Precedent Phase of S Wave Observed in Kuju Volcano
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- TANAKA Maki
- Aso Volcanological Laboratory, Kyoto University
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- SUDO Yasuaki
- Aso Volcanological Laboratory, Kyoto University
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- TSUTSUI Tomoki
- Aso Volcanological Laboratory, Kyoto University:(Present)Faculty of Engineering and Resource Science, Akita University
Bibliographic Information
- Other Title
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- 九重火山で観測されたS波の先行相
- クジュウ カザン デ カンソク サレタ Sハ ノ センコウソウ
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Abstract
Kuju Volcano is located in the center of Kyushu Island, Japan. This volcano is a complex volcano formed of andesitic lava domes. A small phreatic eruption occurred at the northeastern side of Mt. Hossho in the center region of the volcano on October 1995. Since then, a seismic network has been installed in this area. Clear precedent phases of S wave are found in many seismograms recorded by the network. Precedent phases show following features; 1) the arrival time difference between the precedent phase and S wave is independent of hypocenteral distance, 2) the phase is significant in a vertical component, 3) the amplitude of the phase is lager than that of P wave, 4) the phase appears for the case of which the seismic station is situated in the direction of relatively large amplitude of S wave from hypocenter. Because of these features, their precedent phases are concluded to be S-P converted phase which is excited in the boundary of S wave velocity. Conversion points distributed within the depth of 0.5 km to 1.5 km from the surface beneath the western region of Kuju Volcano, which are estimated by means of a travel time analysis. Conversion points correspond to a clear boundary of elastic velocity in well data which were obtained around this area.
Journal
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- BULLETIN OF THE VOLCANOLOGICAL SOCIETY OF JAPAN
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BULLETIN OF THE VOLCANOLOGICAL SOCIETY OF JAPAN 45 (2), 65-73, 2000
The Volcanological Society of Japan
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Details 詳細情報について
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- CRID
- 1390282679280895104
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- NII Article ID
- 110003041182
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- NII Book ID
- AN10512786
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- ISSN
- 21897182
- 04534360
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- NDL BIB ID
- 5342866
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- Text Lang
- ja
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- Data Source
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- JaLC
- NDL
- CiNii Articles
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- Abstract License Flag
- Disallowed