電磁探査法および地形・地質調査による新潟県十日町市泥火山の深部地下構造 Underground Structure of Mud Volcanoes in Tokamachi City, Niigata Prefecture Determined by Electromagnetic Exploration, and Geographical and Geological Surveys

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著者

    • 鈴木 浩一 SUZUKI Koichi
    • 電力中央研究所地球工学研究所地圏科学領域 Geosphere Science Sector, Civil Engineering Research Laboratory, Central Research Institute of Electric Power Industry

抄録

 In Tokamachi City, Niigata Prefecture, where Tertiary sedimentary rocks are distributed, excavation of the Mt. Nabetachiyama tunnel took a long time to complete due to the presence of a swelling mudstone zone. This swelling zone is distributed at a depth of 180m under the mud volcanoes. Geological and geographical surveys as well as electromagnetic surveys applying the Controlled Source Audio-frequency Magneto-Telluric Method (CSAMT), were carried out to clarify the geological structure under the mud volcanoes and the relationship between geographical features and the swelling zone. The laser scanner survey revealed that the geological structure around the topographic depression is intensely disturbed and the geological survey showed that the mud volcanoes and eruption points of groundwater and natural gas are located mainly along the outside edge of the geologically disturbed zone. This suggests that the area was active in the past due to the uplift and eruption of groundwater. The extremely low resistivity zone (ELR) at a depth of 400m with a diameter of 500m was detected below the geologically disturbed zone by the CSAMT survey. The ELR is estimated to correspond to a mud chamber filled with saline groundwater and mud, based on laboratory tests measuring the electrical properties of several rock samples obtained from the survey area. The low resistivity zone (LR) was also detected; it continues from the ELR to the mud volcano at the ground surface, indicating that saline groundwater, mud, and natural gas may be ascending via a concentric path to the mud volcanoes. On the basis of all the results obtained, it is interpreted that the swelling zone in the tunnel corresponds to the path of mobilized mud and saline groundwater in the fractured mudstone with abnormal pore water pressure.

収録刊行物

  • 地學雜誌

    地學雜誌 118(3), 373-389, 2009-07-07

    Tokyo Geographical Society

参考文献:  18件中 1-18件 を表示

被引用文献:  3件中 1-3件 を表示

各種コード

  • NII論文ID(NAID)
    10030365474
  • NII書誌ID(NCID)
    AN00322536
  • 本文言語コード
    JPN
  • 資料種別
    ART
  • ISSN
    0022135X
  • NDL 記事登録ID
    10386062
  • NDL 雑誌分類
    ZM41(科学技術--地球科学)
  • NDL 請求記号
    Z15-169
  • データ提供元
    CJP書誌  CJP引用  NDL  J-STAGE 
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