Bulletin of Volcanology

, Volume 71, Issue 6, pp 619–630 | Cite as

Swelling of a lava plug associated with a Vulcanian eruption at Sakurajima Volcano, Japan, as revealed by infrasound record: case study of the eruption on January 2, 2007

  • Akihiko YokooEmail author
  • Takeshi Tameguri
  • Masato Iguchi
Research Article


In order to clarify the time relation of the expansion of a gas pocket and failure of its overlying plug of lava during Vulcanian eruptions, infrasound records and video images of the Vulcanian eruption that occurred at Sakurajima volcano on January 2, 2007 were analyzed with respect to their origin times. Weak (≤3 Pa) and slowly increasing air pressure preceded the impulsive compression phase by 0.25–0.32 s, and a longer-period rarefaction phase of infrasound waves was recognized at all microphone stations. The velocity of the compression phase was assumed to be supersonic (ca. 400 m/s) up to 850 m above the crater bottom from other recent explosions. On the other hand, the propagation velocity of the preceding weak signal was regarded to be similar to the air sound velocity because the lack of impulsiveness is unlikely to be related to the main compression phase. Therefore, the estimated origin time of the main compression phase was delayed by 0.5–0.7 s from the preceding phase. The origin time of the preceding phase coincided with the onset of the isotropic expansion process of the pressurized gas pocket, which was obtained by the waveform inversion of the explosion earthquake. In contrast, the origin time of the main impulsive phase coincided with the time when the expansion rate reached its peak. This observation suggests that the volumetric increase of the gas pocket caused swelling of the surface of the crater bottom and its subsequent failure. When the expansion velocity exceeded a threshold level, the main impulsive compression phase radiated with a high velocity by the sudden releases of the pressurized gases. The volumetric change at the source was estimated to be 280–560 m3 from the preceding phase of the infrasound. This volume change indicates that the vertical displacement of the swelling ground was on the order of 1.0 m, assuming the radius of the lava plug was ca. 10 m.


Sakurajima volcano Vulcanian eruption Infrasound wave 



The authors are grateful to all stuff members of SVO for their helpful support, especially to K. Ishihara for providing many constructive comments and fruitful suggestions. We also appreciate the Ministry of Land, Infrastructures and Transport Japan, Kokusai Kogyo, Co., Ltd. and Kagoshima Local Meteorological Observatory for providing data of the ARM microphone, the DEM data, and aerological weather data, respectively. Setup, maintenance, and operation of the KUR camera were supported by NHK (Japan Broadcast Association) and Y. Tashiro. Two reviewers, M. Ichihara and E. Marchetti, are thanked for constructive criticisms that much improved this manuscript. This work was financially supported by the 21st COE program for DPRI, Kyoto University (No. 14219301), Grant-in-Aid for Scientific Research (Nos. 14080203 and 18740277), and JSPS Research Fellowships for Young Scientists (No. 19·126).


  1. Garcés MA (1997) On the volcanic waveguide. J Geophys Res 102:22,547–22,564Google Scholar
  2. Garcés MA, Hansen RA (1998) Waveform analysis of seismoacoustic signals radiated during the fall 1996 eruption of Pavlof Volcano, Alaska. Geophys Res Lett 25:1051–1054CrossRefGoogle Scholar
  3. Garcés MA, Hansen RA, Lindquist KG (1998) Travel times for infrasonic waves propagating in a stratified atmosphere. Geophys J Int 135:255–263CrossRefGoogle Scholar
  4. Gresta S, Ripepe M, Marchetti E, D’Amico S, Coltelli M, Harris AJL, Privitera E (2004) Seismoacoustic measurements during the July-August 2001 eruption of Mt. Etna volcano, Italy. J Volcanol Geotherm Res 137:219–230. doi: 10.1016/j.jvolgeores.2004.05.017 CrossRefGoogle Scholar
  5. Iguchi M (1994) A vertical expansion source model for the mechanisms of earthquakes originated in the magma conduit of an andesitic volcano: Sakurajima, Japan. Bull Volcanol Soc Jpn 54:161–186Google Scholar
  6. Iguchi M, Ishihara K (1990) Comparison of earthquakes and air-shocks accompanied with explosive eruptions at Sakurajima and Suwanosejima Volcanoes (in Japanese with English Abstract). Ann Disas Prev Res Inst 33B:1–12Google Scholar
  7. Iguchi M, Yakiwara H, Tameguri T, Hendrasto M, Hirabayashi J (2007) Mechanism of explosive eruption revealed by geophysical observations at the Sakurajima, Suwanosejima and Semeru Volcanoes. J Volcanol Geotherm Res. doi: 10.1016/j.jvolgeores.2007.10.010
  8. Ishihara K (1985) Dynamic analysis of volcanic explosion. J Geodyn 3:327–349CrossRefGoogle Scholar
  9. Ishihara K (1990) Pressure sources and induced ground deformation associated with explosive eruptions at an andesitic volcano: Sakurajima volcano, Japan. In: Ryan M (ed) Magma transport and storage. Wiley, New York, pp 335–356Google Scholar
  10. Johnson JB (2005) Source location variability and volcanic vent mapping with a small-aperture infrasound array at Stromboli Volcano, Italy. Bull Volcanol 67:1–14. doi: 10.1007/s00445-004-0356-8 CrossRefGoogle Scholar
  11. Kanamori H, Given JW, Lay T (1984) Analysis of seismic body waves excited by the Mount St. Helens eruption of May 18, 1980. J Geophys Res 89:1856–1866CrossRefGoogle Scholar
  12. Kato K, Oshima H, Sasatani T, Ichiyanagi M, Takahashi H, Goto A, Aoyama H (1999) 7. Report about geophysical measurements (in Japanese). In: Taniguchi H (ed) 98’ Research project on the measurement of volcanic explosions, pp 30–45Google Scholar
  13. Lighthill J (1978) Waves in fluids. Cambridge Press, New YorkGoogle Scholar
  14. Minakami T, Utibori S, Hiraga S, Miyazaki T, Gyoda N, Utunomiya T (1970) Seismometrical studies of volcano Asama, Part I. seismic and volcanic activities of Asama during 1934–1969. Bull Earthq Res Inst 48:253–301Google Scholar
  15. Ohminato T, Takeo M, Kumagai H, Yamashina T, Oikawa J, Koyama E, Tsuji H, Urabe T (2006) Vulcanian eruptions with dominant single force components observed during the Asama 2004 volcanic activity in Japan. Earth Planets Space 58:583–593Google Scholar
  16. Ripepe M, Marchetti E (2002) Array tracking of infrasonic sources at Stromboli Volcano. Geophys Res Lett 29:L2076. doi: 10.1029/2002GL015452 CrossRefGoogle Scholar
  17. Ripepe M, Ciliberto S, Scheava MD (2001) Time constrains for modeling source dynamics of volcanic explosions at Stromboli. J Geophys Res 106:8713–8727CrossRefGoogle Scholar
  18. Ripepe M, Harris AJL, Carniel R (2002) Thermal, seismic and infrasonic evidences of variable degassing rates at Stromboli Volcano. J Volcanol Geotherm Res 118:285–297CrossRefGoogle Scholar
  19. Rowe CA, Aster RC, Kyle PR, Dibble RR, Schlue JW (2000) Seismic and acoustic observations at Mount Erebus Volcano, Ross Island, Antarctica, 1994–1998. J Volcanol Geotherm Res 101:105–128CrossRefGoogle Scholar
  20. Ruiz MC, Lee JM, Johnson JB (2007) Source constraints of Tungurahua Volcano explosion events. Bull Volcanol 68:480–490CrossRefGoogle Scholar
  21. Sakai T, Churei M, Yoshida A (2001) Existence of preceding phase in waveforms of air-shocks accompanying explosive eruptions at Sakurajima Volcano and Karymsky Volcano (in Japanese). Abstr Volcanol Soc Japan, A16Google Scholar
  22. Stix J, Torres RC, Narváez LM, Cortés GPJ, Raime JA, Gómez DM, Castonguay R (1997) A model of vulcanian eruptions at Galeras volcano, Colombia. J Volcanol Geotherm Res 77:285–303CrossRefGoogle Scholar
  23. Tameguri T, Iguchi M, Ishihara K (2002) Mechanism of explosive eruption from moment tensor analysis of explosion earthquakes at Sakurajima Volcano, Japan. Bull Volcanol Soc Jpn 49:197–215Google Scholar
  24. Uhira K, Takeo M (1994) The source of explosive eruption of Sakurajima Volcano, Japan. J Geophys Res 99:17,759–17,789Google Scholar
  25. Vergniolle S, Brandeis G (1996) Strombolian explosions. 1 A large bubble breaking at the surface of a lava column as a source of sound. J Geophys Res 101:20,433–20,448Google Scholar
  26. Vergniolle S, Brandeis G, Mareschal JC (1996) Strombolian explosions 2. Eruption dynamics determined from acoustic measurements. J Geophys Res 101:20,449–20,466Google Scholar
  27. Vergniolle S, Boichu M, Caplan-Auerbach J (2004) Acoustic measurements of the 1999 basaltic eruption of Shishaldin Volcano, Alaska 1. Origin of Strombolian activity. J Volcanol Geotherm Res 137:109–134. doi: 10.1016/j.jvolgeores.2004.05.003 CrossRefGoogle Scholar
  28. Yokoo A, Ishihara K (2007) Analysis of pressure waves observed in Sakurajima eruption movies. Earth Planets Space 59:177–181Google Scholar

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Akihiko Yokoo
    • 1
    Email author
  • Takeshi Tameguri
    • 1
  • Masato Iguchi
    • 1
  1. 1.Sakurajima Volcano Research Center, Disaster Prevention Research InstituteKyoto UniversityKagoshimaJapan

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