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Myojin Knoll Vulkansubmarine volcano -360 m / -1,181 ft
Izu Islands, Japan, 32.1°N / 139.85°E Aktueller Status: nicht aktiv (1 von 5)
Typische Aktivität: Explosiv
Ausbrüche des Myojin Knoll: unknown Letzte Erdbeben in der Nähe:
The highest point on the western caldera rim is a pumice-mantled remnant of the cone before the caldera formation, and reaches to a depth of 360 m. The eruption that formed the caldera could have been only a few thousand years ago. Beschreibung:The walls of the caldera, also known as Kita-Bayonnaise (North Bayonnaise) reveal rhyolitic lava flows, shallow intrusions, and volcaniclastic deposits. A voluminous blanket of coarse rhyolitic pumice from the caldera-forming eruption mantles the caldera rim and its outer flanks.Post-caldera eruptions formed a lava dome that rises 250 m above the caldera floor. The age of the caldera is not known, but was considered by Fiske et al. (2001) to perhaps be as young as a few thousand years. An active hydrothermal vent field lies on the eastern caldera floor and has produced a polymetallic sulfide deposit from vent chimneys up to 30 m high that emit fluids as hot as 278 degrees C. --- Reference cited: Fiske R S, Naka J, Iizasa K, Yuasa M, Klaus A (2001) "Submarine silicic caldera at the front of the Izu-Bonin arc, Japan: voluminous seafloor eruptions of rhyolite pumice.", Geol Soc Amer Bull, 113, pp 813-824 (from: Smithsonian / GVP volcano information) |
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