IUGONET workshop(18 Aug. 2015)

GNSS-TECで見る、最近の火山噴火に伴う電離圏擾乱

北海道大学 宇宙測地学研究室
中島 悠貴、日置幸介

Acoustic/gravity wave
Ionosphere

How does an eruption disturb
the ionosphere?

Troposphere(Neutral atmosphere)

GNSSSatellite

e-ee-e-f1
Stationf2

e-ee-ee-

Ionosphere

TEC (Total Electron Content)# electrons along the line-of-sight2004 Asamayama(Heki 2006)

Vulcanian2009 Sakurajima
2011 Shinmoe-dake2003 Soufriere Hills(Dautermann et al. 2009)

Plinian2014 Kelud

Vulcanian vs. Plinian

TEC signatures: Vulcanian vs. PlinianType 1Type 2Plinian eruptions excite atmospheric resonance

The 2004
Asama volcanoEruption

SIP(Sub Ionospheric Points)

StationSeismometer 4.3mHz

3.7mHzTwo frequency peaks: 270 sec (3.7 mHz)
230 sec (4.3 mHz)Near Field Ionospheric Disturbanceby the Eruption of the Kelud Volcano,Indonesia, in February 2014
Observed by GNSS-TEC

 Kelud Volcano eruption in 2014

Java, Indonesia

VEI (Volcanic Explosivity Index) : 4
http://guardianlv.com/2014/02/indonesia-volcano-culture/Trip to the Kelud (1 Aug.)
Prof. Heki Dr. Cahyadi

Trip to the Kelud (1 Aug.)VEI = Volcanic Explosivity Index

VEI
km3
410-1
310-2
210-3
110-5
1900

1919

2014
The dome
collapsed.
2007
A dome
grew.

1920

1940

1960

1980

2000

Year

The Smithsonian Institution's Global Volcanism ProgramKelud Volcano Feb 13, 2014 Explosion
BeforeAfter

http://www.wired.com/2014/02/kelud-eruption/

Rayleigh wave
→ Solid Earth Event ?

Acoustic wave
→ Explosion ?

Plinian eruption ?
(acoustic wave)

and: GPS & GLONASS (30 sec)
: GPS (15 sec)

explosion

TEC Change (TECU)

continuous eruption

270 sec period components
extracted with wavelet

Ionospheric
Piercing
Pointe-ee-e-ee-e-ee-

f1
Station

f2

250km
Sub
IonosphericPoint

Distance from Kelud (km)dTEC (TECU)〜1.0 km/s(Acoustic Velocity
in the ionosphere)4.6mHz

3.7mHz

GNSS-TEC

Seismogram
4.7mHz3.7mHzKeludAnalyzed by Dr. Takeo

200-300 sec
100-200 sec

Ash Supply to Plume
15:54 – 17:56 (Ishii et al. 2014)

Seismometer (15-30 sec)
Seismometer (200-300 sec)
IonosphereLeaking

Explosion

Vent
expansion

15:00

16:00

Plinian
Eruption

Coupling

17:00

18:00

19:00

http://www.wired.com/2015/04/chiles-calbuco-unleashes-dramatic-explosive-eruption/
Photo by JULIO DEL RIO C.

・An eruption from Calbuco began at
21:04 UT on 22 April. […] After a Large
seismic event detected at 20:35 UT, a 90
minute eruption generated a sub-Plinian,gray ash plume that rose 15 km above themain crater….
・A large second event on 23 April began
at 4:00 UT, lasted six hours, and also
generated a sub-Plinian ash plume thatrose higher than 15 km….
The Smithsonian Institution's Global Volcanism Program –Weekly Reports
http://www.volcano.si.edu/volcano.cfm?vn=358020

Airglow observed by Suomi NPP

11.45 µm
https://cimss.ssec.wisc.edu/goes/blog/archives/1817
4

21lhcl1120.15o

20

22Time (UT)23

GNSS Stations:
RAMSAC and IGS

Sat6
Sat9
Sat23
Sat10
Sat26
Sat1
Sat7
Sat3
Sat19
Sat17
Sat14
Sat31
Sat4
Sat32
Sat1124

Earthquake

22 April.

First Eruption

Second Eruption

23 April.

23 April.

Summary: the 2015 Calbuco case
 Ionospheric disturbances are detected
near the Calbuco volcano after theeruptions.
 These excitations correspond to the twoeruptions.
 Second excitation continued for morethan 5 hours.
 Frequency components have atmosphericeigenfrequency components.

GEONET(Japanese GNSS Dense Array)http://www.bosai.go.jp/saigai/2015/pdf/20150529_0
1.pdf

Barogram