Landforms of submarine volcanoes in central part of the Izu-Ogasawara Arc, by multi-beam sounding system.
There are many submarine volcanoes along the Izu-Ogasawara Arc. The central part of the arc has some large volcanoes as caldera volcanoes, the diameters of which exceed 5 km, and conical volcanoes more than 3000 m high from the ocean floor. The authors surveyed some volcanoes as follows Higasi Aogasima, Kita-Beyonesu, Sitiyo seamounts (including seven seamounts Nitiyo Smt, Getuyo Smt, Kayo Smt, Suiyo Smt, Mokuyo Smt, Kinyo Smt, and Doyo Smt), and Nisino Sima by the multi-beam sounding system of survey vessel ”Takuyo”of M.S.A.J., and drew bathymetric charts (geomorphological maps) of them. The surveyed submarine volcanoes are geomorphologically classified into five types : large-scale caldera volcanoes (Higasi-Aogasima, Kita- Beyonesu), simple or complexed conical stratovolcanoes with pinnacle top (Getuyo Smt, Kayo Smt, and Nisino-Sima), conical stratovolcanoes with small calderas or craters on its top (Suiyo Smt, Mokuyo Smt, and Kin yo Smt), a conical stratovolcano with large horseshoe shaped calderas on its slope (Doyo Smt) , and a volcano much deformed by normal faults (Nitiyo Smt). The Higasi-Aogasima and Kita-Beyeonesu calderas were formed in one or two eruption cycles with ejection of a large mount of pumice fragments which were dredged by ”Takuyo”and other survey vessels. The small scale caldera and crater on the top of Mokuyo Smt indicate that some explosive events occurred. The large horseshoe-shaped caldera of the Doyo Smt is caused by collapsing of the northeastern part of the mountain. The debris from the horseshoe-shaped caldera flowed into the Ogasawara Trough and formed a large crescent-shaped hill, 60 x 30 km wide and less than 70 m high.
| Autores principales: | , , |
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| Formato: | Journal Contribution biblioteca |
| Idioma: | Japanese |
| Publicado: |
1991
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| Acceso en línea: | http://hdl.handle.net/1834/16079 |
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