2006 Fiscal Year Final Research Report Summary
Study of the thermal structure of the seismogenic zone along the Nankai margin through heat flow measurements in shallow sea areas
| Project/Area Number |
16340126
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Solid earth and planetary physics
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| Research Institution | The University of Tokyo |
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Principal Investigator |
YAMANO Makoto The University of Tokyo, Earthquake Research Institute, Associate professor (60191368)
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| Co-Investigator(Kenkyū-buntansha) |
HIBIYA Toshiyuki The University of Tokyo, School of science, Professor (80192714)
ASHI Juichiro The University of Tokyo, Graduate School of Frontier Sciences, Associate professor (40251409)
KINOSHITA Masataka Japan Agency for Marine Earth Science and Technology, Institute for Research on Earth Revolution, Group leader (50225009)
MATSUBAYASHI Osamu National Institute of Advanced Industrial Science and Technology, Geological Survey of Japan, Leader (70358034)
GOTO Shusaku National Institute of Advanced Industrial Science and Technology, Geological Survey of Japan, Research scientist (10378557)
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| Project Period (FY) |
2004 – 2006
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| Keywords | terrestrial heat flow / long-term temperature monitoring / subduction zone / Nankai Trough / seismogenic zone / bottom water temperature / subsurface temperature structure / Kuroshio |
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| Research Abstract |
1. We conducted long-term monitoring of temperature profiles in sediments and bottom water temperature using pop-up type instruments. Continuous records for 5 to 17 months were obtained at 17 stations along the Nankai margin.
2. Reducing the effect of bottom water temperature variation from the sediment temperature records, we could obtain heat flow values at six stations with relatively shallow water depths. We also showed that it is possible to determine heat flow in shallow sea by analyzing sediment temperature profiles measured with ordinary deep-sea probes in combination with long-term bottom water temperature records. This new method was applied to the data at three stations and heat flow was successfully determined.
3. We evaluated the minimum water depth at which heat flow can be measured with ordinary probes and the length of monitoring time with pop-up type instruments necessary for heat flow determination based on long-term bottom water temperature records. Variations in bottom water temperature were also compared with physical oceanography data. The periodicity in the temperature variations might be related to meandering of the surface current (Kuroshio).
4. Heat flow measurements were also made in deep sea areas using ordinary probes. Combining the obtained data with the results in shallow sea areas mentioned above and the existing data, we could construct a heat flow profile across the Nankai Trough in the area southeast of the Ki-i peninsula (off-Kumano).
5. The temperature structure of the Nankai subduction zone was calculated in the off-Kumano area and in the areas off eastern Shikoku, taking account of effects of sedimentation on the incoming oceanic plate and fluid and sediment flows in the accretionary prism. We estimated the frictional heating (shear stress) along the plate boundary by comparing the calculated surface heat flow with the observed data.
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Research Products
(12 results)
