Tectonics and Volcanoes of Japan


Japan's volcanoes are part of five volcanic arcs. The arcs meet at a triple junction on the island of Honshu. The Northeast Honshu Arc and the Kurile Arc trend to the northeast. The Izu-Bonin Arc trends to the southeast. The Southwest Honshu Arc and the Ryukyu Arc trend to the south west. The Northeast Honshu Arc and the < a href="http://volcano.und.edu/vwdocs/volc_images/north_asia/kuriles.html">Kurile Arc formed by the subduction of the Pacific Plate under the Eurasian Plate. The Izu-Bonin Arc is the result of subduction of the Pacific Plate under the Philippine Plate. The Southwest Honshu Arc and the Ryukyu Arc formed by the subduction of the Philippine Plate under the Eurasian Plate. Black "teeth" mark the subduction zone with the "teeth" on the overriding plate. The volcanoes shown above make up the northwest quadrant of the "Ring of Fire." Based on Aramaki and Ui (1982).


Cross-section of the Northeast Honshu Arc at 38-40 degrees north. Hot rocks in the asthenosphere are modified by fluids that leave the subducted Pacific Plate. The fluids lower the melting temperature of the rocks in the overlying asthenosphere. The rocks melt to make the magma that feeds volcanoes. From Hasegawa and others (1978).


Distribution of volcanoes and volcanic arcs in Japan. Numbered volcanoes of the Southwest Honshu Arc are: 1. Abu, 2. Sanbe, 3. Oki-dogo, 4. Daisen, and 5. Kannabe. Abu, Oki-dogo, and Kannabe are Holocene shield volcanoes. Sanbe is a caldera that last erupted in 1650 BC. Daisen is a Holocene stratovolcano. The names and status of the other volcanoes are given below. Map based on Simkin and Siebert (1994).

Japan has a long record of documented historic eruptions starting with the eruption of Aso in 553 AD. Aso has proven to be the country's most active volcano with more than 165 eruptions. Japan's largest historic eruption was at Towada in 915 AD. Tephrochronology is commonly used in Japan and allows for a more detailed and balanced view of volcanic activity over the last 10,000 years. Japan leads the world's volcanic regions with 1,274 dated eruptions and 94 volcanoes with dated eruptions. Japan also leads the world with 41 large (VEI greater than or equal to 4) explosive eruptions in the last 10,000 years. The eruption of Kikai 6,300 years ago was one of the largest (VEI=7) eruptions on Earth in the Holocene. Pyroclastic flows, one of the deadliest volcanic hazards, have occurred at 28% of Japan's eruptions.

Japan has several volcano observatories and two Decade Volcanoes, Unzen and Sakura-jima.


Volcanoes of Hokkaido. Names of volcanoes that have erupted since 1900 are given. The other volcanoes are:

1. Oshima-oshima        61. Nipesotsu-Upepesanke
11. E-san       	62. Shikaribetsu Group
31. Iwaonupuri  	8. Kutcharo
32. Yotei       	81. Mashu
33. Shiribetsu  	82. Rausu
34. Kuttara     	41. Rishiri
6. Daisetsu
Map based on Simkin and Siebert (1994).


Space Shuttle photo STS61A-0468-0002 of southern Kyushu. This photo shows two of Japan's most active volcanoes, Sakura-jima and Aso, and one of the nation's best known volcanoes, Unzen.


Volcanoes of Kyushu. Map based on Simkin and Siebert (1994).


Volcanoes of Kyushu. Map based on Simkin and Siebert (1994).


Volcanoes of the northern part of the Izu-Bonin volcanic arc. Volcano symbols same as above. Map based on Simkin and Siebert (1994).


Volcanoes of the southern part of the Izu-Bonin volcanic arc. Volcano symbols same as above. Map based on Simkin and Siebert (1994).


Sources of Information:

Aramaki, S., and Ui, Y., 1982, Japan, in Thorpe, R.S., ed., Andesites: John Wiley & Sons, p. 259-292.

Hasegawa, A., Umino, N., and Takagi, A., 1978, Double-planed structure of the deep seismic zone in the north-eastern Japan arc: Tectonophysics, v. 47. P. 43-58.

Kuno, H., 1962, Part XI, Japan, Taiwan and Marianas: Catalogue of the active volcanoes of the world including solfatara fields, International Association of Volcanology, Rome, Italy, 332 p.

Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, Arizona, 349 p.



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