1995 Fiscal Year Final Research Report Summary
Study on Geothermal Fluid Flow Processes and Subsurface Structure
| Project/Area Number |
05452078
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
YUSA Yuki Kyoto University, Faculty of Science, Professor, 理学部, 教授 (90025403)
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| Co-Investigator(Kenkyū-buntansha) |
OHSAWA Shinji Kyoto University, Faculty of Science, Res.Asso., 理学部, 助手 (30243009)
SUDO Yasuaki Kyoto University, Faculty of Science, Asso.Prof., 理学部, 助教授 (40025466)
FUKUDA Yoichi Kyoto University, Faculty of Science, Asso.Prof., 理学部, 助教授 (30133854)
TAKEMURA Keiji Kyoto University, Faculty of Science, Asso.Prof., 大学院理学研究科, 助教授 (00201608)
KITAOKA Koichi Kyoto University, Faculty of Science, Asso.Prof., 理学部, 助教授 (30093230)
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| Project Period (FY) |
1993 – 1995
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| Keywords | Geothermal Activity / Geothermal Fluid / Subsurface Resistivity / Stable Isotope Ratio / Two-phase Flow / Composition of Geothermal Gas / Gravity / Graben |
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| Research Abstract |
(1) Flow path of geothermal water : Based on data of drillings and the distribution of chemical compositions of geothermal waters, a method to analyze the subsurface flow path of geothemal waters was studied, and flow paths of several kinds of geothermal waters were detected in the Beppu geothermal field. The westward flow to Yufuin from Beppu was also suggested.
(2) Origin of geothermal water : The stable isotope studies have revealed that all geothermal waters in the Beppu area are originated from meteoric waters, while geothermal waters in the Kuju area contain magmatic fluids.
(3) Characteristics of geothermal gas : It was clarified that the composition of geothermal gases in the Central Kyushu was different from those in Northeast Japan and in the Southern Kyushu. This study also suggested a possibility of uprising of deep fluids in the Central Kyushu.
(4) Geothermal structure : Based on processes of heat discharge at the ground surface and the subsurface resistivity, a modelling method of geothermal structure was studied using a theory of two-phase flow of geothermal fluids ; by which a geothermal model to about 6 km deep of the Beppu geothermal system has been constructed.
(5) Subsurface structure : Analyzing gravity data, it was shown that the Beppu area consisted of several basins and grabens which were formed at the north side of the Median Tectonic Line. It was also indicated that there were the region of seismic wave attenuating, low density and brittle materials beneath the Kuju volcanic and geothermal area.
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