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Volcanic activity of Sakurajima volcano, South Kyushu, Japan
Masato Iguchi
Sakurajima Volcano Research Center, DPRI, Kyoto Univ.
2012/5/18
Sakurajima
Unzen
Aso
32N
30N
130E
132E
Satsuma-Iwojima
Suwanosejima
Volcanoes in Kyushu
Kirishima Volcano Complex
Kaimondake
Kuchinoerabujima
Nakanoshima
110 volcanoes in Japan
Japan Sea
Russia
Japan
Korea
Pacific Ocean
2011 Eruption at Shin-moedake of Kirishima Volcano Complex
Mr. Shimousuki, Kagoshima International Aviation
Deflation due to sub-plinian eruption
on January 26, 2011
Quick turn to inflation inflation
Slope distance change
Sub-plinian eruption on January 26, 2011 Lava dome
Historical eruption of Sakurajima
1914
1914
1779
1779
1471-76
1471-76
1946
764
764
1471-
1476
1779
1914
500
1000
1500
2000
AD 0
Minamidake
Kitadake
Showa crater
Submarine eruption
in 1780
Historical eruptions
Bunmei
eruption
An’ei
eruption
Taisho
eruption
Showa
eruption
1471-76 1779-80 1914 1946
Vent location NE-SW N-S E-W E
Volume of
lava (km3)
0.5 1.7 1.34 0.18
Volume of
tephra (km3)
0.7 0.4 0.52 0.02
Plume height unknown 12,000m 8,000m 2,000m
Casualties many 163 58 1
VEI 5
Eruption in 1779 Eruption in 1914
Eruptive activity of Sakurajima
Showa crater
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
0
1000
2000
3000
1977年 以 前 は 測 定 なし
火山灰量(万トン)
年間爆発回数
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
0
200
400
600
800
1000 南岳爆発回数 昭和火口爆発回数
2012年
3月まで
Annual number of explosion
Minamidake crater
Annual weight of volcanic ash
(million ton)
30
20
10
No measurement before 1977
1/1 4/1 7/1 10/1 1/1 4/1 7/1 10/1 1/1 4/1 7/1 10/1 1/1 4/1 7/1 10/1 1/1 4/1
0
50
100
150
200
250
300
空気
振動
振幅
(Pa)
1/1 4/1 7/1 10/1 1/1 4/1 7/1 10/1 1/1 4/1 7/1 10/1 1/1 4/1 7/1 10/1 1/1 4/1
0
20
40
60
80
100
120
140
160
180
200
月別爆発回数
2008 2009 2010 2011 2012
0
500
1000
1500
2000
2500
3000
3500 積算回数
積算回数
Increase in eruptive activity The first explosion on
February 3, 2008
Increase in
eruptivity
Increase in
eruptivity
April 9, 2009
Pyroclastic flow
Explosion at Minamidake
October 3, 2009
Lava dome in crater
JMA
Month
ly n
um
ber
of explo
sio
n
Cum
ula
tive n
um
ber
Showa
Enlargement of Showa crater
May 2007
Jan 2006 Minamidake
Showa
Minamidake
Showa
Minamidake
Before eruptive activity
Sep 2011
350m
5
10
15
20km
霧島
鹿児島市
姶良カルデラ
桜島
マグマ溜り1× 107m3/年
5
10
15
20km
霧島
鹿児島市
姶良カルデラ
桜島
マグマ溜り1× 107m3/年
1974-1992 (Vulcanian eruption) Since 1993 (Less eruptivity)
Magma discharge Magma accumulation
Magma supply system of Sakurajima
Aira caldera
Sakurajima
Aira caldera
Sakurajima
Supply rate 1x107m3/year
Supply rate 1x107m3/year
Eruptive activity at Showa crater has not decreased magma in the reservoir yet.
Magma reservoir Magma reservoir
Location of VT earthquakes
10
5
0
0 5 102012/2/21
2012/2/21
2010/7
2010/7
N
5km
M 0 1 2
1997-2010 (N=548)
2010/7 M
W
W
Depth (km)
Depth
(km
)
M
Jan 12, 1914 M7.1
Magma reservoir
Aseismic zone
Long-term vertical displacement
1914 eruption
1946 eruption
Violent explosivity of Minamidake
Volcanic ash (200 million tons) ejected from1974 to 1992
31 years
28 years
30 years?
Inflation since 1993
Aira caldera
Recent inflation of Sakurajima measured by GPS
SVOG KURG
ARIG
FUTG
Minamidake Showa crater
1995199619971998199920002001200220032004200520062007200820092010201120120.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14199519961997199819992000200120022003200420052006200720082009201020112012
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0
40
80
120
160
200
240
0
40
80
120
160
200
240
爆発回数
桜島横山町-黒神町(東西)
京都大学防災研究所
G PS連続観測による水平地盤変動
水平
変動
(m)
有村町-桜島二俣町(南北)
火山灰量
Horizonta
l dis
pla
cem
ent
(m)
FUTG-ARIG(N-S)
KURG-SVOG(E-W)
Volcanic ash
Number of explosion
Ballistics
Sakurajima
Minamidake
Showa crater
3.5km
2km
South foot, Jul 21, 1985
Influence of volcanic ash fall
Thickness of ash fall deposit by 1914 eruption
Range of ash fall
(Omori, 1916)
Many mud flows occurred after the 1914 eruption
Mud flow (Minamidake eruption)
Dispersion of volcanic ash from Sakurajima volcano in 1914
(Omori, 1916)
Haneda
Narita
Kagoshima
Nagoya
Itami
Kansai
Fukuoka
Airport
20km
10km
5km City hall
Prefecture
government
Tarumizu city
Kirishima city
Kanoya city
Sakurajima
Aira city
Kagoshima city
Hioki city
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