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 km2. 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 km2 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 ImageNameLocationTypeHeightEruptionCoordinatesCommentsMount Ōmuro(大室山)ItōCinder coneLava flow formed the Jōgasaki coast.(Right)Mount Komuro(小室山)ItōCinder coneMount Io(伊雄山)ItōCinder coneMount Tōgasa(遠笠山)Izu andHigashizuCinder coneOldest volcano in Izu-Tobu volcano fieldKawagodaira(皮子平)IzuVolcanic craterMount Maruno(丸野山)IzuCinder coneMount Sukumo(巣雲山)IzuCinder coneMount Hachikubo(鉢窪山)IzuCinder coneLava flow from Mount Hachikubo formed Jōren Falls.Mount Maru(丸山)IzuCinder coneMount Takatsuka(高塚山)IzunokuniCinder coneCinder cone was halved by quarrying.Mount Hachino(鉢ノ山)KawazuCinder cone(Left)Mount Yahazu(矢筈山)ItōLava dome(Right)Mount Anano(孔ノ山)ItōLava domeMount Iwano(岩ノ山)IzuLava domeIppeki lake(一碧湖)ItōMaarSurface elevation 185 m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 PDFJōgasaki coast (城ヶ崎海岸)ItōLava flow-This coast was mostly formed by lava flow from Mount Ōmuro. Teishi knoll(手石海丘)Sagami Sea (off Itō)Volcanic craterYoungest volcano in Izu-Tobu volcano field. Eruption video by Japan Coast Guard
See also List of volcanoes in Japan List of mountains in Japan
References
Volcanolive.com
External links
Izu-Tobu Volcanoes – Japan Meteorological Agency – Japan Meteorological Agency Izu Tobu Volcano Group – Geological Survey of Japan Eruptive history of the Higashi Izu monogenetic volcano field – Shizuoka University