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Investigations of volcanic structure and intruded magma by means of the geoelectrical method - Usu, Miyake-jima and Hokkaidou Komagatake -

Research Project

Project/Area Number 09440155
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field 固体地球物理学
Research InstitutionHOKKAIDO UNIVERSITY

Principal Investigator

NISHIDA Yasunori  Grad. School of Sci., Hokkaido Univ., Pro., 大学院・理学研究科, 教授 (60000874)

Co-Investigator(Kenkyū-buntansha) KAGIYAMA Tsuneomi  Earthq. Res. Inst., Univ. Tokyo, Asso. Pro., 地震研究所, 助教授 (50126025)
TANAKA Yoshikazu  Grad School of Sci., Kyoto Univ., Asso. Pro., 理学研究科, 教授 (00025420)
SASAI Yoichi  Earthq. Res. Inst., Univ. Tokyo, Asso. Pro., 地震研究所, 助教授 (20012924)
OGAWA Yasuo  Geol. Surv. Jpn., Geophysisist., 地震調査所, 主任研究官 (10334525)
HASHIMOTO Takeshi  Grad School of Sci., Kyoto Univ., Inst., 理学研究科, 助手 (70283588)
松波 武雄  北海道立地下資源調査所, 地域エネルギー科, 科長(研究職)
Project Period (FY) 1997 – 1999
Project Status Completed (Fiscal Year 1999)
Budget Amount *help
¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 1999: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1998: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1997: ¥3,700,000 (Direct Cost: ¥3,700,000)
KeywordsMagma prospecting / Magnetotellurics / Resistivity structure / Self-potential / Hydrothermal circulation / Usu volcano / Miyake-jima volcano / Hokkaido-komagatake / 比抵抗構造 / 流動電位 / 北海道駒ヶ岳 / 火山 / マグマ / 地下水環境 / マグネトテルリック法
Research Abstract

Present study has aimed to elucidate the volcano-hydrological environment including the hydrothermal circulation system and to detect the intruded magma by using the geoelectrical methods. For these purposes, we made magnetotelluric observations and self-potential measurements on Usu (dacite magmatism). Miyake-jima (basaltic magmatism) and Hokkaido Komagatake (andesitic magmatism) volcanoes.
1) The common feature of the resistivity structure is seen beneath the three volcanic edifices: The first layer (100m or so) is resistive (about 1000 ohm-m) due to the volcanic rocks and sediments. The second layer is composed of the conductive rocks (several to several tens of ohm-m), suggesting the existence of the ionized water. This layer covers the relatively resistive third layer (several hundreds of ohm-m). The third layer is assumed to be the pre-Tertiary rocks.
2) Positive self-potential anomalies are commonly observed on summit craters (Usu, 400 mV; Miyake-jima, 800 mV; Hokkaido Komagatake, 600 mV). These anomalies can originate from the upwelling of hot groundwater warmed by the heat supplied from deep-seated magma. These findings of hydrothermal circulation are important to consider the magma cooling process.
3) Magnetotelluric soundings on Usu revealed the relatively highly resistive body (400 ohm-m or so) beneath the summit crater. Considering the relation between the resistivity of dacite rock and temperature, and the fumarolic temperature of Usu (500〜600℃, this body is identified as the intruded magma at the time of the 1977-1978 eruptions.

Report

(4 results)
  • 1999 Annual Research Report   Final Research Report Summary
  • 1998 Annual Research Report
  • 1997 Annual Research Report
  • Research Products

    (13 results)

All Other

All Publications (13 results)

  • [Publications] 西田泰典: "有珠火山の構造"マグマ探査―現状と展望―論文集(京都大学防災研究所編). 73-82 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] Sasai Y.: "Electromagnetic monitoring of Miyake-jima Volcano, Izu-Bonin arc, Japan : A preliminary report"Jour.Geomag.Geoelectr.. 49.11/12. 1293-1316 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] 谷元健剛: "北海道駒ケ岳におけるMTおよびSP観測(序報)-1998年10月25日小噴火に前後して-"Conductivity Anomaly 1999年研究会論文集. 57-64 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] 谷元健剛: "北海道駒ケ岳における火山電磁気学的研究(第2報)-自然電位連続観測-"Conductivity Anomaly 2000年研究会論文集. (印刷中). (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] Nishida, Y and H. Oshima: "Structure of Usu Volcano."Proc. Symp. On Magma Prospecting -Present condition and reviews (ed. By Kyoko Univ.). 73-82 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] Sasai, Y., J. Zlotnicki, Y. Nishida, et al.: "Electromagnetic monitoring of Miyake-jima Volcano, Izu-Bonin arc, Japan : A preliminary report."Jour. Geomag. Geoelectr.. 49, 11/12. 1293-1316 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] Tanimoto, K., Y. Nishida, et al.: "Mt and SP observations on Hokkaido Komagatake Volcano (1) -Before and after the small phreatic eruption occurred on Oct. 25, 1998-."Proc. Conductivity Anomaly Symp.(1999). 57-64 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] Tanimoto, K., Y. Nishida, et al.: "Volcano-electromagnetic study on Hokkaido Komagatake Volcano (2) -Continuous measurement of the self-potential field-."Proc. Conductivity Anomaly Symp.(2000). (in press). (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] 谷元健剛: "北海道駒ヶ岳における火山電磁気学的研究(第2報)―自然電位連続観測―"Conductivity Anomaly 研究会論文集. (印刷中). (2000)

    • Related Report
      1999 Annual Research Report
  • [Publications] 西田泰典: "有珠火山の構造" マグマ探査-現状と展望-論文集(京大防災研). 73-82 (1997)

    • Related Report
      1998 Annual Research Report
  • [Publications] Sasai, Y.: "Electromagnetic monitoring of Miyake-jima Volcano, Izu-Bonin arc, Japan: A preliminary report." J.Geomag.Geoelectr.,. 49. 1293-1316 (1997)

    • Related Report
      1998 Annual Research Report
  • [Publications] 西田泰典: "有珠火山の構造" マグマ探査-現状と展望- 論文集(京大防災研). 73-82 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] Sasai,Y.: "Electromagnetic monitoring of Miyake-jima Volcano,Izu-Boninarc,Japan." J.Geomag.Geoelectr.49・11/12. 1293-1316 (1997)

    • Related Report
      1997 Annual Research Report

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Published: 1997-04-01   Modified: 2023-01-05  

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