2:45 PM - 3:00 PM
[SVC12-03] Temporal variation of the ash component of the 2014-15 Aso Nakadake eruption
Keywords:eruption, volcanic ash, magma, Aso
We trace the temporal change of the grain components of the volcanic ash. The volcanic ash erupted from the onset of the eruption in November till December 10 contains dark-colored opaque glassy grain and cryptocrystalline black grains. Since middle of December, pale-brownish glassy grains occupy the major part of the products. These glassy grains are subdivided into i) blocky grain, with fractured surface, lower vesicle contents, ii) sponge-like grain, with higher vesicle contents surrounded by fractured surface, iii) elongated grain, with smooth surface and elongated bubbles. Some elongated grains show Pele′s hair shape. The volcanic ash erupted in December 15-16, 25-27, January 13-16 contains elongated glassy grains.