Bulletin of Volcanology

, Volume 70, Issue 9, pp 1031–1042 | Cite as

Characteristics of isolated hybrid tremor (HBT) during a calm activity period at Aso Volcano

  • Takehiko MoriEmail author
  • Yasuaki Sudo
  • Tomoki Tsutsui
  • Shin Yoshikawa
Research Article


Isolated-type tremors having two events with different dominant frequencies are characteristic seismological phenomena observed during the fumarolic activity stage at Aso Volcano. These isolated tremors are called hybrid tremors (HBT) and comprise two parts: an initial part named the “HF-part” with a dominant frequency in the high-frequency region (approximately 10 Hz) and the following part named the “LF-part” with a dominant frequency in the low-frequency region (approximately 2 Hz). The LF-part is observed after the HF-part, and the HBT is accompanied by a long-period tremor (LPT). Hypocenters and source parameters are estimated using seismograms recorded at 64 stations around Nakadake crater. The amplitude distributions of all HF-parts have almost similar trends. Similarly, the amplitude distributions of all LF-parts have almost similar trends. However, the amplitude distributions of HF- and LF-parts are not similar. From these results, we proposed that the hypocenters and source parameters of HF- and LF-parts are not common, but each of them have common hypocenters and source parameters. The hypocenter region of HF-parts was estimated to be just beneath the fumarole region south of the 1st crater: the volume fluctuation is the major source factor. The hypocenter region of LF-parts is estimated to be at a depth of approximately 300 m beneath the first crater: the strike–slip component is the major source parameter. The hypocentral depth of LF-parts is located at the upper end of the crack estimated to be the source of the LPTs. The LPTs and HBTs are observed almost simultaneously. We consider that volcanic fluid is involved in the source mechanisms of both HBT and LPT.


Aso Volcano ASO98 experiment Fumarolic activity Volcano seismology Isolated-type tremor Hybrid tremor Volcanic fluid 



We are grateful to the staff members of the Aso Volcanological Laboratory, Kyoto University. We also thank Drs. J. Hirabayashi and K. Nogami of the Volcanic Fluid Research Center, Tokyo Institute of Technology, for their support. The authors are indebted to the thoughtful and helpful comments from Dr. A. W. Hurst of GNS, New Zealand; Drs. K. Ishihara and M. Iguchi, Sakurajima Volcano Research Center, Kyoto University; and Dr. H. Shinohara, Geological Survey of Japan, AIST. We would like to thank Dr. E. Marchetti, Dr. M. Ripepe, and two anonymous reviewers for their constructive comments. The data used in this study were obtained from the National Project for Prediction of Volcanic Eruptions (Project ASO98). We also thank all the members of Project ASO98.


  1. Brace WF, Paulding BW, Scholz C (1966) Dilatancy in the fracture of crystalline rocks. J Geophys Res 71:3939–3953Google Scholar
  2. Chouet B, Saccorotti G, Dawson P, Martini M, Scarpa R, DeLuca G, Milana G, Cattaneo M (1999) Broadband measurements of the sources of explosions at Stromboli Volcano, Italy. J Geophys Res 102:15129–15150CrossRefGoogle Scholar
  3. Fujita E, Ida Y, Oikawa J (1995) Eigen oscillation of a fluid sphere and source mechanism of harmonic volcanic tremor. J Volcanol Geotherm Res 69:365–378CrossRefGoogle Scholar
  4. Hase H, Hashimoto T, Sakanaka S, Kanda W, Tanaka Y (2005) Hydrothermal system beneath Aso volcano as inferred from self-potential mapping and resistivity structure. J Volcanol Geotherm Res 143:259–277CrossRefGoogle Scholar
  5. Hurst AW (1992) Stochastic simulation of volcanic tremor from Ruapehu. J Volcanol Geotherm Res 51:185–198CrossRefGoogle Scholar
  6. Japan Meteorological Agency (2005) National catalogue of the active volcanoes in Japan (Third edition). Japan Meteorological Agency, pp 1–635, (in Japanese)Google Scholar
  7. Kaneshima S, Kawakatsu H, Matsubayashi H, Sudo Y, Tsutsui T, Ohminato T, Ito H, Uhira K, Yamasato H, Oikawa J, Takeo M, Iidaka T (1996) Mechanism of phreatic eruptions at Aso volcano inferred from near-field broadband seismic observations. Science 273:642–645CrossRefGoogle Scholar
  8. Kawakatsu H, Ohminato T, Ito H, Kuwahara Y (1992) Broadband seismic observation at Sakurajima Volcano, Japan. Geophys Res Lett 19:1959–1962CrossRefGoogle Scholar
  9. Kawakatsu H, Ohminato T, Ito H (1994) 10s period volcanic tremors observed over a wide area in southwestern Japan. Geophys Res Lett 21:1963–1966CrossRefGoogle Scholar
  10. Kawakatsu H, Kaneshima S, Matsubayashi H, Ohminato T, Sudo Y, Tsutsui T, Uhira K, Yamasato H, Ito H, Legrand D (2000) Aso94: Aso seismic observation with broadband instruments. J Volcanol Geotherm Res 101:129–154CrossRefGoogle Scholar
  11. Kikuchi S (1962) On the short period volcanic micro-tremors at Mt. Aso. Bull Volcanol Soc Jpn 7:1–16, (in Japanese)Google Scholar
  12. Kubotera A (1974) In: Civetta L, Gasparini P, Luongo G, Rapolla A (eds) Volcanic tremors at Aso volcano. Physical Volcanology, Elsevier, pp 29–47Google Scholar
  13. Kuwahara Y, Itoh H, Kawakatsu H, Ohminato T, Kiguchi T (1997) Crustal heterogeneity as inferred from seismic coda wave decomposition by small-aperture array observation. Phys Earth Planet Inter 104:247–256CrossRefGoogle Scholar
  14. Legrand D, Kaneshima S, Kawakatsu H (2000) Moment tensor analysis of near-field broadband waveforms observed at Aso Volcano, Japan. J Volcanol Geotherm Res 101:155–169CrossRefGoogle Scholar
  15. Miller AD, Stewart RC, White RA, Luckett R, Baptie BJ, Aspinall WP, Latchman JL, Lynch LL, Voight B (1998) Seismicity associated with dome growth and collapse at the Soufriere Hills Volcano, Montserrat. Geophys Res Lett 25:3401–3404CrossRefGoogle Scholar
  16. Mori T, Notsu K (1997) Remote CO, COS, CO2, SO2, HCl detection and temperature estimation of volcanic gas. Geophys Res Lett 24:2047–2050CrossRefGoogle Scholar
  17. Mori T, Mori T, Kazahaya K, Ohwada M, Hirabayashi J, Yoshikawa S (2006) Effect of UV scattering on SO2 emission rate measurements. Geophys Res Lett 33:L17315CrossRefGoogle Scholar
  18. Neidel N, Tarner MT (1971) Semblance and other coherency measures for multichannel data. Geophysics 36:483–497CrossRefGoogle Scholar
  19. Ono H, Hoka T (1984) Seismic activity near the Nakadake, Volcano Aso in 1981. Joint Geophysical and Geochemical Observations of Aso Volcano: 7–16, (in Japanese)Google Scholar
  20. Ono K, Watanabe K (1985) Geological map of Volcanoes 4; Geological map of Aso Volcano 1: 50000. Geological survey of Japan, Tsukuba, (in Japanese)Google Scholar
  21. Sassa K (1935) Volcanic micro-tremors and eruption-earthquakes (part 1 of the geophysical studies on the Volcano Aso). Mem Coll Sci Kyoto Univ 18:255–293Google Scholar
  22. Seidl D, Kirbani SB, Brüstle W (1990) Maximum entropy spectral analysis of volcanic tremor using data from Etna (Sicily) and Merapi (central Java). Bull Volcanol 52:460–474CrossRefGoogle Scholar
  23. Shima M (1958) On the second volcanic micro-tremor at the Volcano Aso. Disaster Prevent Res Inst Kyoto Univ Bull 22:1–6Google Scholar
  24. Shimizu H, Ueki S, Koyama J, Takagi A (1984) Mechanisms of volcanic earthquakes following the 1983 eruption of Miyakejima. Bull Volcanol Soc Jpn 29:S81–S100, (in Japanese)Google Scholar
  25. Sudo Y, 89 persons (2002) 1998 seismic exploration, Aso98, in Aso Volcano. Bull Earthq Res Inst 77:303–336Google Scholar
  26. Takagi N, Kaneshima S, Kawakatsu H, Yamamoto M, Sudo Y, Ohkura T, Yoshikawa S, Mori T (2006) Apparent migration of tremor source synchronized with the change in the tremor amplitude observed at Aso volcano, Japan. J Volcanol Geotherm Res 154:181–200CrossRefGoogle Scholar
  27. Tanaka Y (1994) Eruption mechanism as inferred from geomagnetic changes with special attention to the 1989–1990 activity of Aso Volcano. J Volcanol Geotherm Res 56:319–338CrossRefGoogle Scholar
  28. Tsutsui T, Sudo Y (2004) Seismic reflectors beneath the central cones of Aso Volcano, Kyushu, Japan. J Volcanol Geotherm Res 131:33–58CrossRefGoogle Scholar
  29. Yamamoto M, Kawakatsu H, Kaneshima S, Mori T, Tsutsui T, Sudo Y, Morita Y (1999a) Detection of a crack-like conduit beneath the active crater at Aso Volcano, Japan. Geophys Res Lett 26:3677–3680CrossRefGoogle Scholar
  30. Yamamoto M, Kawakatsu H, Kaneshima S, Iidaka T, Oikawa J, Watada S, Morita Y, Mori T, Tsutsui T, Sudo Y, Yoshikawa S, Hashimoto T, Nakaboh M (1999b) ASOBOI97: Aso Seismic Observation with Broadband Instruments in 1997. Bulletin of the Earthquake Research Institute 74:267–285Google Scholar
  31. Yoshikawa S, Kitsunezaki C (1959) On the short period volcanic micro-tremors at volcano Aso. Bull Volcanol Soc Jpn 3:147–153, (in Japanese)Google Scholar
  32. Yoshikawa S, Sudo Y (2004) Volcanic activity and surface temperature variation of crater lake in Naka-dake crater at Aso volcano. Annuals of Disas Prev Res Inst Kyoto Univ 47:803–807, (in Japanese)Google Scholar

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Takehiko Mori
    • 1
    Email author
  • Yasuaki Sudo
    • 2
  • Tomoki Tsutsui
    • 3
  • Shin Yoshikawa
    • 4
  1. 1.Geological Survey of JapanNational Institute of Advanced Industrial Science and TechnologyIbarakiJapan
  2. 2.The Foundation of Aso Volcano MuseumKumamotoJapan
  3. 3.Faculty of Engineering and Resource ScienceAkita UniversityAkitaJapan
  4. 4.Aso Volcanological Laboratory, Graduate School of ScienceKyoto UniversityKumamotoJapan

Personalised recommendations