Details of the Researcher

PHOTO

Kimiko Taguchi
Section
Graduate School of Science
Job title
Assistant Professor
Degree

  • 博士（理学）（名古屋大学）

  • 修士（理学）（名古屋大学）

Research History 3

  • 2021/04 - 2022/03
    Nagoya University　Graduate School of Environmental Studies Department of Earth and Environmental Sciences

  • 2022/04 - Present
    Tohoku University　Graduate School of Science　Assistant professor

  • 2020/04 - 2021/03
    Nagoya University　Graduate School of Environmental Studies Department of Earth and Environmental Sciences

Education 3

  • Nagoya University　Graduate School of Environmental Studies　Department of Earth and Environmental Sciences

    2018/04 - 2021/03

  • Nagoya University　Graduate School of Environmental Studies　Department of Earth and Environmental Sciences

    2016/04 - 2018/03

  • Nagoya University　School of Science　Department of Earth and Planetary Science

    2012/04 - 2016/03

Professional Memberships 3

  • The Volcanological Society of Japan

    2016/08 - Present

  • American Geophysical Union

    2016/07 - Present

  • Japan Geoscience Union

    2016/02 - Present

Research Interests 1

  • 火山地震学

Research Areas 1

  • Natural sciences / Solid earth science /

Awards 1

  1. 日本火山学会学生優秀論文賞

    2019/05

Papers 5

  1. Oscillation frequencies of long-period seismic events at Kusatsu-Shirane volcano, Japan, related to the volume of water vapour in a hydrothermal crack Peer-reviewed

    Masayuki Nakano, Hiroyuki Kumagai, Kimiko Taguchi

    GEOPHYSICAL JOURNAL INTERNATIONAL　240　(3)　1622-1638　2025/01/23

    DOI： 10.1093/gji/ggaf006 　

    ISSN： 0956-540X

    eISSN： 1365-246X

  2. Temporal evolution of the magmatic system at Nevado del Ruiz Volcano (Colombia) inferred from long-period seismic events in 2003–2020 Peer-reviewed

    Laura Mercado Solórzano, Indira Molina, Hiroyuki Kumagai, Kimiko Taguchi, Roberto Torres, Lina Constanza García Cano, Cristian Mauricio López

    Journal of Volcanology and Geothermal Research　438　107827-107827　2023/05

    Publisher: Elsevier BV

    DOI： 10.1016/j.jvolgeores.2023.107827 　

    ISSN： 0377-0273

  3. Source models of long-period seismic events at Galeras volcano, Colombia Peer-reviewed

    Roberto Torres, Hiroyuki Kumagai, Kimiko Taguchi

    Geophysical Journal International　227　(3)　2137-2155　2021/09/10

    Publisher: Oxford University Press ({OUP})

    DOI： 10.1093/gji/ggab325 　

    ISSN： 0956-540X 1365-246X

    eISSN： 1365-246X

    More details Close

    <title>SUMMARY</title> Long-period (LP) seismic events have occurred repeatedly at Galeras volcano, Colombia, during the transition from effusive dome formation to explosive Vulcanian eruptions. Since 1989, two types of LP events have been observed there: one characterized by long-lasting, decaying harmonic oscillations (NLP events) and the other by non-harmonic oscillatory features (BLP events). NLP events are attributed to resonances of a dusty gas-filled crack in the magma plugging the eruptive conduit. Sixteen episodes of NLP events occurred at Galeras during 1992–2010, each characterized by systematic temporal variations in the frequencies and quality factors of NLP events. Our and previous estimates of crack model parameters during three of those NLP episodes indicate that the similar temporal variations in crack geometry and fluid properties can be explained by an increase in the ash content within the crack and a decrease in crack volume. We found that NLP events, associated with low SO2 fluxes, are anticorrelated with BLP events, which are accompanied by high SO2 emissions. From our observations and analytical results, we inferred that BLP events are generated by resonances of open cracks in the uppermost magma plug, corresponding to tuffisite veins, that efficiently transfer volcanic gases. After sufficient degassing and densification, the magma plug effectively seals the conduit. The growing overpressure in the deeper magma is then released through a shear fracture along the conduit margin. The intrusion of deeper, vesiculated magma into the shear fracture depressurizes and fragments the magma, producing a dusty gas and triggering the crack resonances that generate NLP events. Our results thus indicate that the evolution of the properties of the magma plug controls the occurrences of BLP and NLP events at Galeras. Although NLP events do not always precede explosive eruptions, they indicate that an important overpressure is building in the shallow conduit.

  4. Empirical formula for the quality factors of crack resonances and its application to the estimation of source properties of long-period seismic events at active volcanoes Peer-reviewed

    Kimiko Taguchi, Hiroyuki Kumagai, Yuta Maeda, Roberto Torres

    Geophysical Journal International　224　(3)　2131-2148　2020/10

    Publisher: Oxford University Press ({OUP})

    DOI： 10.1093/gji/ggaa519 　

    ISSN： 0956-540X

    eISSN： 1365-246X

    More details Close

    <title>SUMMARY</title>Long-period (LP) seismic events at active volcanoes are thought to be generated by oscillations of fluid-filled resonators. The resonator geometry and fluid properties of LP sources have been estimated by comparing observed frequencies and quality factors (Q) with those calculated by numerical simulations with a crack model. A method to estimate all the parameters of crack geometry and fluid properties using an analytical formula for crack resonance frequencies has recently been proposed, but this method requires long computational times to compare observed and simulated Q values, especially for LP events with large Q. To resolve this problem, we used numerical simulations to systematically investigate the empirical relation between Q and crack model parameters. We found that Q can be calculated with an empirical formula expressed by the crack width-to-length ratio and the ratio of P-wave velocity in the solid medium to sound speed in the fluid. We applied this formula to LP events at Kusatsu–Shirane volcano, Japan, between 1992 August and 1993 January and at Galeras volcano, Colombia, in 1993 January. Assuming misty gas as the fluid in the crack at Kusatsu–Shirane and dusty gas as the fluid at Galeras, the empirical formula provided more detailed estimates of the parameters than those obtained previously using the Q values estimated in numerical simulations. We then applied the empirical formula to LP events with large Q values observed at Galeras between 2006 December and 2007 January. When we assumed dusty gas as the fluid in the crack, we found decreasing trends in both crack volume and the gas-weight fraction of water vapour in the crack. We also found that the dust volume was proportionally related to the product of crack aperture and crack length or width. These trends and relations were similar to those in 1993 January, suggesting that the LP events at Galeras between 2006 and 2007 were triggered by the explosive fragmentation of intruded magma and the production of a dusty gas, as was previously inferred for the LP events in 1993 January. Welding of ash in the dusty gas and dense magma remaining in the conduit after fragmentation led to a decrease in the source crack size prior to the next LP event. These results demonstrate that our empirical formula for Q can be used to estimate the source properties of LP events with large Q values without requiring long computational times. Use of the formula may thus contribute to improved monitoring of fluid states and understanding of LP triggering processes beneath many volcanoes.

  5. Source Properties and Triggering Processes of Long-Period Events Beneath Volcanoes Inferred From an Analytical Formula for Crack Resonance Frequencies Peer-reviewed

    Kimiko Taguchi, Hiroyuki Kumagai, Yuta Maeda, Roberto Torres

    Journal of Geophysical Research: Solid Earth　123　(9)　7550-7565　2018/09

    Publisher: American Geophysical Union ({AGU})

    DOI： 10.1029/2018jb015866 　

    ISSN： 2169-9313

Presentations 18

  1. Excitation of Long-period (LP) Events at Galeras Volcano, Colombia, Inferred from Crack Model Simulations

    Kimiko Taguchi, Hiroyuki Kumagai, Yuta Maeda, Roberto Armando Torres

    2020 AGU Fall Meeting　2020/12/09

  2. クラック固有振動の数値計算に基づくガレラス山 （コロンビア）での低周波地震の励起過程推定

    田口貴美子, 熊谷博之, 前田裕太, Torres Roberto

    日本火山学会2020年度秋季大会　2020/10/08

  3. 草津白根山で発生したLPイベントの発生過程：水蒸気の凝縮に伴うクラック体積の減少と固有振動の励起

    田口貴美子, 熊谷博之, 前田裕太

    JpGU-AGU Joint Meeting 2020: Virtual　2020/07/14

  4. 光ファイバーケーブルを用いた観測技術 Invited

    田口貴美子

    国際シンポジウム 未来社会のための堅牢なサイバーライフライン　2024/11/21

  5. Amplitude and phase analysis of ground vibration waveform associated with the debris flow observed by the DAS system at Sakurajima volcano

    Kimiko Taguchi, Takeshi Nishimura, Hisashi Nakahara, Takashi Hirose, Haruhisa Nakamichi, Kentaro Emoto, Satoru Hamanaka

    2024/10/17

  6. Analysis of seismograms associated with the debris flow at Sakurajima volcano, Japan, observed by the DAS system

    Taguchi K, Nishimura T, Nakahara H, Hirose T, Emoto K, Hamanaka S, Nakamichi H

    12th EGU Galileo Conference: Fibre Optic Sensing in Geosciences　2024/06/17

  7. Analysis of seismic waveforms associated with the debris flow along the Nojiri River, Sakurajima, on 29 November 2022 observed by the DAS system

    Kimiko Taguchi, Takeshi Nishimura, Hisashi Nakahara, Takashi Hirose, Haruhisa Nakamichi, Kentaro Emoto, Satoru Hamanaka

    2023/10/20

  8. Source properties and scaling relations of volcanic long-period events estimated from crack model and seismic moments

    Japan Geoscience Union Meeting 2022　2022/05/25

  9. 草津白根山で1989-1993年に発生した低周波地震の発生過程

    田口貴美子, 熊谷博之

    日本火山学会2021年度秋季大会　2021/10/20

  10. Empirical Relation for the Quality Factors of Crack Resonances and Its Application to Estimate Source Properties of Volcanic Long-period Seismic Events

    Kimiko Taguchi, Hiroyuki Kumagai, Yuta Maeda, Roberto Armando Torres

    2019 AGU Fall Meeting　2019/12/13

  11. クラック固有振動のQ値と形状・流体特性の関係：経験則の導出と火山性LPイベント解析への応用

    田口貴美子, 熊谷博之, 前田裕太, Torres Roberto

    日本地球惑星科学連合2019年大会　2019/05/28

  12. Triggering Processes of Long-period Seismic Events beneath Volcanoes: Vapor Condensation and Magma Fragmentation in Shallow Cracks

    Kimiko Taguchi, Hiroyuki Kumagai, Yuta Maeda, Roberto Armando Torres

    2018 AGU Fall Meeting　2018/12/10

  13. クラックモデルに基づく周波数解析から推定されるLPイベントの励起過程

    田口貴美子, 熊谷博之, 前田裕太, Torres Roberto

    日本地球惑星科学連合2018年大会　2018/05/22

  14. Resonator size and fluid properties of long-period events inferred from an analytical formula for crack resonance frequencies

    Kimiko Taguchi, Hiroyuki Kumagai, Yuta Maeda, Roberto Armando Torres

    IAVCEI 2017 Scientific Assembly　2017/08/15

  15. LPイベントの振動体サイズおよび流体特性の時間変動：草津白根山とガレラス山の比較

    田口貴美子, 熊谷博之, 前田裕太, Torres Roberto

    日本地球惑星科学連合 連合大会2017年大会　2017/05/22

  16. A simple approach to quantify crack geometry and fluid properties at the long-period seismic source

    Kimiko Taguchi, Hiroyuki Kumagai, Yuta Maeda, Roberto Armando Torres

    2016 AGU Fall Meeting　2016/12/15

  17. クラック振動の解析式に基づくガレラス山（コロンビア）および草津白根山のLPイベントの比較

    田口貴美子, 熊谷博之, 前田裕太, Roberto Torres

    日本火山学会2016年度秋季大会　2016/10/13

  18. クラック振動の解析式を用いたLPイベントの周波数解析に基づく流体特性の推定

    田口貴美子, 熊谷博之, 前田裕太

    日本地球惑星科学連合 連合大会2016年大会　2016/05/25

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Research Projects 4

  1. 火山浅部での低周波地震を励起する熱水やマグマの振動過程の解明と活動監視への応用

    田口 貴美子

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業 若手研究

    Category: 若手研究

    Institution: 東北大学

    2023/04 - 2028/03

  2. Determination of velocity of debris and mudflows by using optical-fibers and distributed acoustic sensing system

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Challenging Research (Exploratory)

    Institution: Kyoto University

    2023/06/30 - 2025/03/31

  3. 超高密度多点地震観測と高精度映像分析による爆発的噴火ダイナミクスの解明

    西村 太志, 中原 恒, 田口 貴美子, 中道 治久, 村田 健史, 長妻 努, 小園 誠史, 江本 賢太郎

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 基盤研究(B)

    Institution: 東北大学

    2022/04/01 - 2025/03/31

  4. 火山性低周波地震の波形解析に基づく発生過程の解明と火山活動監視への応用

    田口 貴美子

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業 特別研究員奨励費

    Category: 特別研究員奨励費

    Institution: 名古屋大学

    2020/04 - 2022/03

    More details Close

    本年度は(1)これまでに考案した火山性低周波地震(long-period (LP) イベント)震源のクラックサイズ・流体特性推定手法を新たに草津白根山で1989-1991年に観測されたLPイベントにも適用したほか、(2)楕円クラックの振動による地震波形の計算に着手した。 (1)で用いた手法では、まず観測波形の周波数スペクトルでみられる複数のピークのうち、一番低次のものに対しクラックの振動パターンを仮定する。そして薄い矩形クラックの振動による地震波形の周波数や減衰率を観測波形のものと比較することで、震源クラックサイズと流体特性を推定する。この手法を適用した結果、今年度新たに解析を行ったイベント震源クラックのサイズと流体特性は前年度までに解析した期間のものと同様に時間変化を示すことが分かった。この結果は国内学会で発表した。 しかし推定されたクラックサイズは観測波形の振幅から推定されるモーメントと整合しないことも明らかになり、これは解析を行う際に仮定したクラックの振動パターンに起因することがわかった。この結果は、より正確に振動体サイズや流体特性を推定し火山浅部の流体の状態のモニタリングに役立てるには、本研究のLPイベント解析手法に地震モーメントの推定も組み込む必要があることを示している。 以上のように本研究で用いる解析手法はLPイベント震源として考えられる流体を含む割れ目を薄い矩形クラックで近似したものであるが、野外で観測される割れ目は端にかけて幅や厚さが狭まるものである。そこで今年度末に、矩形クラックでは一定としていた厚さ方向の大きさを端に向かうほど小さくするプログラムの作成に着手した。来年度の初めにこのプログラムを完成させ、実際に野外で観測される形状の割れ目の振動に対する矩形クラック振動の近似度を調べる予定である。