Akan Volcanic Complex

Akan Volcanic Complex (阿寒岳, Akan-dake)
Volcanic Complex
Mount Meakan, Akan-Fuji and Mount Oakan on a satellite image of Eastern Hokkaido
Country	Japan
State	Hokkaidō
Regions	Kushiro Subprefecture, Tokachi Subprefecture
Districts	Ashoro District, Shiranuka District
Municipalities	Ashoro, Kushiro, Shiranuka
Highest point	Mount Meakan
- elevation	1,499 m (4,918 ft)
- coordinates	43°23′11″N 144°00′32″E / 43.38639°N 144.00889°E / 43.38639; 144.00889
Geology	Volcanic
Orogeny	island arc

Akan Volcanic Complex is a volcanic group of volcanoes that grew out of the Akan caldera.^[1] It is located within Akan National Park, about 50km Northwest of Kushiro in eastern Hokkaidō, Japan.

Description

Mount Meakan and Akan Fuji from Mount Oakan (July 2008).

A number of peaks are arranged around the rim of Lake Akan (aka Akan-ko^[2]), which fills a 24x 13km caldera^[3], the tallest being Me-Akan (Meakan), O-Akan (Oakan) and Akan-Fuji.^[1]

Vapor rising from Mount Meakan, seen from the lakeside of Lake Akan.

Oakan is prominently located at the Northeast side of the caldera, while Meakan occupies the opposite, Southwest side, in a cluster of nine stratovolcanoes that include Akan-Fuji, one of many symmetrical Japanese volcanoes named after the renowned Mount Fuji, and Fuppushi volcano^[4] (aka Fuppushi-dake, not to be confused with Mount Fuppushi, which is located in Southwestern Hokkaido).

Volcanology

The Akan caldera was formed 31,500 years ago. Its elongated shape is due to its incremental formation during major explosive eruptions, from the early to the mid-Pleistocene periods.

The Nakamachineshiri crater of Meakan volcano was formed during a major eruption about 13,500 years ago.

The Me-Akan group of nine overlapping cones on the eastern side of Lake Akan has had mild eruptions since the beginning of the 19th century.^[5] The last eruption of this historical volcano was in 2008.^[3]

Oakan, Meakan, Furebetsu and Fuppushi are the major post-caldera volcanoes of the Akan volcanic complex.^[1]

Me-Akan is one of the most active volcanoes of Hokkaido. Its summit contains the active craters of Ponmachineshiri and Naka-Machineshiri, sites of frequent phreatic eruptions in historical time. Akan-Fuji and O-Akan have not erupted in historical time.^[4]

Akan is rated with a volcanic explosivity index of 4 on the Smithsonian VEI scale, the scale's fourth-highest score, based on the volcano's largest known eruption, around 7050 BC.^[6]

Following are prominent features of Akan:^[3]

Cones

• Mount Meakan (1499 m) Stratovolcano
• Akan Fuji (Akan-Fuji, aka Akan-Huji) (1476 m) Stratovolcano
• Kita-Yama (1400 m) Cone
• O-Akan (Mount Oakan) (1371 m) Stratovolcano
• Kenga-Mine Cone 1336 m
• Nishi-Yama (Nisi-Yama) (1300 m) Cone
• Fuppushi (Huppusi) (1226 m) Stratovolcano
• Miname-Dake (1217 m) Stratovolcano
• Higashi-Dake (Higasi-Dake) (1140 m) Cone
• Furebetsu (Hurebetu) (1098 m) Stratovolcano
• Kobu-Yama Cone
• Futatsu-Dake Pyroclastic cone

Craters

• Nakamachineshiri (Nakamatineshiri) Crater
• Ponmachineshiri (Ponmatinesiri) Crater

Thermal features

• Akan-Kohan Thermal Feature

Other peaks

• Mount Ken^{[citation needed]}
• Mount Ahoro^{[citation needed]}

References

1. ^ ^{a b c} "AKAN Caldera". Quaternary Volcanoes of Japan, Geological Survey of Japan, AIST, 2006. http://riodb02.ibase.aist.go.jp/strata/VOL_JP/EN/vol/218b.htm. Retrieved 2011-03-09. 
2. ^ "Akan-ko: Japan". Geographical Names. http://geographic.org/geographic_names/name.php?uni=-332580&fid=3243&c=japan. Retrieved 2011-03-09. 
3. ^ ^{a b c} "Akan". Global Volcanism Program, Smithsonian National Museum of Natural History. http://www.volcano.si.edu/world/volcano.cfm?vnum=0805-07=. Retrieved 2011-03-09. 
4. ^ ^{a b} "Akan Volcanic Complex, Japan". Volcano Photos. http://www.geographic.org/photos/volcanoes/volcano_photos_91.html. Retrieved 2011-03-09. 
5. ^ "MEAKAN-DAKE". Quaternary Volcanoes of Japan, Geological Survey of Japan, AIST, 2006. http://riodb02.ibase.aist.go.jp/strata/VOL_JP/EN/vol/218f.htm. Retrieved 2011-03-09. 
6. ^ "Large Volcano Explocivity Index". Countries of the World. http://www.allcountries.org/ranks/volcano_explocivity_index_ranks.html. Retrieved 2011-03-09. 

External Links

• OAKAN-DAKE, Quaternary Volcanoes of Japan, Geological Survey of Japan, AIST, 2006