Waveform inversion for the P wave velocity structure in the outermost core

• Project/Area Number: 18K03797
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17040:Solid earth sciences-related
• Research Institution: The University of Tokyo
• Principal Investigator: Kawai Kenji 東京大学, 大学院理学系研究科(理学部), 准教授 (20432007)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000); Fiscal Year 2020: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2018: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
• Keywords: 波形インバージョン / 核・マントル境界 / 最外核 / 液体 / マントル / 外核 / 広帯域地震波形 / 固体液体境界 / 異方性 / アレイ観測網 / 震源パラメータ / 震源再決定 / 短周期 / 地震波形インバージョン / マントル最下部 / 軽元素

Outline of Final Research Achievements

To infer the P-wave velocity structure of the outermost core, we developed software for calculating partial derivative in terms of perturbations of density and elastic constants in a liquid media and software for redetermining source parameters to utilize P-waves with short periods. We invert waveform records with shorter periods (up to 8 seconds) for the 3-D S-wave velocity structure of the mantle transition zone and the lowermost mantle, where the phases used to infer the outermost core sample. Thus, these developments will contribute to simultaneous inversion for the seismic velocity structure of the lowermost mantle and the uppermost outer core.

Academic Significance and Societal Importance of the Research Achievements

これまでよりも短い周期のS波を活用することによって、マントル遷移層および最下部マントルの地域的な3次元S波速度構造の最高解像度でのイメージングに成功した。その結果、マントル遷移層の沈み込みスラブの断裂を特定し、地質学的記録と対比することによって世界に先駆けて地球深部の年代決定を行った。また、既存の走時解析手法にとって不得手とされていた地球深部の低速度異常についても、低速度異常の内部構造のイメージングに成功した。本研究ではマントル遷移層および最下部マントルをこれまでにない解像度で地震波速度構造を推定することによって、地球内部ダイナミクスの理解に貢献をすることができた。

Research Products

• [Int'l Joint Research] マヒドン大学(タイ)
• [Int'l Joint Research] Academia Sinica(台湾)
• [Int'l Joint Research] マヒドン大学(タイ)
• [Int'l Joint Research] Academia Sinica (台湾)(その他の国・地域)
• [Journal Article] Seismic velocity structure of the upper inner core in the north polar region (2021)
  • Author(s): Ohtaki Toshiki、Tanaka Satoru、Kaneshima Satoshi、Siripunvaraporn Weerachai、Boonchaisuk Songkhun、Noisagool Sutthipong、Kawai Kenji、Kim Taewoon、Suzuki Yuki、Ishihara Yasushi、Miyakawa Koji、Takeuchi Nozomu
  • Journal Title: Physics of the Earth and Planetary Interiors Volume: 311 Pages: 106636-106636
  • DOI: 10.1016/j.pepi.2020.106636
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Effect of normal stress on the frictional behavior of brucite: application to slow earthquakes at the subduction plate interface in the mantle wedge (2021)
  • Author(s): Okuda Hanaya、Katayama Ikuo、Sakuma Hiroshi、Kawai Kenji
  • Journal Title: Solid Earth Volume: 12 Issue: 1 Pages: 171-186
  • DOI: 10.5194/se-12-171-2021
  • Peer Reviewed / Open Access
• [Journal Article] High-resolution 3-D S-velocity structure in the D″ region at the western margin of the Pacific LLSVP: Evidence for small-scale plumes and paleoslabs (2020)
  • Author(s): Suzuki, Y., K. Kawai, R. J. Geller, S. Tanaka, W. Siripunvaraporn, S. Boonchaisuk, S. Noisagool, Y. Ishihara, T. Kim,
  • Journal Title: Physics of the Earth and Planetary Interiors Volume: 307 Pages: 106544-106544
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] 3-D S-velocity structure of the mantle transition zone beneath Central America and the Gulf of Mexico inferred using waveform inversion (2019)
  • Author(s): Anselme F. E. Borgeaud, Kenji Kawai, Robert J. Geller
  • Journal Title: Journal of Geophysical Research: Solid Earth Volume: 124 Issue: 9 Pages: 9664-9681
  • DOI: 10.1029/2018jb016924
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] First‐principles Investigation of Frictional Characteristics of Brucite: An Application to Its Macroscopic Frictional Characteristics, Journal of Geophysical Research (2019)
  • Author(s): Hanaya Okuda , Kenji Kawai, Hiroshi Sakuma
  • Journal Title: Journal of Geophysical Research: Solid Earth Volume: 124 Issue: 10 Pages: 10423-10443
  • DOI: 10.1029/2019jb017740
  • Peer Reviewed
• [Journal Article] Thai Seismic Array (TSAR) Project (2019)
  • Author(s): Satoru Tanaka, Weerachai Siripunvaraporn, Songkhun Boonchaisuku, Noisagool Sutthipong, Taweoon Kim, Kenji Kawai, Yuki Suzuki, Yasushi Ishihara, Ryohei Iritani, Koji Miyakawa, Nozomu Takeuchi, Hitoshi Kawakatsu
  • Journal Title: Bulletin of the Earthquake Research Institute Volume: 94 Pages: 1-11
  • NAID: 120006902519
  • Int'l Joint Research
• [Journal Article] The Goshogake mud volcano field, Tohoku, northern Japan: An acidic, high-temperature system related to magmatic volcanism (2019)
  • Author(s): Komatsu, G., R. Ishimaru, N. Miyake, K. Kawai, M. Kobayashi, H. Sakuma, and T. Matsui
  • Journal Title: Geomorphology Volume: 329 Pages: 32-45
  • DOI: 10.1016/j.geomorph.2018.12.035
  • Peer Reviewed
• [Journal Article] Effects of redetermination of source time functions on the 3-D velocity structure inferred by waveform inversion (2018)
  • Author(s): Yamaya, L., A.F.E. Borgeaud, K. Kawai, R.J. Geller, K. Konishi
  • Journal Title: Physics of the Earth and Planetary Interiors Volume: 282 Pages: 117-143
  • Peer Reviewed
• [Journal Article] What is the origin of macroscopic friction? (2018)
  • Author(s): Sakuma, H., K. Kawai, I. Katayama, S. Suehara
  • Journal Title: Science Advances Volume: 4 Issue: 12 Pages: 1-6
  • DOI: 10.1126/sciadv.aav2268
  • Peer Reviewed / Open Access
• [Journal Article] High-pressure phase transitions of anorthosite crust in the Earth’s deep mantle (2017)
  • Author(s): Nishi M., Greaux S., Tateno S., Kuwayama Y., Kawai K., Irifune T., Maruyama S.
  • Journal Title: Geoscience Frontiers Volume: in press Issue: 6 Pages: 1-13
  • DOI: 10.1016/j.gsf.2017.10.002
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] Mantle flows in the lowermost mantle beneath the Northern Pacific inferred by 3-D waveform inversion for radially anisotropic structure (2020)
  • Author(s): 鈴木 裕輝, 河合 研志, ゲラー ロバート
  • Organizer: 日本地球惑星科学連合大会
  • Int'l Joint Research
• [Presentation] Imaging subducted slabs in the mantle through inversion of seismic waveforms (2020)
  • Author(s): 河合 研志, Borgeaud Anselme, 鈴木 裕輝, ゲラー ロバート
  • Organizer: 日本地球惑星科学連合大会
  • Int'l Joint Research / Invited
• [Presentation] Seismic structure near the inner core boundary in the north polar region (2020)
  • Author(s): 大滝 壽樹, 田中 聡, 金嶋 聰, Siripunvaraporn Weerachai, Boonchaisuk Songkhun, Noisagool Sutthipong, 河合 研志, Kim Taewoon, 鈴木 裕輝, 石原 靖, 宮川 幸治, 竹内 希, 川勝 均
  • Organizer: 日本地球惑星科学連合大会
  • Int'l Joint Research
• [Presentation] Interaction and Coevolution of the Core and Mantle in the Earth and Planets (2019)
  • Author(s): Kenji Kawai, Tsuyoshi Iizuka, Kenji Ohta, Taku Tsuchiya
  • Organizer: JpGU2019
• [Presentation] Waveform inversion for 3D anisotropic structure in D" beneath the Northern Pacific: Constraints on mineralogy and flow in the lowermost mantle (2019)
  • Author(s): Yuki Suzuki, Kenji Kawai, Robert J. Geller
  • Organizer: JpGU2019
• [Presentation] Detailed 3-D S-velocity structure within D" at the western Pacific LLSVP margin: smaller scale plumes and paleoslabs(Poster) (2019)
  • Author(s): Yuki Suzuki, Kenji Kawai, Robert J. Geller, Satoru Tanaka, Weerachai Siripuvaraporn, Songkhun Boonchaisuku, Noisagool Sutthipong, Yasushi Ishihara, Taweoon Kim, Koji Miyakawa, Nozomu Takeuchi
  • Organizer: JpGU2019
• [Presentation] Origin and role of lost continents (2019)
  • Author(s): Shigenori Maruyama, Kenji Kawai, Greaux Steeve, Dapeng Zhao
  • Organizer: JpGU2019
• [Presentation] 第一原理計算による層状鉱物gibbsiteの摩擦特性の研究(Poster) (2019)
  • Author(s): 奥田 花也, 河合 研志, 佐久間 博
  • Organizer: JpGU2019
• [Presentation] 3-D P- and S-velocity structure of the D″ layer beneath Central America and the Caribbean using waveform inversion (2019)
  • Author(s): Anselme F. E. Borgeaud, Kenji Kawai, Robert J. Geller
  • Organizer: JpGU2019
  • Invited
• [Presentation] Waveform inversion for the radial elastic and anelastic structure of the lowermost mantle beneath Central America and the Caribbean(Poster) (2019)
  • Author(s): Anselme F. E. Borgeaud, Frederic Deschamps, Kensuke Konishi, Kenji Kawai, Robert J. Geller
  • Organizer: JpGU2019
• [Presentation] Waveform inversion for the radial elastic and anelastic structure of the lowermost mantle beneath Central America and the Caribbean (2019)
  • Author(s): Anselme F. E. Borgeaud, Frederic Deschamps, Kensuke Konishi, Kenji Kawai, Robert J. Geller
  • Organizer: JpGU2019
• [Presentation] Imaging subducted slabs in the mantle from inversion of seismic waves (2019)
  • Author(s): Kenji Kawai
  • Organizer: International Workshop for Geophysical observation in Thailand Present and Future
  • Int'l Joint Research
• [Presentation] Imaging subducted slabs in the lowermost mantle from inversion of seismic waveforms (2019)
  • Author(s): Kenji Kawai, Anselme F.E. Borgeaud, Yuki Suzuki
  • Organizer: 2019年度 日本地球化学会年会
  • Invited
• [Presentation] Slip- and Velocity-Weakening Behaviors of Brucite Nanoparticle(Poster) (2019)
  • Author(s): H.Okuda, I.Katayama, H.Sakuma, K.Kawai
  • Organizer: The 7th International Conference on Coupled THMC Processes
  • Int'l Joint Research
• [Presentation] Seismic structure near the inner core boundary in the north polar region (2019)
  • Author(s): Toshiki Ohtaki, Satoru Tanaka, Satoshi Kaneshima, Weerachai Siripunvarporn, Songkhun Boonchaisuk, Sutthipong Noisagool, Kenji Kawai, Taewoon Kim, Yuki Suzuki, Yasushi Ishihara, Koji Miyakawa, Nozomu Takeuchi and Hitoshi Kawakatsu
  • Organizer: 2019 AGU Fall Meeting
  • Int'l Joint Research
• [Presentation] The Origin of Macroscopic Friction between Single Crystal Mica Surfaces (2019)
  • Author(s): Hiroshi Sakuma, Kenji Kawai, Ikuo Katayama, Shigeru Suehara
  • Organizer: Second International Symposium on Crustal Dynamics(ISCD-2)
  • Int'l Joint Research
• [Presentation] First-Principles Investigation for Frictional Characteristics of Brucite and its Application for Macroscopic Frictional Characteristics of Sheet-Structure Minerals (2019)
  • Author(s): Hanaya Okuda, Kenji Kawai, Hiroshi Sakuma, Ikuo Katayama
  • Organizer: Second International Symposium on Crustal Dynamics(ISCD-2)
  • Int'l Joint Research
• [Presentation] Sedimentary Records Of Ancient Mud Volcanism: How Do We Identify Mud Volcanoes In The Strattgraphy Of Mars? (2019)
  • Author(s): G. Komatsu, R. Ishimaru, K. Kawai, N. Miyake, M. Kobayashi, T. Matsui
  • Organizer: 50th Lunar and Planetary Science Conference in The Woodlands
  • Int'l Joint Research
• [Presentation] 波形インバージョンによる北部太平洋下D”領域の３次元S波速度構造推定 (2018)
  • Author(s): 鈴木裕輝, 河合研志, Robert J. Geller
  • Organizer: 日本地震学会秋季大会
• [Presentation] 震源時間関数の再決定が波形インバージョンによる３次元速度構造推定に与える影響の定量的評価 (2018)
  • Author(s): 山谷里奈, Anselme Borgeaud, 河合研志, Robert J. Geller, 小西健介
  • Organizer: 日本地震学会秋季大会
• [Presentation] 西太平洋直下最下部マントルにおける３次元S波速度構造から見るイザナギプレートとLLSVP (2018)
  • Author(s): 河合研志
  • Organizer: 新学術領域研究 核－マントルの相互作用と共進化～統合的地球深部科学の創成～A03-1地震・電磁気観測班の合同班会議