伊豆大島 1986 年割れ目噴火の拡大速度

概要

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Izu-Oshima Volcano, Japan, erupted early on the evening of November 21, 1986, to form fire fountains along two major fissures running linearly southeast to northwest, one on the caldera floor (eruption B) and the other on the flank outside the northern caldera rim (eruption C). During the eruption B, the individual vents opened in succession towards the southeast and the northwest with a velocity of 0.42 m/s. During the eruption C, the individual vents also opened in succession towards the northwest with a velocity of 0.23 m/s. An additional feature of interest is a temporal and spatial gap between the erupion C. If this gap was caused by subsurface magma movement, its velocity is estimated to be 0.29 m/s. This velocity is so close to the extension velocity of the eruptions B and C that bilateral magma flow over the length of 3.3 km is inferred, though the possibility of accidental coincidence cannot be excluded.
特定非営利活動法人日本火山学会の論文
1988-06-30