熊本大学学術リポジトリ Kumamoto University Repositor Title 阿蘇火山中岳における 2005 年の火山活動と噴出物 Author(s) 宮縁, 育夫 ; 池辺, 伸一郎 ; 渡辺, 一徳 Citation 火山, 52(3): Issue date

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(1)熊本大学学術リポジトリ Kumamoto University Repository System Title. 阿蘇火山中岳における2005年の火山活動と噴出物. Author(s). 宮縁, 育夫; 池辺, 伸一郎; 渡辺, 一徳. Citation. 火山, 52(3): 133-147. Issue date. 2007-06-29. Type. Journal Article. URL. http://hdl.handle.net/2298/37043. Right. © 2007 特定非営利活動法人日本火山学会.

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(4) ,**0 , +0 ,**1 . . . The ,**/ Activity and Products of Nakadake Crater, Aso Volcano, Japan Yasuo MIYABUCHI῍, Shin-ichiro IKEBE῍῍ and Kazunori WATANABE῍῍῍ Small ash emissions were frequently observed from a crater lake, in which the amount of water decreased considerably, at Nakadake, Aso Volcano, southwestern Japan, between April and August ,**/. During this period, major ash emitting events, which produced mostly white aggregated ash, occurred on April +., June +*ῌ +,, June ,+ (.., tons) and July ,/ (+., tons). Ash emissions at the Nakadake crater in ,**/ were classified as three types : gentle release of white aggregated ash from fumaroles inside the crater lake (e.g. daytime of April +., June +*ῌ+, and July ,/); short (ca. ,* seconds) gas-and-ash emission through the crater lake (April +. ,* : .+); and emission of black ash from an almost dry vent (June ,+). All products from these ash emissions were composed of fine-grained (+ mm) glass shards, crystals and lithic fragments, and contained neither lapilli nor blocks. Although the glass shards show varying degrees of crystallization and alteration, clear glass shards, which appear fresh and are not altered, may be juvenile materials. Key words : ash emission, clear glass shards, crater lake, Nakadake, Aso Volcano. +ῌ ῐ ῎ ῑ ῏. + . }~;+eQ[0C3 !"#$. < (,**/) "#$%-./;. %& '()*+,-./012+3 ,**- 1 '. +@a]58 9YZ ,**- 1 ' ,**. +. ,**. + 45"#$%6758 9-

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(266) 5 5 5@5 (,**-) #$ QRL¡ ¢ pR£5tu¤ +, 0,ῌ0/. Ono, K., Watanabe, K., Hoshizumi, H. and Ikebe, S. (+33/) Ash eruption of the Naka-dake crater, Aso volcano, southwestern Japan. J. Volcanol. Geotherm. Res., 00, +-1ῌ+.2. ¥¦§5>?@A512345¨3©5B?C@ (+33/) #$DEFXTUX ª .* +--ῌ+/+. 7 5 5«¬® (,**/) #$DE xy()ghij 0\RZ ,**/ &¯° pZ±²³´ /3. Walker, G.P.L. (+31-) Explosive volcanic eruptionsµa new classification scheme. Geologische Rundschau, 0,, .-+ῌ..0. Walker, G.P.L. (+32*) The Taupo pumice : products of the most powerful known (ultra-plinian) eruption? J. Volcanol. Geotherm. Res., 2, 03ῌ3.. Wright, J.V., Smith, A.L. and Self, S. (+32*) A working terminology of pyroclastic deposits. J. Volcanol. Geotherm. Res., 2, -+/ῌ--0. %`´¶· ¸¹'.

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