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Study of accuracy of synthetic waveforms and earthquake occurrence site in and around the source area of the 2011 Tohoku-oki earthquake by using a land-ocean unified 3D structure model

Research Project

Project/Area Number 16K05535
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Research Field Solid earth and planetary physics
Research InstitutionTokyo Institute of Technology

Principal Investigator

Okamoto Taro  東京工業大学, 理学院, 助教 (40270920)

Co-Investigator(Kenkyū-buntansha) 竹中 博士  岡山大学, 自然科学研究科, 教授 (30253397)
Project Period (FY) 2016-04-01 – 2020-03-31
Project Status Completed (Fiscal Year 2019)
Budget Amount *help
¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2017: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2016: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Keywords差分法 / GPU / 東北地方太平洋沖地震 / 地震波トモグラフィー / FDM / 地震波計算 / 地球内部構造 / 断層破壊過程 / GPU計算 / 大規模計算
Outline of Final Research Achievements

We evaluate the accuracy of synthetic waveforms for small earthquakes in the source area of the 2011 Tohoku-Oki earthquake (MJMA 9.0) at the Japan Trench. We compute the synthetic waveforms on the basis of a land-ocean unified 3D structure model using our HOT-FDM. In estimating the source parameters, we apply FAMT method that we have recently proposed. We find that the FAMT solutions for events with shallow-angle thrusting mechanisms are located near the plate interface, which demonstrates the importance of using a 3D model. We find that the full waveforms with periods shorter than about 10 s are not well reproduced. At periods around 4 s, the initial body waveforms can be modeled, but the later surface waves are difficult to reproduce correctly. We further examine the 3D sensitivity kernels: for short-period wavefield (below around 10 s) we observe a curved pattern which cannot be predicted by 1D earth models. This indicates the effects of 3D heterogeneity.

Academic Significance and Societal Importance of the Research Achievements

地震が発生した場所やメカニズムを推定するには地震波波形データが重要なデータとなる。一方で日本周辺の沈み込み帯は内部構造が複雑であるため地震波伝播にも大きな影響がある。これは地震解析の精度にも影響を及ぼすため、本研究では計算した地震波波形の精度を詳しく検討した。さらに地震波が構造モデルのどの部分に強く影響されているかを検討し、3次元構造モデルの効果などの構造モデルを改良する上での知見を得た。

Report

(5 results)
  • 2019 Annual Research Report   Final Research Report ( PDF )
  • 2018 Research-status Report
  • 2017 Research-status Report
  • 2016 Research-status Report
  • Research Products

    (6 results)

All 2019 2018 2017 2016

All Journal Article (1 results) (of which Peer Reviewed: 1 results,  Open Access: 1 results) Presentation (5 results) (of which Int'l Joint Research: 1 results)

  • [Journal Article] Evaluation of accuracy of synthetic waveforms for subduction-zone earthquakes by using a land-ocean unified 3D structure model2018

    • Author(s)
      Taro Okamoto, Hiroshi Takenaka and Takeshi Nakamura
    • Journal Title

      Earth, Planets and Space

      Volume: 70 Issue: 1 Pages: 1-10

    • DOI

      10.1186/s40623-018-0871-z

    • Related Report
      2018 Research-status Report
    • Peer Reviewed / Open Access
  • [Presentation] 東北沖の陸海統合3次元構造モデルに基づく波形トモグラフィーの試み2019

    • Author(s)
      岡元 太郎、竹中 博士、中村 武史
    • Organizer
      日本地震学会2019年度秋季大会
    • Related Report
      2019 Annual Research Report
  • [Presentation] 東北沖の陸海統合3次元構造モデルに基づくアジョイントカーネルの計算と波形インバージョンによる構造モデル改良の考察2018

    • Author(s)
      岡元 太郎, 竹中 博士, 中村 武史
    • Organizer
      日本地球惑星科学連合2018年大会
    • Related Report
      2018 Research-status Report
  • [Presentation] Waveform Tomography by Using The Adjoint Kernels Based on a Land-Ocean Unified 3D Structure Model For The Tohoku-Oki area of The Japan Trench, Japan2018

    • Author(s)
      Taro Okamoto, Hiroshi Takenaka, Takeshi Nakamura
    • Organizer
      American Geophysical Union, 2018 Fall Meeting
    • Related Report
      2018 Research-status Report
    • Int'l Joint Research
  • [Presentation] 陸海統合3次元構造モデルにもとづく日本海溝の浅い地震のFAMT解析2017

    • Author(s)
      岡元太郎・竹中博士・中村武史
    • Organizer
      日本地震学会2017年秋季大会
    • Related Report
      2017 Research-status Report
  • [Presentation] 大規模シミュレーションとアジョイントカーネルに基づく沈み込み帯での地震波伝播の考察2016

    • Author(s)
      岡元太郎・竹中博士・中村武史・青木尊之
    • Organizer
      日本地球惑星科学連合2016年大会
    • Place of Presentation
      幕張メッセ国際会議場(千葉市)
    • Related Report
      2016 Research-status Report

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Published: 2016-04-21   Modified: 2021-02-19  

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