| Project/Area Number |
04402011
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体地球物理学
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| Research Institution | Chiba niversity |
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Principal Investigator |
ASANUMA Toshio (1993) Chiba Univ., Dep.Earth Sci.Lecturer., 理学部, 講師 (50092028)
平田 直 (1992) 千葉大学, 理学部, 助教授 (90156670)
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| Co-Investigator(Kenkyū-buntansha) |
HIRATA Naoshi Tokyo Univ., Earthq4a2e Res. Inst.Assoc.Prof., 地震研究所, 助教授 (90156670)
ITO Tanio Chiba Univ., Dep.Earth Sci.Professor, 理学部, 教授 (50111448)
ISEZAKI Nobuhiro Chiba Univ., Dep.Earth Sci.Professor, 理学部, 教授 (60107943)
浅沼 俊夫 千葉大学, 理学部, 助手 (50092028)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥25,000,000 (Direct Cost: ¥25,000,000)
Fiscal Year 1993: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1992: ¥24,100,000 (Direct Cost: ¥24,100,000)
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| Keywords | Tsushma Basin / Yamato Basin / Kita-oki Bank / crustal structure / Ocean bottom seismometer / Yamato Bank / ocean bottom electro-magnetometer / three copnent magnetometer / 北隠岐碓 / 海底磁力計 / 大和碓 / 制御地震 |
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| Research Abstract |
We studied structure and evolution of the Lithosphere in the ocean-continent boundary zne in the southwestern part of the Japa Sea. We conducted a geohysical experiment in the Tsushima basin including seismic and geomagnetic measurements in 1992. An analysis f the data revealed the crusta and uppermost mantle structure in the Tsushima and Yamato basins and the northern part of the Kita-oki bank. Te Tsushima basin has a similar crust t that in the Yamato basin : both basins have a 14-km-thick crust, which is twice as thick as an average oceanic crust. On the contrary, the transition zone from the Ts4sh50a bas5n t6 the Ya0at6 bas5n, where 5s a sha336w water between the Yamato banks, has a 24-km thick crust. The veocity distribution in the crust indicates a continental characteristic including a 6-km/s layr. Electromagnetic observation using three ocean bottom electro-magnetometers resulted in that the specific electric resistance beneath the Tsushima Basin is less than that beneath the Japanese Islands and the Koren Penisula mainly due t presence of a lot o free water in the crust and that there needs no conducte in the upper mantle shallower than 160km taking the first dimensional mdelling into account.
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