2020 Fiscal Year Final Research Report

Application of ground penetrating radar survey to visualization of 3-dimensional near-surface structure of strike-slip active faults

Research Project

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Project/Area Number	18K03768
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Review Section	Basic Section 17030:Human geosciences-related
Research Institution	Central Research Institute of Electric Power Industry
Principal Investigator	Kimura Haruo 一般財団法人電力中央研究所, 地球工学研究所, 主任研究員 (00723652)
Co-Investigator(Kenkyū-buntansha)	堤浩之同志社大学, 理工学部, 教授 (60284428) 中西利典ふじのくに地球環境史ミュージアム, 学芸課, 准教授 (10462582)
Project Period (FY)	2018-04-01 – 2021-03-31
Keywords	活断層 / アクティブテクトニクス / 物理探査 / 極浅部地下構造 / 地中レーダ / 北伊豆断層帯 / 布田川断層帯 / 中央構造線活断層系
Outline of Final Research Achievements	We conducted ground penetrating radar surveys to reveal the 3-dimensional near-surface structure at Tashiro site on the Tanna fault in the Kita-Izu fault zone, Dozon site on the Futagawa fault in the Futagawa fault zone, and Yamaguchi site on the Ikeda fault in the Median Tectonic Line active fault system. The distribution of buried channels showing strike-slip displacement caused by the active faults was obtained at each site. We also compared the results with the results of 2-dimensional ground penetrating radar profiling at other survey sites, and we discussed the effectiveness of the ground penetrating radar survey for visualizing the 3-dimensional near-surface structure of strike-slip active faults. As a result, it was found that this method can be applied to the detection of strike-slip deformation exceeding about 1 m, although there are some conditions such as the limitation of the resolution and the influence of geology and artifacts near the survey site.
Free Research Field	構造地質学，物理探査学
Academic Significance and Societal Importance of the Research Achievements	活断層調査では断層変位の検出は基本的な調査項目となる．とくに横ずれ変位の詳細な解明のためには三次元トレンチ掘削調査が有効である．しかし，土地利用が集約的で都市化の進んだ我が国では，三次元トレンチに要する広い用地の確保には困難が伴い，掘削調査を補完できる効果的な地下探査法の確立が望まれている．本研究では，地中レーダ探査を横ずれ断層直下の地下構造探査に適用した．その結果，横ずれ変形を受けた埋没地形の分布を可視化し，横ずれ変位量の検出に成功した．一方，分解能や探査地点の地質・ノイズ状況等の制約も存在した．今後，こうした制約を踏まえた上での手法の利活用と，制約を克服するための手法の高度化が望まれる．