View source for Mount Asama

{{Short description|Volcano on the island of Honshū, Japan}}
{{Use dmy dates|date=August 2020}}
{{Infobox mountain
| name = Mount Asama
| native_name ={{native name|ja|浅間山}}
| photo = Mount Asama.JPG
| photo_caption = Viewed from the East
| elevation_m = 2568
| elevation_ref = 
| prominence_m = 1271
| prominence_ref = <ref>{{cite web | url=https://worldribus.org/japanese-archipelago/ | title=Japanese Archipelago - World Ribus | date=25 February 2023 }}</ref>
| listing = [[List of mountains and hills of Japan by height]]<br />[[List of the 100 famous mountains in Japan|100 famous mountains in Japan]]<br />[[List of volcanoes in Japan]]<br />Ribu
| location = [[Honshū]], Japan
| range = 
| map = Japan#Japan Gunma Prefecture
| coordinates = {{coord|36|24|23|N|138|31|23|E|type:mountain_scale:100000|format=dms|display=inline,title}}
| coordinates_ref = <ref>{{Cite web |url=https://www.data.jma.go.jp/svd/vois/data/tokyo/306_Asamayama/306_index.html |title=浅間山 |access-date=2022-05-23 |publisher=[[気象庁]] |language=ja}}</ref>
| topo = [[Geographical Survey Institute]] 25000:1 浅間山<br />50000:1 長野
| type = Complex volcano
| age = [[Late Pleistocene]]–[[Holocene]]<ref name="Semless" />
| last_eruption = 7 August 2019
| first_ascent = 
| easiest_route = 
}}

{{nihongo|'''Mount Asama'''|浅間山|Asama-yama}} is an active [[complex volcano]] in central [[Honshū]], the main island of [[Japan]]. The volcano is the most active on Honshū.<ref name="Smithsonian" /> The [[Japan Meteorological Agency]] classifies Mount Asama as rank A.<ref name="qvoj-list"/> It stands {{convert|2568|m|ft}} above [[sea level]] on the border of [[Gunma prefecture|Gunma]] and [[Nagano prefecture]]s.<ref>{{Cite web |title=浅間山とは |url=https://kotobank.jp/word/%E6%B5%85%E9%96%93%E5%B1%B1-25110 |access-date=2022-05-23 |website=[[Kotobank]] |date=16 June 2015 |language=ja}}</ref> It is included in ''[[100 Famous Japanese Mountains]]''.

==Geology==
Mount Asama sits at the conjunction of the [[Izu–Bonin–Mariana Arc]] and the [[Northeastern Japan Arc]].<ref name="Smithsonian">{{cite gvp|vnum=283110|title=Asama|access-date=2 February 2009}}</ref> The mountain is built up from non-alkali mafic and pyroclastic volcanic rocks dating from the [[Late Pleistocene]] to the [[Holocene]].<ref name="Semless">{{cite web|url=http://riodb02.ibase.aist.go.jp/db084/Hokurikuzoom_e.html|title=Hokuriku|year=2007|work=Seamless Digital Geological Map of Japan|publisher=Geological Survey of Japan, AIST|access-date=2 February 2009|url-status=dead|archive-url=https://web.archive.org/web/20090206100915/http://riodb02.ibase.aist.go.jp/db084/Hokurikuzoom_e.html|archive-date=6 February 2009}}</ref> The main rock types are [[andesite]] and [[dacite]].<ref name="QVoJ"/>
[[File:AsamaYamaS.jpg|thumb|200px|left|Viewed from the north]]
Scientists from the [[University of Tokyo]] and [[Nagoya University]] completed their first successful imaging experiment of the interior of the volcano in April 2007. By detecting sub-atomic particles called [[muons]] 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.<ref>{{cite journal | bibcode = 2007E&PSL.263..104T | title=High resolution imaging in the inhomogeneous crust with cosmic-ray muon radiography: The density structure below the volcanic crater floor of Mt. Asama, Japan | journal=Earth and Planetary Science Letters | volume=263 | page=104 | year=2007 |author1=Tanaka, Hiroyuki K. M. |author2=Nakano, Toshiyuki |author3=Takahashi, Satoru |author4=Yoshida, Jyunya |author5=Takeo, Minoru |author6=Oikawa, Jun |author7=Ohminato, Takao |author8=Aoki, Yosuke |author9=Koyama, Etsuro |author10=Tsuji, Hiroshi |author11=Niwa, Kimio | issue=1–2 | doi=10.1016/j.epsl.2007.09.001}}</ref>

A University of Tokyo [[vulcanology|volcano observatory]] 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]].<ref>{{cite web|url=http://meetingorganizer.copernicus.org/EGU2009/EGU2009-5839.pdf|title=Real-Time Multi-GAS sensing of volcanic gas composition: experiences from the permanent Etna and Stromboli networks, Geophysical Research Abstracts, Vol. 11, EGU2009-5839}}</ref>

There is also another mountain called Asama (朝熊山, ''Asama-yama'') of only 555 meters in [[Mie Prefecture]].<ref>{{cite web |last1=Bastion |first1=Arlene |title=Huffing and Puffing Up Mt Asama |url=https://en.japantravel.com/mie/huffing-and-puffing-up-mt-asama/58547 |website=Japan Travel |date=11 April 2019 |access-date=13 April 2022}}</ref>

==Eruptive history==
[[File:Mount Asama Relief Map (a), SRTM-1.jpg|thumb|170px|Relief map]]
The geologic features of this active volcano are closely monitored with [[seismograph]]s and strategically positioned video cameras.<ref name="seach1">[http://www.volcanolive.com/index.html  VolcanoLive.com]: [http://www.volcanolive.com/asama.html  Asama]</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.<ref>Yasui, Maya, Takahashi Masaki, and Sakagami Masakuki. [http://sciencelinks.jp/j-east/article/200604/000020060406A0079797.php  "Textural Variety in the Eruptive Products of Vulcanian Eruptions between 1108 A.D. and 2004 A.D. on Asama-Maekake Volcano,"] ''Bulletin of the Volcanological Society of Japan'' (''Kazan''). Vol. 50, No. 6 (2005). pp. 501–517.</ref>

===''Tennin'' eruption (1108)===
The eruption of Mount Asama in 1108 (''[[Tennin (era)|Tennin]] 1'') has been the subject of studies by modern science.<ref>[http://www.cnrs.fr/en/aboutCNRS/overview.htm  Centre national de la recherche scientifique (CNRS)] {{webarchive|url=https://web.archive.org/web/20090225122406/http://www.cnrs.fr/en/aboutCNRS/overview.htm |date=25 February 2009 }}, France: Yoshida, Minoru and Aoyagi, Ryugi. [http://cat.inist.fr/?aModele=afficheN&cpsidt=16211153  "Fluorine and chlorine contents in the products of the 1108 (''Tennin'') eruption of Asama volcano,"] ''Bulletin of the Volcanological Society of Japan'' (''[[Kazan]]'').  Vol. 49, No. 4 (2004). pp. 189–199.</ref>  Records suggest that the magnitude of this plinian eruption was twice as large as that of the [[Tenmei eruption|''Tenmei'' catastrophe in 1783]].<ref>Hayakawa, Yukio and Hideko Nakajima. [http://www.edu.gunma-u.ac.jp/~hayakawa/volcanoes/asama/asamasiryo/abstract.html  "Volcanic Eruptions and Hazards of Asama Written in Historical Records" (abstract)], ''Bulletin of the Volcanological Society of Japan'' (''[[Kazan]]''). 19 July 2006.</ref>

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]] which had increased sulfate deposition in 1108 CE. In the late [[Heian Period]] (794–1185) the diary of the court noble [[Fujiwara no Munetada]] 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.<ref name="Swiss-study">{{cite web|url=http://www.asahi.com/ajw/articles/13421025 |title=Mt. Asamayama eruption in 1108 may have led to famine in Europe |year=2020 |author= Yu Fujinami |work=The Asahi Shimbun |publisher=Asahi |access-date=20 June 2020 |url-status=live |archive-url=https://web.archive.org/web/20200621035330/http://www.asahi.com/ajw/articles/13421025 |archive-date=21 June 2020 }}</ref>

===''Tenmei'' eruption (1783)===
{{See|Tenmei eruption}}

Mount Asama erupted in 1783 (''[[Tenmei]] 3''), causing widespread damage.<ref>Titsingh, Isaac. (1834). [https://books.google.com/books?id=18oNAAAAIAAJ&dq=nipon+o+dai+itsi+ran&pg=PP9  ''Annales des empereurs du japon,'' p. 420.]</ref>  The three-month-long [[plinian]] eruption that began on 9 May 1783, produced [[andesitic]] pumice falls, [[Pyroclastic flow|pyroclastic]] flows, lava flows, and enlarged the cone. The climactic eruption began on 4 August and lasted for 15 hours,<ref name="Richards2003">{{cite book|last=Richards|first=John F.|title=The Unending Frontier: An Environmental History of the Early Modern World|url=https://books.google.com/books?id=i85noYD9C0EC&pg=PA177|access-date=2 August 2013|year=2003|publisher=University of California Press|isbn=9780520939356|page=177}}</ref> and contained pumice falls and pyroclastic flows.<ref name="seach1"/>  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]] which generated further injections of pumice into the air.<ref>Yasui, Maya and Takehiro Koyaguchi. [https://doi.org/10.1007%2Fs00445-003-0308-8  "Sequence and eruptive style of the 1783 eruption of Asama Volcano, central Japan: a case study of an andesitic explosive eruption generating fountain-fed lava flow, pumice fall, scoria flow and forming a cone,"] ''Journal Bulletin of Volcanology'' (''Kasan''). Vol. 66, No. 3 (March 2004). pp. 243–262.</ref>

===1982 eruption===
Explosive eruptions occurred at the summit of Asama volcano on 26 April. Fine ash fell in Tokyo, {{convert|130|km|abbr=on|-1}} to the SE, for the first time in 23 years.<ref name="seach1"/>

===1983 eruptions===
An explosive eruption occurred on 8 April. Incandescent tephra was ejected, and ash fell {{convert|250|km|abbr=on}} from the volcano.<ref name="seach1"/>

===1995 earthquakes===
In April 1995, more than 1000 earthquakes were detected at the volcanic mountain.<ref name="seach1"/>

===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.<ref name="seach1"/> The eruption sent ash and rock as far away as {{convert|200|km|abbr=on}}.<ref name="BBC1" />

===2008 eruptions===
Three small ash eruptions occurred at Asama volcano in August 2008. This was the first activity at the volcano since 2004.<ref name="seach1"/>

===2009 eruptions===
Mount Asama erupted in early February 2009, sending ash to a height of {{convert|2|km|ft|abbr=on}},<ref name="BBC1">[http://news.bbc.co.uk/2/hi/asia-pacific/7864266.stm "Volcano erupts close to Tokyo,"] BBC. 2 February 2009.</ref> and throwing rocks up to {{cvt|1|km}} from the crater. Ash fall was reported in Tokyo, {{convert|145|km|abbr=on}} southeast of the volcano crater. On 16 February there were 13 recorded volcanic earthquakes and an eruption emitting smoke and ash in a cloud {{convert|400|m|abbr=on}} high.

Mount Asama continued to have small eruptions, tremors and earthquakes in February and remained on level-3 alert, with a danger zone within {{cvt|4|km}} of the crater.<ref name="Japanese Meteorological Agency">[http://www.seisvol.kishou.go.jp/tokyo/STOCK/volinfo/VK20090217160010_306.html] {{Webarchive|url=https://web.archive.org/web/20090221082738/http://www.seisvol.kishou.go.jp/tokyo/STOCK/volinfo/VK20090217160010_306.html|date=21 February 2009}} 18 February 2009.</ref>

===2019 eruption===
A small eruption occurred on August 7th, 2019, with smoke reaching about 1,800 meters above the mountain.<ref>{{Cite web |last=NEWS |first=KYODO |title=Minor volcanic eruption observed on Mt. Asama, alert level raised |url=https://english.kyodonews.net/news/2019/08/357bd49cca82-volcanic-activity-alert.html |access-date=2024-10-15 |website=Kyodo News+}}</ref>

===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.<ref name="seach1"/>

Note: The dates of eruptions featured in this article appear in bold italics.

== Onioshidashi ==
{{multiple image |align=right |direction=horizontal |total_width=350
 |image1= Onioshidashi Lava flow.jpg
 |caption1=Map of Onioshidashi lava flow
 |image2= Mt.Asama 05.jpg
 |caption2= Onioshidashi lava flow on the southern foot (erupted in 1783)
}}
'''Onioshidashi''' ({{Langx|ja|鬼押出し}}) "expelling demons" is the name of a [[lava flow]] on the northern slope of Mount Asama.<ref>{{Cite web |title=鬼押出とは |url=https://kotobank.jp/word/%E9%AC%BC%E6%8A%BC%E5%87%BA-453673 |access-date=2022-05-22 |website=Kotobank |language=ja}}</ref> The lava flow that erupted in 1783 [[Tenmei eruption]] was solidified.<ref>{{Cite web |title=鬼押出しとは |url=https://kotobank.jp/word/%E9%AC%BC%E6%8A%BC%E5%87%BA%E3%81%97-823039 |access-date=2022-05-22 |website=Kotobank |language=ja}}</ref> Now, it is known as a tourist destination.<ref>{{Cite web |title=鬼押出岩とは |url=https://kotobank.jp/word/%E9%AC%BC%E6%8A%BC%E5%87%BA%E5%B2%A9-40837 |access-date=2022-05-22 |website=Kotobank|language=ja}}</ref>

== Asama Volcano Museum ==
[[File:ASAMA_Volcano_Museum_2017-04.jpg|left|thumb|200x200px|Asama Volcano Museum]]
The Asama Volcano Museum ({{Nihongo2|浅間火山博物館}}), {{Convert|4|km|mi|abbr=on}} from the crater of the Mount Asama,<ref name="yomiuri">[https://www.yomiuri.co.jp/local/gunma/news/20200807-OYTNT50150/ 浅間火山博物館閉館へ], 『読売新聞』(''[[Yomiuri Shimbun]]''), 8 August 2020. Accessed 1 July 2021.</ref> open from 1993 to 2020, explained volcanoes.

The museum was in [[Naganohara, Gunma|Naganohara-machi]], [[Agatsuma District, Gunma|Agatsuma-gun]], [[Gunma Prefecture]]. 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:<ref name="jomo">[https://www.jomo-news.co.jp/news/gunma/society/232071 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 Shimbun|Jōmō Shinbun]]''), 9 August 2020. Accessed 1 July 2021.</ref> this gradually fell to 23,000.<ref name="yomiuri" /> In the later years of the museum, most of the visitors were on school excursions.<ref name="jomo" /> 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.<ref name="yomiuri" /><ref name="jomo" />

A nearby building, Asama memorial hall<!-- Name in English, if any, unknown --> ({{Nihongo2|浅間記念館}}) exhibited motorbikes; the plan in summer 2020 was to move these to a municipally owned tourist facility, Asama pasture<!-- Name in English, if any, unknown --> ({{Nihongo2|浅間牧場}}), and to move some of the exhibits of the volcano museum to the memorial hall.<ref name="yomiuri" />

== Gallery ==
<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]]

</gallery>

==In popular culture==
Mount Asama served as the backdrop to Japan's first colour film, ''[[Carmen Comes Home]]''.<ref>{{Cite web|url=http://filmref.com/notes/archives/2006/08/carmen_comes_home_1951.html|title=Notes on the Cinema Stylographer: Carmen Comes Home, 1951|website=filmref.com|access-date=15 January 2017|archive-url=https://web.archive.org/web/20161012163308/http://www.filmref.com/notes/archives/2006/08/carmen_comes_home_1951.html|archive-date=12 October 2016|url-status=dead}}</ref> 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]]'', the Eighth Angel, Sandalphon, was located inside Mount Asama.<ref name="FujieBooks2004">{{cite book|first1=Kazuhisa 
|last1=Fujie |first2=Martin |last2=Foster|title=Neon Genesis Evangelion: The Unofficial Guide|url=https://books.google.com/books?id=2SX3lUu_IPAC&pg=PA176|year=2004|publisher=DH Publishing Inc|isbn=978-0-9745961-4-3|page=176}}</ref>

==See also==
*[[Tenmei eruption]]

==Notes==
{{Reflist|refs=
<ref name="QVoJ">{{cite web|url=http://riodb02.ibase.aist.go.jp/strata/VOL_JP/EN/vol/91.htm|archive-url=https://archive.today/20121219004930/http://riodb02.ibase.aist.go.jp/strata/VOL_JP/EN/vol/91.htm|url-status=dead|archive-date=19 December 2012|title=ASAMA-YAMA|year=2006|work=Quaternary Volcanoes in Japan|publisher=Geological Survey of Japan, AIST|access-date=3 February 2009}}</ref>
<ref name="qvoj-list">{{cite web|url=http://riodb02.ibase.aist.go.jp/strata/VOL_JP/EN/active_v.htm|archive-url=https://archive.today/20121209072706/http://riodb02.ibase.aist.go.jp/strata/VOL_JP/EN/active_v.htm|url-status=dead|archive-date=9 December 2012|title=List of Active Volcanoes in Japan|year=2006|work=Quaternary Volcanoes in Japan|publisher=Geological Survey of Japan, AIST|access-date=3 February 2009}}</ref>
}}

==References==
*[[John Whitney Hall|Hall, John Whitney]] (1955). '' [[Tanuma Okitsugu]], 1719–1788: Forerunner of Modern Japan, '' Cambridge: [[Harvard University Press]].
*Hayakawa, Yukio and Hideko Nakajima. [http://www.edu.gunma-u.ac.jp/~hayakawa/volcanoes/asama/asamasiryo/abstract.html  "Volcanic Eruptions and Hazards of Asama Written in Historical Records" (abstract)], ''Bulletin of the Volcanological Society of Japan'' (''[[Kazan]]''). 19 July 2006.
*[[Timon Screech|Screech]], Timon (2006). [https://books.google.com/books?id=BLzQA7cpr7wC  ''Secret Memoirs of the Shoguns: Isaac Titsingh and Japan, 1779–1822.''] London: [[RoutledgeCurzon]]. {{ISBN|978-0-7007-1720-0}} (cloth); {{ISBN|978-0-203-09985-8}} (electronic)
*[[Isaac Titsingh|Titsingh, Isaac]] (1834). [Siyun-sai Rin-siyo/[[Hayashi Gahō]], 1652], ''[[Nipon o daï itsi ran]]; ou, [https://books.google.com/books?id=18oNAAAAIAAJ&q=nipon+o+dai+itsi+ran  Annales des empereurs du Japon.]''  Paris: [[Royal Asiatic Society|Oriental Translation Fund of Great Britain and Ireland]].

==External links==
{{Commons category|Mount Asama}}
* [http://www.data.jma.go.jp/svd/vois/data/tokyo/306_Asamayama/306_index.html Asamayama] – Japan Meteorological Agency {{in lang|ja}}
* {{cite web|url= http://www.data.jma.go.jp/svd/vois/data/tokyo/STOCK/souran_eng/volcanoes/045_asamayama.pdf |title=Asamayama: National catalogue of the active volcanoes in Japan }} – Japan Meteorological Agency
* [https://gbank.gsj.jp/volcano/Act_Vol/asama/index-e.html Asama Volcano] – Geological Survey of Japan
* [http://volcano.si.edu/volcano.cfm?vn=283110 Asamayama] – Smithsonian Institution: Global Volcanism Program

{{100 Famous Japanese Mountains}}

{{Authority control}}

{{DEFAULTSORT:Asama}}
[[Category:Mountains of Gunma Prefecture]]
[[Category:Mountains of Nagano Prefecture]]
[[Category:Volcanoes of Honshū]]
[[Category:Subduction volcanoes]]
[[Category:Active volcanoes]]
[[Category:VEI-5 volcanoes]]
[[Category:Complex volcanoes]]
[[Category:18th-century volcanic events]]
[[Category:Volcanoes of Gunma Prefecture]]
[[Category:Volcanoes of Nagano Prefecture]]
[[Category:Highest points of Japanese national parks]]
[[Category:Calderas of Honshū]]