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Real form of the cap structure of volcanic hydrothermal system and estimate of permeability

Research Project

Project/Area Number 18K03777
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 17040:Solid earth sciences-related
Research InstitutionTokyo Institute of Technology

Principal Investigator

Kanda Wataru  東京工業大学, 理学院, 准教授 (00301755)

Co-Investigator(Kenkyū-buntansha) 高倉 伸一  国立研究開発法人産業技術総合研究所, 地質調査総合センター, 上級主任研究員 (50357349)
丹保 俊哉  公益財団法人立山カルデラ砂防博物館, 学芸課, 学芸課長補佐 (10574311)
Project Period (FY) 2018-04-01 – 2022-03-31
Project Status Completed (Fiscal Year 2021)
Budget Amount *help
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2020: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2019: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2018: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
Keywords比抵抗構造 / 透水係数 / 浸透率 / 水蒸気噴火 / 変質鉱物 / 比抵抗 / 流動カラム実験 / キャップ構造 / 火山熱水系 / 浸透実験
Outline of Final Research Achievements

To clarify the subsurface structure of the volcanic hydrothermal system in a highly acidic environment, we constructed a flow experiment column device and tried to measure the electrical resistivity and the hydraulic conductivity simultaneously, but we could not obtain sufficient measurement results.
In Tateyama Jigokudani, where the detailed resistivity structure was estimated, the distribution of soil diffuse CO2 flux and the hydraulic conductivity of the soil were measured, and the chemical analysis of the soil was performed. As a result, although the surface layer in the central part of Jigokudani is not as low in permeability as the clay layer in the peripheral part, we found that the hydraulic conductivity is reduced by silica minerals and sulfate minerals. Although the direct relationship between resistivity and permeability was not obtained, it is concluded that the low resistivity of the surface layer is caused by highly acidic fluids containing a large amount of ions.

Academic Significance and Societal Importance of the Research Achievements

水蒸気噴火の発生場と考えられている火山熱水系キャップ構造は、低浸透率かつ低比抵抗のキャップロックとその下部の流体溜りから形成されていると考えられているが、強酸性環境下にある火口や噴気地帯直下では、その実体は必ずしも明らかではなかった。本研究により、透水性を低下させている物質はシリカ鉱物や硫黄および硫酸塩鉱物であり、低比抵抗を担っている物質は強酸性の熱水であることが確認できた。従来の低比抵抗かつ低浸透率の粘土によるキャップが形成されているとする比抵抗構造の解釈を覆すものであり、水蒸気噴火発生場の理解が進展するものと期待できる。

Report

(5 results)
  • 2021 Annual Research Report   Final Research Report ( PDF )
  • 2020 Research-status Report
  • 2019 Research-status Report
  • 2018 Research-status Report
  • Research Products

    (3 results)

All 2021 2020 2019

All Journal Article (1 results) (of which Peer Reviewed: 1 results,  Open Access: 1 results) Presentation (2 results) (of which Int'l Joint Research: 1 results,  Invited: 1 results)

  • [Journal Article] Hydrothermal system of the active crater of Aso volcano (Japan) inferred from a three-dimensional resistivity structure model2019

    • Author(s)
      Kanda Wataru、Utsugi Mitsuru、Takakura Shinichi、Inoue Hiroyuki
    • Journal Title

      Earth, Planets and Space

      Volume: 71 Issue: 1

    • DOI

      10.1186/s40623-019-1017-7

    • Related Report
      2018 Research-status Report
    • Peer Reviewed / Open Access
  • [Presentation] 立山地獄谷における土壌ガス・浸透率測定2021

    • Author(s)
      神田 径・丹保俊哉
    • Organizer
      日本火山学会2021年度秋季大会
    • Related Report
      2021 Annual Research Report
  • [Presentation] Resistivity structure of preparation zone for phreatic eruptions in several volcanoes in Japan2020

    • Author(s)
      Kanda Wataru, Seki Kaori, Matsunaga Yasuo
    • Organizer
      Workshop on the mechanism of Phreatic Eruption
    • Related Report
      2019 Research-status Report
    • Int'l Joint Research / Invited

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Published: 2018-04-23   Modified: 2023-01-30  

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