is an active

complex volcano A complex volcano, also called a compound volcano or a volcanic complex, is a mixed landform consisting of related volcanic centers and their associated lava flows and pyroclastic rock. They may form due to changes in eruptive habit or in t ...

in central

Honshū , historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island separa ...

, the main island of

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

. The volcano is the most active on Honshū. The

Japan Meteorological Agency The , abbreviated JMA, is an agency of the Ministry of Land, Infrastructure, Transport and Tourism. It is charged with gathering and providing results for the public in Japan that are obtained from data based on daily scientific observation an ...

classifies Mount Asama as rank A. It stands above

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

on the border of

Gunma is a prefecture of Japan located in the Kantō region of Honshu. Gunma Prefecture has a population of 1,937,626 (1 October 2019) and has a geographic area of 6,362 km2 (2,456 sq mi). Gunma Prefecture borders Niigata Prefecture and Fukushima P ...

and

Nagano prefecture is a landlocked prefecture of Japan located in the Chūbu region of Honshū. Nagano Prefecture has a population of 2,052,493 () and has a geographic area of . Nagano Prefecture borders Niigata Prefecture to the north, Gunma Prefecture to the ...

s. It is included in ''

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

''.

Geology

Mount Asama sits at the conjunction of the

Izu–Bonin–Mariana Arc The Izu–Bonin–Mariana (IBM) arc system is a plate tectonics, tectonic plate convergent boundary in Micronesia. The IBM arc system extends over 2800 km south from Tokyo, Japan, to beyond Guam, and includes the Izu Islands, the Bonin Island ...

and the Northeastern Japan Arc. The mountain is built up from non-alkali mafic and pyroclastic volcanic rocks dating from the

Late Pleistocene The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division of ...

to the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...

. The main rock types are

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomi ...

and

dacite Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...

Scientists from the

University of Tokyo , abbreviated as or UTokyo, is a public research university located in Bunkyō, Tokyo, Japan. Established in 1877, the university was the first Imperial University and is currently a Top Type university of the Top Global University Project by ...

and

Nagoya University , abbreviated to or NU, is a Japanese national research university located in Chikusa-ku, Nagoya. It was the seventh Imperial University in Japan, one of the first five Designated National University and selected as a Top Type university of T ...

completed their first successful imaging experiment of the interior of the volcano in April 2007. By detecting sub-atomic particles called

muons A muon ( ; from the Greek letter mu (μ) used to represent it) is an elementary particle similar to the electron, with an electric charge of −1 '' e'' and a spin of , but with a much greater mass. It is classified as a lepton. As wi ...

as they passed through the volcano after arriving from space, the scientists were able gradually to build up a picture of the interior, creating images of cavities through which lava was passing deep inside the volcano. A University of Tokyo

volcano observatory A volcano observatory is an institution that conducts research and monitoring of a volcano. Each observatory provides continuous and periodic monitoring of the Seismology, seismicity, other geophysical changes, ground movements, volcanic gas chemis ...

is located on the mountain's east slope. Volcanic gas emissions from this volcano are measured by a Multi-Component Gas Analyzer System, which detects pre-eruptive degassing of rising magmas, improving

prediction of volcanic activity Prediction of volcanic activity, or volcanic eruption forecasting, is an interdisciplinary monitoring and research effort to predict the time and severity of a volcano's eruption. Of particular importance is the prediction of hazardous eruptions t ...

. There is also another mountain called Asama (朝熊山, ''Asama-yama'') of only 555 meters in

Mie Prefecture is a prefecture of Japan located in the Kansai region of Honshu. Mie Prefecture has a population of 1,781,948 () and has a geographic area of . Mie Prefecture is bordered by Gifu Prefecture to the north, Shiga Prefecture and Kyoto Prefecture to ...

Eruptive history

The geologic features of this active volcano are closely monitored with

seismograph A seismometer is an instrument that responds to ground noises and shaking such as caused by earthquakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The output ...

s and strategically positioned video cameras. VolcanoLive.com
/ref> Scientists have noted a range of textural variety in the ash which has been deposited in the region during the serial eruptions since the ''Tennin'' eruption of 1108.

''Tennin'' eruption (1108)

The eruption of Mount Asama in 1108 (''

Tennin , which may include , , and the specifically female version, the , are a divine kind of spiritual beings found in Buddhism in Japan, Japanese Buddhism, the equivalent of Angels. They were seemingly imported from Chinese Buddhism,''Tenmei'' catastrophe in 1783. A Swiss research team found Mount Asama's volcanic eruption could have contributed to extreme weather that caused severe famine, torrential rain and consecutive cold summers in Europe. They studied ice cores in

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...

which had increased sulfate deposition in 1108 CE. In the late

Heian Period The is the last division of classical Japanese history, running from 794 to 1185. It followed the Nara period, beginning when the 50th emperor, Emperor Kanmu, moved the capital of Japan to Heian-kyō (modern Kyoto). means "peace" in Japanese. ...

(794–1185) the diary of the court noble

Fujiwara no Munetada Fujiwara (, written: 藤原 lit. "''Wisteria'' field") is a Japanese surname. (In English conversation it is likely to be rendered as .) Notable people with the surname include: ; Families * The Fujiwara clan and its members ** Fujiwara no Kamatari ...

reported that Mount Asama erupted on 29 August 1108. He wrote that a local report described rice paddies and fields could not be farmed due to being covered by a thick layer of ash.

''Tenmei'' eruption (1783)

Mount Asama erupted in 1783 (''

Tenmei is a Japanese era name (年号, ''nengō'', literally "years name") for the years between the An'ei Era and before the Kansei Era, from April 1781 through January 1789. The reigning emperor was . Change of era * 1781 : The new era name of Tenme ...

3''), causing widespread damage. The three-month-long plinian eruption that began on 9 May 1783, produced

andesitic Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...

pumice falls,

pyroclastic Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroc ...

flows, lava flows, and enlarged the cone. The climactic eruption began on 4 August and lasted for 15 hours, and contained pumice falls and pyroclastic flows. The complex features of this eruption are explained by rapid deposits of coarse pyroclastic ash near the vent and the subsequent flows of lava; and these events which were accompanied by a high

eruption plume An eruption column or eruption plume is a cloud of super-heated ash and tephra suspended in gases emitted during an explosive volcanic eruption. The volcanic materials form a vertical column or plume that may rise many kilometers into the air a ...

which generated further injections of pumice into the air.

1982 eruption

Explosive eruptions occurred at the summit of Asama volcano on 26 April. Fine ash fell in Tokyo, to the SE, for the first time in 23 years.

1983 eruptions

An explosive eruption occurred on 8 April. Incandescent tephra was ejected, and ash fell from the volcano.

1995 earthquakes

In April 1995, more than 1000 earthquakes were detected at the volcanic mountain.

2004 eruption

A single vulcanian eruption occurred at Asama volcano at 11:02 UT on 1 September 2004. Incandescent blocks were ejected from the summit and caused many fires. The eruption sent ash and rock as far away as .

2008 eruptions

Three small ash eruptions occurred at Asama volcano in August 2008. This was the first activity at the volcano since 2004.

2009 eruptions

Mount Asama erupted in early February 2009, sending ash to a height of ,"Volcano erupts close to Tokyo,"
BBC. 2 February 2009. and throwing rocks up to from the crater. Ash fall was reported in Tokyo, southeast of the volcano crater. On 16 February there were 13 recorded volcanic earthquakes and an eruption emitting smoke and ash in a cloud high. Mount Asama continued to have small eruptions, tremors and earthquakes in February and remained on level-3 alert, with a danger zone within of the crater.
18 February 2009.

Marking the span of Japan's history

The eruptions of Mount Asama mark the span of Japan's recorded history, including: 2019, ''2009'', ''2008'', ''2004'', 2003, ''1995'', 1990, ''1983'', ''1982'', 1973, 1965, 1961, 1958–59, 1953–55, 1952, 1952, 1950–51, 1949, 1947, 1946, 1944–45, 1938–42, 1935–37, 1934, 1934, 1933, 1931–32, 1930, 1929, 1929, 1927–28, 1924, 1922, 1920–21, 1919, 1918?, 1917, 1916, 1915, 1914, 1909–14, 1908, 1908, 1907, 1907, 1906, 1905?, 1904, 1903, 1902, 1902, 1900–01, 1899, 1899, 1894, 1889, 1879, 1878?, 1875, 1869, 1815, 1803, 1803, ''1783'', 1779?, 1777, 1776, 1769, 1762, 1755, 1754, 1733, 1732, 1731, 1729, 1729, 1728, 1723, 1723, 1722, 1721, 1720, 1719, 1718, 1717, 1711, 1710, 1708–09, 1706, 1704, 1703, 1669, 1661, 1661, 1660, 1659, 1658, 1657, 1656, 1655, 1653, 1652, 1651, 1650?, 1649, 1648, 1648, 1647, 1645, 1644, 1609, 1605, 1604, 1600, 1598, 1597, 1596, 1596, 1595?, 1591, 1590, 1532, 1528, 1527, 1518, 1427?, 1281, ''1108'', 887, 685. Note: The dates of eruptions featured in this article appear in bold italics.

Onioshidashi

Onioshidashi () "expelling demons" is the name of a

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or und ...

on the northern slope of Mount Asama. The lava flow that erupted in 1783

Tenmei eruption The Tenmei eruption () was a large eruption of Mount Asama that occurred in 1783 (''Tenmei 3''). This eruption was one of the causes of the Tenmei famine. It is estimated that about 1,500–1,624 people were killed in the eruption. The event is k ...

was solidified. Now, it is known as a tourist destination.

Asama Volcano Museum

The Asama Volcano Museum (), from the crater of the Mount Asama,浅間火山博物館閉館へ
『読売新聞』(''

Yomiuri Shimbun The (lit. ''Reading-selling Newspaper'' or ''Selling by Reading Newspaper'') is a Japanese newspaper published in Tokyo, Osaka, Fukuoka, and other major Japanese cities. It is one of the five major newspapers in Japan; the other four are t ...

''), 8 August 2020. Accessed 1 July 2021. open from 1993 to 2020, explained volcanoes. The museum was in Naganohara-machi, Agatsuma-gun,

Gunma Prefecture is a prefecture of Japan located in the Kantō region of Honshu. Gunma Prefecture has a population of 1,937,626 (1 October 2019) and has a geographic area of 6,362 km2 (2,456 sq mi). Gunma Prefecture borders Niigata Prefecture and Fukushima ...

. As of early 2009, it was open from April until November. Visitor numbers peaked at 265,000 in 1994; however, seismic activity at nearby Mount Asama was one reason for frequent closures. The closures were a factor in the drop in visitors:浅間火山博物館を閉館　年度内に長野原町　新型コロナで休館中
『上毛新聞』 ('' Jōmō Shinbun''), 9 August 2020. Accessed 1 July 2021. this gradually fell to 23,000. In the later years of the museum, most of the visitors were on school excursions. The museum was running a deficit of about 17 million yen per year, paid for by the town of Naganohara. Additionally, the building was ageing, and maintenance threatened to cost hundreds of millions of yen. A nearby building, Asama memorial hall () exhibited motorbikes; the plan in summer 2020 was to move these to a municipally owned tourist facility, Asama pasture (), and to move some of the exhibits of the volcano museum to the memorial hall.

Gallery

File:Mt.Asama2 (From saku city).jpg, Viewed from the south File:220929 Mt Asama Karuizawa Nagano pref Japan01s3.jpg, Viewed from the southeast File:Mt asama.jpg, Viewed from the SSE File:Mt.Asama (From onioshidashi).jpg, Viewed from the north File:Kisokaido03 Urawa.jpg,

Hiroshige Utagawa Hiroshige (, also ; ja, 歌川広重 ), born Andō Tokutarō (; 1797 – 12 October 1858), was a Japanese ''ukiyo-e'' artist, considered the last great master of that tradition. Hiroshige is best known for his horizontal-format l ...

In popular culture

Mount Asama served as the backdrop to Japan's first colour film, ''

Carmen Comes Home is a 1951 Japanese comedy film directed by Keisuke Kinoshita. It was Japan's first feature length colour film. Plot Due to the renovation of the Tokyo based venue where she works, Okin, stage name Lily Carmen, and her lovesick friend Maya pay her ...

''. Several references are made to Mount Asama throughout the film, including a melody composed by a blind composer, Mr. Taguchi. In the anime ''

Neon Genesis Evangelion , also known simply as ''Evangelion'' or ''Eva'', is a Japanese mecha anime television series produced by Gainax and animated by Tatsunoko, directed by Hideaki Anno and broadcast on TV Tokyo from October 1995 to March 1996. ''Evangelion' ...

'', the Eighth Angel, Sandalphon, was located inside Mount Asama.

Notes

References

* Hall, John Whitney (1955). ''

Tanuma Okitsugu (September 11, 1719, in Edo, Japan – August 25, 1788, in Edo) was a chamberlain (''sobashū'') and a senior counselor (''rōjū'') to the ''shōgun'' Tokugawa Ieharu of the Tokugawa Shogunate, in the Edo period of Japan. Tanuma and his s ...

, 1719–1788: Forerunner of Modern Japan, '' Cambridge:

Harvard University Press Harvard University Press (HUP) is a publishing house established on January 13, 1913, as a division of Harvard University, and focused on academic publishing. It is a member of the Association of American University Presses. After the retirem ...

. *Hayakawa, Yukio and Hideko Nakajima
"Volcanic Eruptions and Hazards of Asama Written in Historical Records" (abstract)
''Bulletin of the Volcanological Society of Japan'' (''

Kazan Kazan ( ; rus, Казань, p=kɐˈzanʲ; tt-Cyrl, Казан, ''Qazan'', IPA: ɑzan is the capital and largest city of the Republic of Tatarstan in Russia. The city lies at the confluence of the Volga and the Kazanka rivers, covering a ...

''). 19 July 2006. * Screech, Timon (2006)
''Secret Memoirs of the Shoguns: Isaac Titsingh and Japan, 1779–1822.''
London:

RoutledgeCurzon Routledge () is a British multinational publisher. It was founded in 1836 by George Routledge, and specialises in providing academic books, journals and online resources in the fields of the humanities, behavioural science, education, law, and ...

. (cloth); (electronic) * Titsingh, Isaac (1834). iyun-sai Rin-siyo/Hayashi Gahō, 1652">Hayashi_Gahō.html" ;"title="iyun-sai Rin-siyo/ iyun-sai Rin-siyo/Hayashi Gahō, 1652 ''Nipon o daï itsi ran">Hayashi Gahō">iyun-sai Rin-siyo/Hayashi Gahō, 1652">Hayashi_Gahō.html" ;"title="iyun-sai Rin-siyo/Hayashi Gahō">iyun-sai Rin-siyo/Hayashi Gahō, 1652 ''Nipon o daï itsi ran; ou
Annales des empereurs du Japon.
' Paris: Royal Asiatic Society">Oriental Translation Fund of Great Britain and Ireland.

External links

Asamayama
– Japan Meteorological Agency * – Japan Meteorological Agency

– Geological Survey of Japan
Asamayama
– Smithsonian Institution: Global Volcanism Program {{DEFAULTSORT:Asama Mountains of Gunma Prefecture Mountains of Nagano Prefecture Volcanoes of Honshū Subduction volcanoes Active volcanoes VEI-5 volcanoes Complex volcanoes 18th-century volcanic events Volcanoes of Gunma Prefecture Volcanoes of Nagano Prefecture Highest points of Japanese national parks Calderas of Honshū