
| map_caption = 
| map_size = 280
| label_position = 
| location = [[Kyushu]], Japan
| coordinates = {{coord|32|53|04|N|131|06|14|E|type:mountain_scale:100000|format=dms|display=inline,title}}
| topo = 
| type = [[Somma volcano]] in [[Caldera]] complex
| age = 
| last_eruption = 20 October 2021 - Present
| first_ascent = 
| easiest_route = 
}}

{{nihongo|'''Mount Aso'''|阿蘇山|Aso-san}} or '''[[Aso Caldera|Aso Volcano]]''' is the largest active [[volcano]] in Japan and among the largest in the world. Common use relates often only to the [[somma volcano]] in the centre of [[Aso Caldera]]. It stands in [[Aso Kujū National Park]] in [[Kumamoto Prefecture]], on the island of [[Kyushu]]. Its tallest peak, Takadake, is {{convert|1592|m|sp=us}} above [[sea level]].  Mount Aso is in a fairly large [[caldera]] (25&nbsp;kilometers (16&nbsp;miles) north-south and 18&nbsp;km (11&nbsp;mi) east-west) with a circumference of around {{convert|120|km|mi|abbr=on}}, although sources vary on the exact distance. It is one of the [[100 Famous Japanese Mountains]].

== Geography ==
[[File:Aso Caldera 3D 2012.jpg|thumb|left|[[Aso Caldera]]]]
[[File:Aso Caldera, Central Cone.jpg|thumb|Central Cone]]
[[File:Mount Nakadake from East Hill of Kusasenrigahama.JPG|thumb|Mount Naka (Naka volcano)]]
[[File:Mount-Aso-Naka-dake.jpg|thumb|The steaming crater of Mount Naka]]
{{main|Aso Caldera}}
The central cone group of Aso consists of five peaks, often called the "Five Mountains of Aso" (阿蘇五岳): Mt. Neko, Mt. Taka (also called Takadake or Taka-Dake), Mt. Naka (also called Nakadake or Naka-Dake), Mt. Eboshi, and Mt. Kishima (also called  Kishimadake or Kishima-Dake ). The highest point is the summit of Mt. Taka, at 1,592&nbsp;m above sea level. The crater of Mt. Naka, the west side of which is accessible by road, contains an active volcano which continuously emits smoke and has occasional eruptions. Only the northernmost crater (the first crater) has been active for the last 70 years—1974, 1979, 1984–1985, 1989–1991,<ref name="conference2007">{{cite web|url=http://www.eri.u-tokyo.ac.jp/COV5/main.html|title=Cities on Volcanoes 5|work=u-tokyo.ac.jp}}</ref> 2009, 2011, 2015,<ref>{{cite web|url=http://www.japantimes.co.jp/news/2015/08/08/national/small-volcanic-eruption-recorded-from-mount-aso-in-kumamoto-prefecture|title=Small volcanic eruption recorded from Mount Aso in Kumamoto Prefecture|work=The Japan Times|date=8 August 2015}}</ref> 2016<ref>{{Cite news|url=http://www.japantimes.co.jp/news/2016/04/16/national/small-eruption-seen-on-mount-aso-after-latest-quakes/|title=Small eruption seen on Mount Aso after latest quakes|date=2016-04-16|newspaper=The Japan Times Online|language=en-US|issn=0447-5763|access-date=2016-04-23}}</ref><ref>{{cite news |url=https://www.reuters.com/article/us-japan-volcano-idUSKCN12804E |title=Japan's Mount Aso erupts, no reports of injuries |publisher=Reuters |date=2016-10-07}}</ref> and 2021.<ref>{{cite news |url=https://www.reuters.com/world/asia-pacific/japans-mount-aso-erupts-alert-level-raised-2021-10-20/ |title=Japanese volcano spews plumes of ash, people warned away |publisher=Reuters |date=2021-10-20}}</ref>

The present [[Aso Caldera]] formed as a result of four huge caldera eruptions occurring over a range of 90,000–300,000 years ago.<ref>{{cite web |url=https://volcano.si.edu/volcano.cfm?vn=282110 |title=Global Volcanism Program: Asosan |author=[[Smithsonian Institution]]|date=2013 |url-status=live |archive-url=https://web.archive.org/web/20211021065820/https://volcano.si.edu/ |archive-date=2021-10-21 |access-date=2021-10-21 }}</ref> The caldera, one of the largest in the world, contains the city of [[Aso, Kumamoto|Aso]] as well as [[Takamori, Kumamoto|Takamori]] and [[Minamiaso, Kumamoto|Minamiaso]] enclosing the caldera extends about 18&nbsp;km east to west and about 25&nbsp;km north to south. Viewpoints from the somma overlooking the caldera are perched upon lava formed before the volcanic activity which created the present caldera. [[Ejecta]] from the huge caldera eruption 90,800 years ago covers more than 600&nbsp;km<sup>3</sup> and roughly equals the volume of [[Mount Fuji]]; with a [[pyroclastic flow]] plateau that covered a significant part of Kyushu.

Volcanic ash from Mount Aso and [[Mount Kujū]] plays a crucial role in maintaining and replenishing the [[Mudflat|tidal flat]]s of the [[Ariake Sea]], which are among the largest in Japan. Several of the flats have been designated as [[Ramsar site]]s. The ash is carried from the volcanoes to the coastline by the [[Chikugo River]], which has its source located on Aso as well.<ref>{{Cite web |title=A Theater Company with 3 Players: Ariake Sea Tidal Flats {{!}} People, Wetlands, Wildlife |url=https://pwwj.org/a-theater-company-with-3-players-ariake-sea-tidal-flats/ |access-date=2023-03-04 |language=ja}}</ref>

== History ==
{{main|Aso Caldera}}
The eruption which formed the present [[Somma volcano|somma]] occurred approximately 300,000 years ago. Four large-scale eruptions (Aso 1 – 4) occurred during a period extending from 300,000 to 90,000 years ago. As large amounts of pyroclastic flow and [[volcanic ash]] were emitted from the volcanic chamber, a huge depression (caldera) was formed as the chamber collapsed. The fourth eruption (Aso 4) was the largest, with volcanic ash covering the entire Kyushu region and even extending to [[Yamaguchi Prefecture]].

Mt. Taka, Mt. Naka, Mt. Eboshi, and Mt. Kishima are cones formed following the fourth above-mentioned huge caldera eruption. Mt. Naka remains active today. Aso's pyroclastic flow deposits ([[Tuff#Welded tuff|welded tuff]]) were utilized for bridge construction in the region. There are approximately 320 arched stone bridges in [[Kumamoto Prefecture]], including the [[Tsūjun Bridge|Tsujun-kyo]] and Reitai-kyo bridges on the Midorikawa River, which are [[Important Cultural Property (Japan)|important national cultural properties]].<ref name="conference2007"/>

A new eruption began at 11:43&nbsp;a.m. on 20 October 2021.<ref>{{cite web |title=Mount Aso in Kumamoto erupts |url=https://www3.nhk.or.jp/nhkworld/en/news/20211020_18/ |archive-url=https://web.archive.org/web/20211020032800/https://www3.nhk.or.jp/nhkworld/en/news/20211020_18/ |archive-date=October 20, 2021 |access-date=October 20, 2021 |publisher=nhk.or.jp}}</ref>

==Climate==
With an elevation of {{convert|1143|m|ft}}.,<ref name= NOAA>{{Cite FTP |url = ftp://ftp.atdd.noaa.gov/pub/GCOS/WMO-Normals/RA-II/JP/47821.TXT
  |server = [[National Oceanic and Atmospheric Administration]]
  |title = Asosan Climate Normals 1961-1990
  |access-date = January 6, 2013}}</ref> Mount Aso has a climate that falls as [[humid continental climate|humid continental]] ([[Köppen climate classification]] "''Dfb''"), with warm summers and cold winters. Precipitation is high throughout the year, which brings the area to have borderline [[humid subtropical climate|subtropical]] characteristics as well. It is particularly heavy in June and July, when over {{convert|500|mm|in}} of rain fell in each month.

{{Weather box
|width = auto
|collapsed = yes
|metric first = yes
|single line = yes
|location = Mount Aso, 1991–2020 normals, extremes 1932–2017
|Jan record high C = 14.0
|Feb record high C = 16.6
|Mar record high C = 19.3
|Apr record high C = 23.8
|May record high C = 27.2
|Jun record high C = 27.2
|Jul record high C = 29.6
|Aug record high C = 29.8
|Sep record high C = 28.0
|Oct record high C = 25.1
|Nov record high C = 20.7
|Dec record high C = 15.8
|year record high C = 29.8
|Jan high C = 1.9
|Feb high C = 4.0
|Mar high C = 8.0
|Apr high C = 13.4
|May high C = 17.9
|Jun high C = 20.0
|Jul high C = 23.4
|Aug high C = 24.3
|Sep high C = 21.5
|Oct high C = 16.5
|Nov high C = 10.7
|Dec high C = 4.6
|Jan mean C = −1.4
|Feb mean C = 0.1
|Mar mean C = 3.6
|Apr mean C = 8.9
|May mean C = 13.5
|Jun mean C = 16.7
|Jul mean C = 20.1
|Aug mean C = 20.6
|Sep mean C = 17.7
|Oct mean C = 12.4
|Nov mean C = 6.9
|Dec mean C = 1.0
|Jan low C = -4.5
|Feb low C = -3.6
|Mar low C = -0.3
|Apr low C = 5.0
|May low C = 9.8
|Jun low C = 14.0
|Jul low C = 17.8
|Aug low C = 18.2
|Sep low C = 14.9
|Oct low C = 9.0
|Nov low C = 3.4
|Dec low C = -2.2
|Jan record low C = -15.4
|Feb record low C = -15.9
|Mar record low C = -13.1
|Apr record low C = -7.6
|May record low C = -1.0
|Jun record low C = 5.5
|Jul record low C = 9.8
|Aug record low C = 10.5
|Sep record low C = 4.5
|Oct record low C = -4.0
|Nov record low C = -7.7
|Dec record low C = -13.0
|precipitation colour = green
|Jan precipitation mm = 93.5
|Feb precipitation mm = 132.6
|Mar precipitation mm = 215.7
|Apr precipitation mm = 230.3
|May precipitation mm = 272.6
|Jun precipitation mm = 712.8
|Jul precipitation mm = 634.1
|Aug precipitation mm = 348.4
|Sep precipitation mm = 287.4
|Oct precipitation mm = 133.5
|Nov precipitation mm = 122.4
|Dec precipitation mm = 86.9
|snow colour = green
|Jan snow cm = 26
|Feb snow cm = 21
|Mar snow cm = 9
|Apr snow cm = 1
|May snow cm = 0
|Jun snow cm = 0
|Jul snow cm = 0
|Aug snow cm = 0
|Sep snow cm = 0
|Oct snow cm = 0
|Nov snow cm = 1
|Dec snow cm = 14
|unit precipitation days = 1.0 mm
|Jan precipitation days = 8.9
|Feb precipitation days = 9.4
|Mar precipitation days = 12.4
|Apr precipitation days = 11.5
|May precipitation days = 11.7
|Jun precipitation days = 16.7
|Jul precipitation days = 16.5
|Aug precipitation days = 14.6
|Sep precipitation days = 12.0
|Oct precipitation days = 8.8
|Nov precipitation days = 8.7
|Dec precipitation days = 8.3
|unit snow days = 1 cm
|Jan snow days = 6.1
|Feb snow days = 5.0
|Mar snow days = 1.9
|Apr snow days = 0.2
|May snow days = 0
|Jun snow days = 0
|Jul snow days = 0
|Aug snow days = 0
|Sep snow days = 0
|Oct snow days = 0
|Nov snow days = 0.3
|Dec snow days = 4.1
|Jan humidity = 84
|Feb humidity = 79
|Mar humidity = 76
|Apr humidity = 73
|May humidity = 74
|Jun humidity = 86
|Jul humidity = 90
|Aug humidity = 88
|Sep humidity = 85
|Oct humidity = 80
|Nov humidity = 80
|Dec humidity = 82
|Jan sun = 92.1
|Feb sun = 111.8
|Mar sun = 139.8
|Apr sun = 157.7
|May sun = 168.0
|Jun sun = 100.1
|Jul sun = 114.5
|Aug sun = 131.9
|Sep sun = 127.2
|Oct sun = 148.2
|Nov sun = 120.4
|Dec sun = 107.9
|year sun = 1525.4
|source 1 = [[Japan Meteorological Agency|JMA]]<ref>{{cite web
| url = https://www.data.jma.go.jp/obd/stats/etrn/view/rank_s.php?prec_no=86&block_no=47821&year=&month=4&day=&view=h0
|script-title=ja:観測史上1～10位の値（年間を通じての値）
| publisher = [[Japan Meteorological Agency|JMA]]
| access-date = February 16, 2022}}</ref>
|source 2 = [[Japan Meteorological Agency|JMA]]<ref>{{cite web
| url = https://www.data.jma.go.jp/obd/stats/etrn/view/nml_sfc_ym.php?prec_no=86&block_no=47821&year=&month=4&day=&view=h0
|script-title=ja:気象庁 / 平年値（年・月ごとの値）
| publisher = [[Japan Meteorological Agency|JMA]]
| access-date = February 16, 2022}}</ref>
}}

==National Park==
The mountain is a key feature that contributed to the original [[Aso Kujū National Park|Aso National Park]]. Spectacular sights such as the seasonal flowering of ''[[Rhododendron kiusianum]]'' on the slopes of Takadake reflect significant protected botanical ecosystems.<ref>{{cite web|url=https://www.env.go.jp/en/nature/nps/park/aso/point/index.html|title=Aso-Kuju National Park: Scent of Grasslands, Breath of the Volcanoes, Wind Playing across the Majestic Landscape|access-date=2022-09-28}}</ref>
==Tourism==
[[File:20250710 aso.jpg|thumb|Mount Aso as seen from the volcano museum. ]]Aso has been considered as a sacred place since long time ago. It became a mountain for training and worship. Before the [[Meiji era]], there was only one hiking path from Bauchuu, near the current Aso station.

Foreigners visited Mount Aso for the first time during the Meiji era for tourism and research. A new hiking path from the south of the mountain became famous, as more and more local visitors came.

During the [[Taishō era]], the Miyaji line opened. There were more than 100,000 visitors every year. In 1934, the area was established as [[Aso Kujū National Park|Aso National Park]].

At the foot of the mountain there are also various campsites, and horse riding at Kusasenrigahama.<ref>{{Cite web|url=https://japantravel.navitime.com/en/area/jp/spot/02301-1600310/|title=Aso Kusasenri horseback riding club Details / Explore{{!}} Japan Travel by NAVITIME - Japan Travel Guides, Maps, Transit Search and Route Planner|website=japantravel.navitime.com|access-date=2020-02-14}}</ref> There are also helicopter tours and bicycle tours.

=== Cable car ===
A [[Aerial tramway|cable car]] system, the [[Mount Aso Ropeway]], opened on 10 April 1958 to provide access to the mountain. The system ran for the last time in August 2014, then closed due to higher volcanic alert level. In 2015 and 2016, the system was damaged by volcanic ash and earthquakes. It was totally dismantled in 2019. From February 2018, a shuttle bus runs from the original station, now Mount Aso terminal to the crater's edge .<ref>{{Cite web|url=https://www.kyusanko.co.jp/aso/business/|title=料金・営業案内｜阿蘇山火口シャトル|language=ja|website=www.kyusanko.co.jp|access-date=2023-03-15}}</ref>

=== Onsen ===
Because Mount Aso is a volcano, there are many ''[[onsen]]'' hot springs areas, such as Uchinomaki, Asoakamizu, and Kurokawa.

== Hiking ==
Mt. Aso has numerous hiking trails leading to the interesting peaks and mountains around the crater. The Nakadake trail will take you to the highest peak which is part of the active crater and often closed when volcanic gas or volcanic activity is too high. The other surrounding trails offer enjoyable terrain and unique views over the grasslands, the Aso crater, and a small conical peak called Komezuka. Nearly all of the trails (excluding Nekodake) can be accessed from the bus stop at the museum.

== In popular culture ==
In [[Ishirō Honda]]'s [[Kaiju|kaiju films]], Mount Aso is home to the giant [[pteranodon]] [[kaiju]] [[Rodan]]. In ''[[Rodan (film)|Rodan]]'', the creature and its mate perish when the volcano erupts.<ref>{{Cite web|last=Grebey|first=James|date=May 29, 2019|title=Meet the Monster: The History of Rodan, Godzilla's Greatest Frenemy|url=https://www.syfy.com/syfywire/meet-the-monster-the-history-of-rodan-godzillas-best-frenemy|access-date=April 1, 2021|website=Syfy Wire}}</ref>

Mount Aso serves as the inspiration of Mt. Chimney in ''[[Pokémon Ruby and Sapphire]]'', ''[[Pokémon Emerald]]'' and the remake ''[[Pokémon Omega Ruby and Alpha Sapphire]]''.

In the manga ''[[Magical Girl Spec-Ops Asuka]]'' by [[Makoto Fukami]] and Seigo Tokiya, the final battle of the Distonian War that took place 3 years before the events of the series takes place on Mount Aso.

In the 2006 ''[[tokusatsu]]'' [[disaster film]] ''[[Sinking of Japan]]'' directed by [[Shinji Higuchi]], Mount Aso erupts as an aircraft carrying the [[Japanese Prime Minister]] flies over it, raking the plane with [[tephra|flying rocks]] and causing it to crash with the loss of all on board. Mount Aso's eruption also destroys the city of [[Kumamoto]].

Mount Aso also appears in [[Kaidō Battle 2: Chain Reaction]] and [[Tokyo Xtreme Racer: Drift 2]].

==See also==
{{Portal|Japan|Mountains|Volcanoes|Geography}}
* [[List of volcanoes in Japan]]
* [[Aso Shrine]]
* [[Aso Volcano Museum]]

== References ==
===General===
* {{cite gvp|vn=282110|name=Asosan}}

===Cited===
{{reflist}}

== External links ==
{{commons category|Mount Aso}}
{{wikivoyage|Mount Aso}}
* [http://www.data.jma.go.jp/svd/vois/data/fukuoka/503_Asosan/503_index.html Asosan] - Japan Meteorological Agency {{in lang|ja}}
* [http://www.data.jma.go.jp/svd/vois/data/tokyo/STOCK/souran_eng/volcanoes/084_asosan.pdf Asosan: National catalogue of the active volcanoes in Japan] - Japan Meteorological Agency
* [https://gbank.gsj.jp/volcano/Act_Vol/aso/index-e.html Aso Volcano] - Geological Survey of Japan
* [http://volcano.si.edu/volcano.cfm?vn=282110 Asosan] - Smithsonian Institution: Global Volcanism Program
* [http://www.aso-geopark.jp/en/about/ Aso Geopark]
{{100 Famous Japanese Mountains}}

{{Authority control}}

{{DEFAULTSORT:Aso, Mount}}
[[Category:Volcanoes of Kyushu]]
[[Category:VEI-7 volcanoes]]
[[Category:Active volcanoes]]
[[Category:Subduction volcanoes]]
[[Category:Calderas of Kyushu]]
[[Category:Mountains of Kumamoto Prefecture]]
[[Category:Complex volcanoes]]
[[Category:Volcanoes of Kumamoto Prefecture]]
[[Category:Volcanic eruptions in 2021]]