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 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 Type URL Right Journal Article 特定非営利活動法人日本火山学会

2 /, (,**1) ,**/,**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 +* +,, 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 +* +, 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 + +,**- 1,**. +,**/,**/. +.,**/ 3,**/. +.,**/ 0 20* *20, Kyushu Research Center, Forestry and Forest Products Research Institute, Kurokami , Kumamoto 20* *20,, Japan. 203,,-, +3-* + Aso Volcano Museum, +3-* + Akamizu, Aso, Kuma- (,**/),**- 1,**. +,**/, mm moto 203,,-,, Japan. 20* 2///,.* + Faculty of Education, Kumamoto University, Kurokami,.* +, Kumamoto 20* 2///, Japan. Corresponding author: Yasuo Miyabuchi yasuo@a#rc.go.jp

3 134,**- /,- +* ;,**.,,** / 3 +,*** ++,** *,**/ (,**/a,,**0),**.,**/ (Fig. +),** /.+,**/ ; 0* 2*. 3-2 / m,** *,**. +* 2,**/ + (Fig.,) / m,,**/. +.,*.+ / (Fig. +) / 1 ;.30 mm 1 (Fig.,),**/ +* 0 2 (Fig. +) -,**/ - + +,**/. 2 (Table +),,**/. +.,* mm s,**/b 0 m,**/ 0 3 Fig. +,**/ g m, 0 +, 0,, 1,0 - g m, 3,**/ (+) (,) (-) - -, (+),**/

4 ,**/ 135 Fig. +. Records of earthquakes, tremor, temperature at the southern crater wall, rainfall, surface temperature and size of Nakadake crater lake and weight of ash deposited at the crater rim. Data except for ash weight are from the Japan Meteorological Agency (JMA). Incandescent phenomena of crater bottom and southern crater wall were observed by JMA and Aso Volcano Museum personnel * +, 1,/ +.,, -, +,**/. +.,**/. +. +,**/c + 1** m 1** m + +/, 10

5 136 Fig.,. Size variations of lake of the +st crater, Nakadake Volcano, in,**/. Photographs taken from the southwestern crater rim. Arrow in each photo shows the northwestern edge of the crater lake. The crater bottom is about,** m across.

6 ,**/ 137 Table +. Major ash emission events at Nakadake +st crater, Aso Volcano in,**/. / m Fig., ;. +.,**/c 0 3 +, +/ +1 +/,**/ / *.2 km (Fig. -A) + mm. +. (Fig..) -./ km, km *.2 km B D D C A + + 1** m + A +., +.1 g m, C +.* g m, +/ km, (Fig..) +.* +.1 g m, +.,/ -,,,**/ 0 +* +,,**/ / mm 0 +, A 0., g m, (Fig. +) * ,**/d 0., g m, 0 +* ++ -, -,**/ 1,/,**/ 1,0 + (Fig. -B) + mm

138 Fig. -. Photographs of the,**/ ash-fall deposits from the Nakadake crater. (A) +. April daytime white aggregated ash adhered to a wood fence at the SW crater rim. Scale in centimeters.

7 138 Fig. -. Photographs of the,**/ ash-fall deposits from the Nakadake crater. (A) +. April daytime white aggregated ash adhered to a wood fence at the SW crater rim. Scale in centimeters. (B),/ July,**/ white ash deposited on a solar panel at site A. Scale in centimeters. (C) +. April,* :.+ muddy ash deposited near site MB. Scale in centimeters. (D),+ June,**/ black ash adhered to a plastic pole at site D (NW crater rim). Top cylinder is about +/ cm across. A -.1 g m, C... g m, (Fig. +) D *./ g m, F *.2 g m, - km..0 km (Fig. /) 1,0 1,* 1,*,0 1,/,-.,. /,**/ + km; +,+., m,-,.,.3../ m s 1,/ 2 1,0 1,/ (Fig. /) Fig. 0., g m, Fig. 0, g m, + g m, + *.*+ km, *.+ g m, +.,

8 no»¼ d!,**/ q 139 Fig... Distribution of the +. April,**/ ash-fall deposits from the Nakadake crater. Base map is + :,/,***-scale topographic map of the Asosan district published by the Geographical Survey Institute. The crater camera of the Aso Volcano Museum (AVM) was installed at the site A. AWS : Asosan Weather Station (JMA). Longitude and latitude are shown as Tokyo Datum. -ῌ- (,),**/. +.,**- 1 +*,**. + +.,**/!" # $%&' ()*' +, -. /!01!" *78. +.,* 9.+ : ;< 9=,* >?@ AB CD!E HIJ KL M N bxyz{ G}Q,* 9.. : +* >u& R~ J b OP < U" -J M FG -J.** m & OP b78 7U" Q. +/ +* 9 J Uno I 04HI $%&' d* Y i) 7?@ X. +. ST U HIV W +0,* 9.+ : AB Y ~ SJ 8 b 7U HIV W +1 X " Q Q. +3 Y Q R!# ST U HIV W Y *.3 km ] Z +0 X " YZ[\ ] ^,* 9.+ : -/ > _ > `ab q «/! SQU" no c J 8d' e fg9= h = QU ªb! ij/!" &U 213 -klz[\ Ym - I V km no pqr st,* 9.+ :./ >u 4² ³ QUµ + mm QUe *' 21±. +. Y *' N OP/! v HwJ U" N ¹ºQU% 7U# d*

140 ±²³ µ ¹ º Fig. /. Distribution of the,/ July,**/ ash from Nakadake crater. Base map is + : /*,***-scale topographic map of the Asosan district published by the Geographical Survey Institute.

9 140 ±²³ µ ¹ º Fig. /. Distribution of the,/ July,**/ ash from Nakadake crater. Base map is + : /*,***-scale topographic map of the Asosan district published by the Geographical Survey Institute. Broken lines indicate isopleths (g/m,). AVM : Aso Volcano Museum. Longitude and latitude are shown as Tokyo Datum. 2 ( 2 2./ +,-9 + BC> :;2 * D2 +,- EF9G AHI JKL M9N >O PQ5 mmr+* mms BTU2 VW (Fig. -C) XY Z[ \]^_B `N ( a b EFFc9M9N Q9@A de fib ghi jk Hk2 $l] 9Z[B`N ( +,- mno*p B + qrsgk tghk2 * $`N 9 u', m rvw*x oyz{ $ 2 * B +, -9 }s GAHI #)W$ ~ m P2* Fig. 0. Relation between area (km,) and weight (g/m,) of the,+ June and,/ July,**/ ash-fall deposits from Nakadake crater. S?2 w *( +q +./ km EF9GAHI ( )# B$ B >r o+,-9 mm B`N (. +3 { B ,*.+! "#$ %&' ( +q *.3 km H fib g,.- km, H ab! o* 9ª N +q (Fig..)( )*+,-./ 012 +,!. +/ +q«9 B }s $ :;2 <=> LB`*( +,- +q + km H ab

,**/ 141 Fig. 1. Distribution of the,+ June,**/ ash from the Nakadake crater. Base map is a + : /*,***- scale topographic map of the Asosan district published by the Geographical Survey Institute.

1) A..3 g m, C -., g m, D.., g m, (Fig. +) + km *., +.. g m, 0 +1 + mm 0,, Fig. 2. Photograph of a vent formed near the northwestern margin of crater lake probably on June,+,,**/.

10 ,**/ 141 Fig. 1. Distribution of the,+ June,**/ ash from the Nakadake crater. Base map is a + : /*,***- scale topographic map of the Asosan district published by the Geographical Survey Institute. Broken lines indicate isopleths (g/m, ). Longitude and latitude are shown as Tokyo Datum., km *.3 km Fig.. ; MB +*.- g m, + km, +* +*.- g m,,*.+ -. (-),**/ 0,+ Ono et al., +33/ ; +33/,**/ 0,, (Fig. 1) A..3 g m, C -., g m, D.., g m, (Fig. +) + km *., +.. g m, mm 0,, Fig. 2. Photograph of a vent formed near the northwestern margin of crater lake probably on June,+,,**/. The photo taken from the SW crater rim on June,.,,**/. The vent is about +/ m across. (Fig. -D) 0,+ +1 (Fig. 2) +* m,- +/ m,**/d 0, ,.+ /.- m s 0,, (Fig. 1) 0,, 0,+ +1 Fig. 1. Fig. 0.. g m, Fig. 0. g m,, g m, + *.*+ km,

11 142 Fig. 3. Grain-size histograms of the,**/ ash-fall deposits from Nakadake crater. *., g m,,**/ 0,+..,.,**/. +,**/ A,**/. +. MB *.3 km. +.,*.+ A 0 +* +,,+ 1,/ D 2 1,* (Malvern Mastersizer S) Fig. 3 +* f (+/+,*,. mm) (+),**/. +., f (+/. mm) f (+/0. +/+,2 mm) 0 +* +,. +. (Md f 0.-) s f (Inman, +3/,),.- 1,/ + f 0 1 f 2 1,* Md f , f (,). +.,*.+ (Md f /./) s f,.0 (-) 0,+ + f (+/, mm) -. f (+/2 +/ +0 mm) (Md f../) -3,**/ + mm. +. 1,/ 2 1,* 0 1 f. +.,*.+ 0,+.,

,**/ 143 Fig. +*. Polarizing microscope photographs of glass shards included in the,**/ ash-fall deposits from Nakadake crater. Photographs A, D, G, J and M are representative of entire sample.

12 ,**/ 143 Fig. +*. Polarizing microscope photographs of glass shards included in the,**/ ash-fall deposits from Nakadake crater. Photographs A, D, G, J and M are representative of entire sample. Arrows in the middle and right photos indicate clear glass shards. Broken circles denote black glassy particles included in the,+ June,**/ ash-fall deposit. Bar of each photo is *.+ mm. +* +/.,. f +*,* (Fig. +*) *.- mm *.. mm

13 144 (Figs. +*B, +*C) (Figs. +*E, +* N) (Fig. +*K) (Fig. +*I),** ,* * +, 3 0,+ +, 1,/ ,* - 2 1,* +*,* 0,+,3 (Fig. +*L) / / +,**- 1 +*,**. + +.,**/,**/. 2,**/,**-,**.,**/,**/. 2 (+) (,),* (-) - (+),**/,,**/ ,**/ m * +, 1,/ 1,/ +., (,) (-) mm +321,**/ 1 3, 1 ; Fig (,),**/. +.,*.+,**/b,**- 1 +*,**. + +.,**/

14 ,**/ ,*.+,**-,**. -*.* +33, ,*.+ +0,**/ + mm + cm,**- 1,**. +,**/ (-),**/ 0,+ +.*,**/.., * Ono et al., +33/ ; +33/ ,-,**/ 0,+ (-) (+) (,),**- 1 +*,**. +* * ph *.1 *.2,**- +* (,**.),**/,**- 1,**. + (Walker, +31-, +32* ; Wright et al., +32*),**/,**/ + +** + +3 km, + mm + +* + mm +**,**/,**- 1,**. +,**/ (Walker, +31-) (Cas and Wright, +321, p.+/0 +/2),**/ /, (+) (,) - ; *. m, (-), (.),**, p. -2,**/ / +*

15 146,**/ +** -** m +,**,/* m,**/ - -,**/,**- 1 +*,**. + +.,**/,**/. +. +/,**/ mm (Fig. -B). +. (Fig. -A) 0 +* +, 1,/. +. 0,+ +** 0,**/ ,**/ ,*.+ -./ km, km,.- km +* * +, 0,+.., 1,/ +.,,**/. 2 (+) (,),* (-) - - (3 +0 ),**/ +. Northern Arizona University Nancy Riggs Cas, R.A.F. and Wright, J.V. (+321) Volcanic Successions, Modern and Ancient. Chapman and Hall, London, /,2p. (+321) +

16 ,**/ 147 (+32* +32.) /* +/,,. (,**,) /1,.*p. (,**/a),** p. (,**/b) +1. 2p. (,**/c) +1. +/,p. (,**/d) p. (,**0),**/ +1,+p. (,**.),**- 1 +* 20 ++, ++1. Inman, D.L. (+3/,) Measures of describing the size distribution of sediments. J. Sediment. Petrol.,,,, +,/ +./. (,**.),**- ++ +,.3./ /*. (,**/) - 0-/p. (,**/).p. (+33-) (+33, ,) //,0.+. (,**/),**- 1 +*,** /*,,1,.+. (,**-) +, 0, 0/. 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, (+33/).* +-- +/+. (,**/),**/ /3. Walker, G.P.L. (+31-) Explosive volcanic eruptions a new classification scheme. Geologische Rundschau, 0,, Walker, G.P.L. (+32*) The Taupo pumice: products of the most powerful known (ultra-plinian) eruption? J. Volcanol. Geotherm. Res., 2, Wright, J.V., Smith, A.L. and Self, S. (+32*) A working terminology of pyroclastic deposits. J. Volcanol. Geotherm. Res., 2, -+/ --0.

熊本大学学術リポジトリ Kumamoto University Repositor Title 阿蘇火山米塚の噴火年代 Author(s) 宮縁, 育夫 Citation 火山, 55(5): Issue date Type URL Right Journal

熊本大学学術リポジトリ Kumamoto University Repositor Title 阿蘇火山米塚の噴火年代 Author(s) 宮縁育夫 Citation 火山 55(5): 219-225 Issue date 2010-10-31 Type URL Right Journal Article http://hdl.handle.net/2298/37047 2010 特定非営利活動法人日本火山学会