| Summary: | application/pdf Regionalization of the North American Continent, the Arctic Ocean Basin and their surroundings with regard to the group velocity dispersion character of Rayleigh waves (period 20-40 seconds) were made by means of ""crossing-path technique."" In the North American Continent, dispersion index in the Canadian shield was found to be as low as 5.5. This result was discussed by comparing with the dispersion data obtained by J. N. Brune etal. It was suggested that Hudson Bay has a thick sediment. In the Arctic Ocean, special dispersion character was not observed along the narrow seismic belt which is considered to be the extension of the Mid-Atlantic Ridge. A dispersion region with extremely high dispersion index of 10 was again confirmed around Novaya Zemlya. The peculiar dispersion character of Rayleigh waves was discovered along the path covering Greenland.|これまでと同じ方法で,北米大陸と北極海をいくつかの分散区に分けてみた.北米大陸では,予想通り,カナダ楯状地が分散指数5.5という,大陸としては大変に小さな値をもつ地区であることが明かになった(第4図).唯,J. Bruneらが,カナダ楯状地を代表する地殻マントルモデルとしてきめたCANSDモデルを見出ナのに用いた分散資料を,こんど得た分散区の分布で検討してみると,分散指数9を示すハドソン湾まで含んだ経路の資料も入っているので,CANSDは,カナグ楯状地だけのモデルとしては適当とは思えない. departmental bulletin paper
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