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Impact Crater Distribution Map of the Eruption of Asama Volcano on
September +, ,**. Using High-resolution Satellite Imagery
Hisashi SASAKI῍ and Sakae MUKOYAMA῍
Asama volcano erupted on September +, ,**., and volcanic bombs, lapilli, and volcanic ash were ejected.
The distribution of the volcanic bombs was investigated by using IKONOS high-resolution satellite imagery.
IKONOS imagery with one-meter ground resolution enabled us to identify the distribution of the impact craters
greater than three meters in diameter. Many impact craters are distributed northwestward, according to the
distribution density chart of the impact craters. The crater shape of Asama volcano was analyzed by using DEM
created from airborne laser scanner data, and the result shows that there is no obstruction in the crater area toprevent volcanic bombs to be projected at an angle of 0- degree that gives the maximum attainment distance(Iguchi et al., +32-). It suggests that the shape of the crater did not a#ect the distribution pattern of the impact
craters. The outline of the eruption can be understood based on the distribution pattern of the impact craters
larger than three meters in diameter, which can be interpreted from IKONOS imagery.
Key words : Asama volcano, impact crater, high-resolution satellite imagery, remote sensing/@[0"+ῌ ῐ ῎ ῑ ῏,**.  3+  ,*  *,       !" # +32- $ ,+ %&'( ) ! *#+ ,-.

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Kokusai Kogyo Co., Ltd., RICH11BLDG, +ῌ-*,North1 West1, Kita-ku, Sapporo *0*ῌ*2*1, Japan
Corresponding author : Hisashi Sasaki
e-mail : hisashi_sasaki@kkc.co.jp

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65Fig. ,. Contour map of the top part of Asama volcano before the eruption based on the airborne laser scanner
DEM. It was acquired in August ,**,. The contour interval is / m. The surface altitude is displayed inrainbow color, and superimposed on the contour lines.

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66

Fig. -. IKONOS imagery of Asama volcano. (a) True color imagery of Asama volcano after the eruption on
September +, ,**.. (b) True color imagery of an area on the slope of Asama volcano, which is about +., km
northwest of the crater, before the eruption. It was acquired on September ,., ,**,. (c) True color imageryof the same area as (b) after the eruption on September +, ,**.. The data acquisition date is September +/,,**.. Red circle on the images indicates the typical impact crater. Blue circle on the images indicates theray caused by volcanic bombs.
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67

Fig. .. IKONOS imagery of the northwestern side of Asama volcano. The date of acquisition is September +/,,**.. (a) True color imagery. (b) False color imagery. Circles on the images indicate forest ﬁre areas.

 .  !IKONOS ,**.  3  +/  (a) 
 "#$% & (b)Fig. /. IKONOS imagery of the south side of Asama volcano. The data acquisition date is September +/, ,**..
(a) True color imagery. (b) False color imagery. Note that the degree of transparency of the volcanic smoke
shown in the left image is di#erent from that in the right image. Red circles on the images indicate theimpact crater.

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Fig. 0. A distribution map of the impact craters formed by the volcanic bombs ejected during the eruption of
Asama volcano on September +, ,**., based on the interpretation of IKONOS imagery. Hatched area was
not analyzed. IKONOS imagery enabled us to identify the impact craters greater than three meters indiameter.

~ 0 X+, ,**.  3  +  HIJWo~ ^. / 7l3 X y - m -HIJW X,¸¹ º»+ ¼

70

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Fig. 1. Azimuthal density distribution of impact craters. This ﬁgure shows the number of impact craters in eachdirection within the radial region between *.1 km and +./ km from the center of the crater.

 1tu,v ° 5 ±) *.1 km >±) +./ km ²b;³´ ° tu,vµ;¶·45e£),-$»¼& ,**. F 3 G + H=;23456
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71

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