| Project/Area Number |
04041055
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Field Research |
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| Research Institution | Nagoya University |
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Principal Investigator |
YAMADA Isao (1993-1994) Nagoya University, 理学部, 助教授 (60022670)
深尾 良夫 (1992) 名古屋大学, 理学部, 教授 (10022708)
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| Co-Investigator(Kenkyū-buntansha) |
FUKAO Yoshio Tokyo University, 地震研究所, 教授 (10022708)
HAMADA Nobuo Japan Meteorological Agency, 気象研究所, 室長
TAKANO Kiyoshi Tokyo University, 地震研究所, 講師 (80134659)
KASAHARA Junzo Tokyo University, 地震研究所, 助教授 (70012953)
SUDA Naoki Nagoya University, 理学部, 助手 (10222069)
WALKER D.A. ハワイ大学, 地球物理研究所, 教授
浜田 信夫 気象庁, 気象研究所, 室長
山田 功夫 名古屋大学, 理学部, 助教授 (60022670)
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| Project Period (FY) |
1992 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥13,500,000 (Direct Cost: ¥13,500,000)
Fiscal Year 1994: ¥4,500,000 (Direct Cost: ¥4,500,000)
Fiscal Year 1993: ¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 1992: ¥5,000,000 (Direct Cost: ¥5,000,000)
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| Keywords | Mariana Basin / Ontong Java Plateau / Oldest seafloor / Rayleigh wave / レーリー波 / 群速度 / PATS / ポンペイ / 広帯域地震計 / 表面波 / S波構造 / 地震観測 / 地震計 / 海洋底 / ポセイドン計画 / ポンペイ島 / 南鳥島 / 西太平洋 / 地球深部 |
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| Research Abstract |
In March 1993, a new station PATS was established on Pacific island, Micronesia, for which we developed a new recording system in a continuous mode. We measured Rayleigh wave group velocities in a period rang 20-150s for the path from Mariana to PATS which is purely the Mariana Basin, and for the path from Solomon island which is purely the Ontong Java Plateau. The Mariana Basin is the oldest seafloor of the Pacific (>16ma) and the Ontong Java Plateau is lava plateau on the seafloor. We got a faster dispersion curve of Rayleigh wave on the Mariana Basin and a lower one on the Ontong Java Plateau. The dispersion curves for the two paths are in marked contrast on the basis of which the shear velocity models were constructed.
The Mariana Basin has an at least 120km thick plate with a velocity faster than the standard oceanic model which is the oldest seafloor (160-170ma) in the pacific. Relations between the seafloor age and the surface wave velocity in the Pacific have been studied by Mitchell and Yu (1980), Yoshii (1975). However their studies lack the result for the oldest seafloor because of the poor path coverage over the Mariana Basin. The Ontong Java Plateau has thick crust more than 40km and has thick plate more than 80km.
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