第91回ジオダイナミクスセミナー
　　　Geodynamics　Seminar

　　　　　　「大西洋地域の表面波トモグラフィー」
　　　"Surface-wave tomography of the Atlantic region"

　　　　　　　講師：松原邦明（愛媛大学修士１年）

　　 　　　　　 　　　　　
　　　　　主催　：　愛媛大学地球深部ダイナミクス研究センター
　　　　　日時　：　２００４年２月２０日（金）　午後17時〜
　　　　　場所　：　愛媛大学理学部講義棟　２０１教室

要　旨
　The two-dimensional group velocity distribution beneath the Atlantic Ocean is determined by inverting the fundamental-mode data of Rayleigh waves in order to better constrain the structure and dynamics of the region. The previous regional tomographic studies are carried out by using surface waves passing through both the oceanic and continental region to increase the path coverage. The velocity perturbations are represented with respect to the average velocity or global standard model (e.g., PREM). Velocities in continental regions can shift the average velocity level, and so it is possible that small anomalies in oceanic regions become invisible. In this study, we selected only the ray paths passing through the Atlantic Ocean to delineate images of the oceanic area without the influence of anomalies in the continental region. The results show that the ridge axis and ocean basins exhibit high velocity at periods from 18 s to 30 s, reflecting the surface topography and isostasy, respectively. The ridge axis shows low velocity at periods longer than 50 s and become stronger at longer periods. There are good correlations between some hotspots and low velocity anomalies.




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　　　 　　　　　　　　　　　　　　　　E-mail　　yamazaki@sci.ehime-u.ac.jp