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| Izu-Tobu | |
|---|---|
| Izu-Tobu volcano field | |
 Mount Ōmuro, a symbolic pyroclastic cone of the Izu-Tobu volcano field | |
| Highest point | |
| Coordinates | 34°53′59″N 139°05′52″E / 34.89972°N 139.09778°E / 34.89972; 139.09778 |
| Naming | |
| Native name | 伊豆東部火山群 (Japanese) |
| Geography | |
  Izu-TobuIzu Peninsula, Shizuoka Prefecture, JapanShow map of Japan Izu-TobuIzu-Tobu (Shizuoka Prefecture)Show map of Shizuoka Prefecture
| |
| Geology | |
| Mountain type | Pyroclastic cones |
| Last eruption | July 1989 |
Izu-Tobu (伊豆東部火山群, Izu Tōbu Kazangun) is a large, dominantly basaltic range of volcanoes on the east side of the Izu Peninsula which lies on the Pacific coast of the island of Honshu in Japan. The field covers a total area of 400 km. The only recorded activity was a submarine phreatic eruption, between the city of Ito and Hatsushima island, that lasted for just 10 minutes in 1989. Ito, home to 74,000 people, is known for its hot springs.
Morphology
The field covers the east side of the Izu Peninsula. It consists of several small stratovolcanoes (mostly Pleistocene in age) and overlapping pyroclastic cones, which covers 400 km in area. There are 70 young monogenetic volcanoes on land. Kawagodaira maar, which is about 3,000 years old, produced a large Holocene eruption that sent pyroclastic flows over a wide area.
Eruptions
1989 eruption
The only recorded eruption was an event on 13 July 1989. Two earthquakes, on 30 June and 9 July took, place on the Izu-Tobu Volcano. On 13 July, a seismometer recorded seismicity, a research vessel, the RV Takuyo reported hearing an explosion sound from the sea floor followed by a 30-second vibration at 18:33 pm. At 18:40 pm the crew reported that the sea domed up 500 m from the vessel, then a grey-black plume rose from the area, five more domes were reported in the next 5 minutes which caused the ship to vibrate. After that seismicity declined.
This marks the only known eruptive activity at Izu-Tobu. The next day a survey using an unmanned vessel discovered a new cone 100 metres underwater. The cone was around 450 Metres wide with a summit crater 200 m in diameter. The height of the cone above the sea floor was only 10 m in height.
The University of Tokyo monitors Izu-Tobu 24 hours a day.
Distinct cones
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See also
References
- "Izu-Tobu". Global Volcanism Program. Smithsonian Institution. Retrieved 2021-06-24.
- Volcanolive.com
- ^ "Shizuoka University – Masato Koyama's website". Archived from the original on 2020-05-11. Retrieved 2012-04-27.
- ^ Izu Shimbun newspaper article "伊豆の大地の物語"
- 環境省自然環境局生物多様性センター 1980年の第2回自然環境保全基礎調査 陸水域関係調査報告書 （湖沼） 全国版 PDF
External links
- Izu-Tobu Volcanoes – Japan Meteorological Agency (in Japanese)
- "Izu-Tobu Volcanoes : National catalogue of the active volcanoes in Japan" (PDF). – Japan Meteorological Agency
- Izu Tobu Volcano Group – Geological Survey of Japan
- Eruptive history of the Higashi Izu monogenetic volcano field – Shizuoka University