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Geochemical and limnological survey on crater lakes in Cameroon

Research Project

Project/Area Number 63041090
Research Category

Grant-in-Aid for Overseas Scientific Survey.

Allocation TypeSingle-year Grants
SectionField Research
Research InstitutionOkayama University

Principal Investigator

KUSAKABE Minoru  Institute for Study of the Earth's Interior, Okayama University, 地球内部研究センター, 教授 (20015770)

Co-Investigator(Kenkyū-buntansha) SHINOHARA Hiroshi  Department of Chemistry, Tokyo Institute of Technology, 理学部, 助手 (30196406)
NOJIRI Yukihiro  National Institute for Environmental Studies, 総理府技官 (10150161)
SATO Hiroaki  Faculty of Integrated Arts and Sciences, Hiroshima University, 総合科学部, 助教授 (60019495)
HIRABAYASHI Jun-ichi  Kusatsu-Shirane Volcano Observatory, Tokyo Institute of Technology, 草津白根火山観測所, 助教授 (30114888)
Project Period (FY) 1988 – 1989
Project Status Completed (Fiscal Year 1989)
Budget Amount *help
¥9,600,000 (Direct Cost: ¥9,600,000)
Fiscal Year 1989: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1988: ¥9,000,000 (Direct Cost: ¥9,000,000)
KeywordsLake Nyos / Cameroon / gas disaster / magmatic origin / bathymetry / flux of heat / CO_2 flux / disaster prevention
Research Abstract

Outburst of a large amount of CO_2 dissolved in Lake Nyos, Cameroon, killed more than 1700 people on 21 August 1986. The surveys made soon after the gas disaster indicate that the CO_2 is of magmatic origin and the lake is chemically stratified. We revisited the lake in December 1988. Our bottom sounding study revised the bathymetry by Hassert (1912). The conductivity-temperature-depth profiller (CTD) measurements and chemical analysis of the lake water revealed that temperature, total dissolved solids (TDS) and CO_2 content of water below 160 m increased considerably over the last 25 months. This supports the view that CO_2 is being supplied to the lake bottom in the form of warm, CO_2-charged, mineralized water. Fluxes of heat and CO_2 were estimated to be 0.36 MW and 515-560x10^6 mol/y, respectively. The CO_2 flux is consistent with that estimated from the He-T relationship. The CO_2 flux is large enough to saturate the lake's hypolimnion within 50 y. Using the CO_2-TDS-Si relationship and temperature dependence of amorphous silica solubility, chemical composition of the warm mineralized water was estimated. Existence of a CO_2-saturated fluid below the sedimentary cover is suggested. These are the important findings for disaster prevention.

Report

(1 results)
  • 1989 Final Research Report Summary
  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] M.Kusakabe,T.Ohsumi and S.Aramaki: "The Lake Nyos gas disaster:chemical and isotopic evidence in water and dissolved gases from three Cameroonian crater lakes,Nyos,Monoun and Wum." Journal of Volcanology and Geothermal Research. 39. 167-185 (1989)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Y.Sano,M.Kusakabe,J.Hirabayashi,Y.Nojiri,H.Shinohara,T.Njine and G.Tanyileke: "Helium and carbon fluxes in Lake Nyos,Cameroon:constraint on next lethal gas burst." Submitted to Earth and Planetary Science Letters. (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Y.Nojiri,M.Kusakabe,J.Hirabayashi,H.Sato,Y.Sano,H.Shinohara,T.Njine and G.Tanyileke: "Anestimate of CO_2 flux in Lake Nyos,Cameroon." Submitted to Nature. (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] H.Sato,M.Kusakabe,J.Hirabayashi,T.Njine,Y.Sano,Y.Nojiri,H.Shinohara and F.Tchoua: "A bottom sounding study of Lake Nyos and Lake Bambuluwe,NW Cameroon." Submitted to Bulletin of Volcanology. (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] H.Sato,F.Tchoua and M.Kusakabe: "Chemistry of olivine phenocryst in some Cameroonian basalts-implication to the primary magma compositions." To be submitted to Mineralogical Magazine. (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] M.Kusakabe and Y.Sano: "Origin of gases in Lake Nyos,Cameroon in“Natural Hazards in West and Central Africa"(S.J.Freeth,ed.)" Friedr.Viervey & Sons,Verlagsgeselschaft mbH,Braunschwerg Wiesbaden, (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] M. Kusakabe, T. Ohsumi and S. Aramaki: "The Lake Nyos gas disaster: chemical and isotopic evidence in waters and dissolved gases from three Cameroonian crater lakes, Nyos, Monoum and Wum" Journal of Volcanology and Geothermal Research. 39. 167-185 (1989)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Y. Sano, M. Kusakabe, J. Hirabayashi, Y. Nojiri, H. Shinohara, T. Njine and G. Tanyileke: "Helium and carbon fluxes in Lake Nyos, Cameroon: constraint on next lethal gas burst" Submitted to Earth and Planetary Science Letters. (1990)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Y. Nojiri, M. Kusakabe, J. Hirabayashi, H. Sato, Y. Sano, H. Shinohara, T. Njine and G. Tanyileke: "An estimate of CO_2 flux in Lake Nyos, Cameroon" Submitted to Nature. (1990)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] H. Sato, M. Kusakabe, J. Hirabayashi, T. Njine, Y. Sano, Y. Nojiri, H. Shinohara and F. Tchoua: "A bottom sounding study of Lake Nyos and Lake Bambuluwe, NW Cameroon" Submitted to Bulletin of Volcanology. (1990)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] H. Sato, F. Tchoua and M. Kusakabe: "To be submitted to Mineralogical Magazine" Chemistry of olivine phenocryst in some Cameroonian basalts - implication to the primary magma compositions. (1990)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] M. Kusakabe and Y. Sano: Origin of gases in Lake Nyos, Cameroon, in "Natural Hazards in West and Central Africa" (S.J. Freeth et al., ed.). Friedr. Viervey & Sns, Verlagsgeselschaft mbH, Braunschwerg Wiesbaden, (1990)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary

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Published: 1988-04-01   Modified: 2016-04-21  

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