or Aso Volcano is the largest active

volcano A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most oft ...

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 is a Prefectures of Japan, prefecture of Japan located on the island of Kyūshū. Kumamoto Prefecture has a population of 1,748,134 () and has a geographic area of . Kumamoto Prefecture borders Fukuoka Prefecture to the north, Ōita Prefecture t ...

, on the island of

Kyushu is the third-largest island of Japan's Japanese archipelago, four main islands and the most southerly of the four largest islands (i.e. excluding Okinawa Island, Okinawa and the other Ryukyu Islands, Ryukyu (''Nansei'') Ryukyu Islands, Islands ...

. Its tallest peak, Takadake, is above

sea level Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical ...

. Mount Aso is in a fairly large

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

(25 kilometers (16 miles) north-south and 18 km (11 mi) east-west) with a circumference of around , although sources vary on the exact distance. It is one of the

100 Famous Japanese Mountains is a book written in 1964 by Mountaineering, mountaineer and author Kyūya Fukada.Hyakumeizan, Hiking Japan ...

Geography

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 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, 2009, 2011, 2015, 2016 and 2021. The present Aso Caldera formed as a result of four huge caldera eruptions occurring over a range of 90,000–300,000 years ago. The caldera, one of the largest in the world, contains the city of Aso as well as Takamori and Minamiaso enclosing the caldera extends about 18 km east to west and about 25 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 Ejecta (; ) are particles ejected from an area. In volcanology, in particular, the term refers to particles including pyroclastic rock, pyroclastic materials (tephra) that came out of a explosive eruption, volcanic explosion and magma eruption v ...

from the huge caldera eruption 90,800 years ago covers more than 600 km³ and roughly equals the volume of

Mount Fuji is an active stratovolcano located on the Japanese island of Honshu, with a summit elevation of . It is the highest mountain in Japan, the second-highest volcano on any Asian island (after Mount Kerinci on the Indonesian island of Sumatra), a ...

; with a

pyroclastic flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average speeds of b ...

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

tidal flat Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal ...

s of the

Ariake Sea The is a body of salt water surrounded by Fukuoka, Saga, Nagasaki, and Kumamoto Prefectures, all of which lie on the island of Kyūshū in Japan. It is the largest bay in Kyūshū. Its deepest point is only about 50 meters (165 ft) deep, and ext ...

, which are among the largest in Japan. Several of the flats have been designated as

Ramsar site A Ramsar site is a wetland site designated to be of international importance under the Ramsar Convention,8 ha (O) *** Permanent 8 ha (P) *** Seasonal Intermittent < 8 ha(Ts) **

Chikugo River, which has its source located on Aso as well.

History

The eruption which formed the present 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 Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, produced during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to r ...

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 is a Prefectures of Japan, prefecture of Japan located in the Chūgoku region of Honshu. Yamaguchi Prefecture has a population of 1,377,631 (1 February 2018) and has a geographic area of 6,112 Square kilometre, km2 (2,359 Square mile, sq mi). ...

. 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 ( welded tuff) were utilized for bridge construction in the region. There are approximately 320 arched stone bridges in

, including the Tsujun-kyo and Reitai-kyo bridges on the Midorikawa River, which are important national cultural properties. A new eruption began at 11:43 a.m. on 20 October 2021.

Climate

With an elevation of ., Mount Aso has a climate that falls as humid continental (

Köppen climate classification The Köppen climate classification divides Earth climates into five main climate groups, with each group being divided based on patterns of seasonal precipitation and temperature. The five main groups are ''A'' (tropical), ''B'' (arid), ''C'' (te ...

"''Dfb''"), with warm summers and cold winters. Precipitation is high throughout the year, which brings the area to have borderline

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...

characteristics as well. It is particularly heavy in June and July, when over of rain fell in each month.

National Park

The mountain is a key feature that contributed to the original Aso National Park. Spectacular sights such as the seasonal flowering of ''

Rhododendron kiusianum ''Rhododendron kiusianum'', the Kyushu azalea, is a species of flowering plant in the family Ericaceae, native to Kyushu, Japan. It is a parent of a large number of hybrid dwarf azaleas, drawn from the naturally-occurring Kurume azaleas used in ...

'' on the slopes of Takadake reflect significant protected botanical ecosystems.

Tourism

Aso has been considered as a sacred place since long time ago. It became a mountain for training and worship. Before the

Meiji era The was an Japanese era name, era of History of Japan, Japanese history that extended from October 23, 1868, to July 30, 1912. The Meiji era was the first half of the Empire of Japan, when the Japanese people moved from being an isolated feu ...

, 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 was a period in the history of Japan dating from 30 July 1912 to 25 December 1926, coinciding with the reign of Emperor Taishō. The new emperor was a sickly man, which prompted the shift in political power from the old oligarchic group ...

, the Miyaji line opened. There were more than 100,000 visitors every year. In 1934, the area was established as Aso National Park. At the foot of the mountain there are also various campsites, and horse riding at Kusasenrigahama. There are also helicopter tours and bicycle tours.

Cable car

A 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 .

Onsen

Because Mount Aso is a volcano, there are many ''

onsen In Japan, are hot springs and the bathing facilities and Ryokan (inn), traditional inns around them. There are approximately 25,000 hot spring sources throughout Japan, and approximately 3,000 ''onsen'' establishments use naturally hot water ...

'' 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

Ishirō Honda was a Japanese filmmaker who directed 46 feature films in a career spanning five decades. He is acknowledged as the most internationally successful Japanese filmmaker prior to Hayao Miyazaki and one of the founders of modern disaster film, wit ...

's kaiju films, Mount Aso is home to the giant

pteranodon ''Pteranodon'' (; from and ) is a genus of pterosaur that included some of the largest known flying reptiles, with ''P. longiceps'' having a wingspan of over . They lived during the late Cretaceous geological period of North America in presen ...

creature Rodan. In '' Rodan'', the creature and its mate perish in the volcano's eruption. 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 is a Japanese term for live-action films or television programs that make heavy use of practical special effects. Credited to special effects director Eiji Tsuburaya, ''tokusatsu'' mainly refers to science fiction film, science fiction, War fi ...

disaster film A disaster film or disaster movie is a film genre that has an impending or ongoing disaster as its subject and primary plot device. Such disasters may include natural disasters, accidents, offensive (military), military/terrorism, terrorist att ...

'' 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 flying rocks and causing it to crash with the loss of all on board. Mount Aso's eruption also destroys the city of

Kumamoto is the capital Cities of Japan, city of Kumamoto Prefecture on the island of Kyushu, Japan. , the city has an estimated population of 738,907 and a population density of 1,893 people per km2. The total area is 390.32 km2. had a populat ...

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

References

General

Cited

External links

Asosan
- Japan Meteorological Agency
Asosan: National catalogue of the active volcanoes in Japan
- Japan Meteorological Agency

- Geological Survey of Japan
Asosan
- Smithsonian Institution: Global Volcanism Program
Aso Geopark
{{DEFAULTSORT:Aso, Mount Volcanoes of Kyushu VEI-7 volcanoes Active volcanoes Subduction volcanoes Calderas of Kyushu Mountains of Kumamoto Prefecture Complex volcanoes Volcanoes of Kumamoto Prefecture Volcanic eruptions in 2021