The models investigated here consist of a superficial or a sandwiched high-velocity layer and a lower-velocity half space medium. The idea of the so-called leaking mode plays an important role in understanding the dispersive character of these models. Approximate dispersion curves of leaking modes have been calculated for various high-velocity layer models by the present author. The results are somewhat unusual; for example, a part of the phase velocity curves for these models often shows an inverse dispersion. This feature suggests a strong resemblance to the M21 wave in a simple ""plate"" model. Model experiments were done to examine the reliability of the approximate dispersion curves. The agreement of the observed data with those curves is satisfactory. Complex roots of the period equations are also calculated for the same models. Phase velocity curves derived from real parts of them agree well with the approximate ones. Imaginary parts of the complex roots give the attenuation of the leaking modes. Attenuation coefficients observed in a model experiment were well explained by the imaginary part. The idea of the leaking mode seems to be the most easy and beautiful approach to understanding the dispersive feature of the highvelocity layer models.|表層又は中間層が半無限媒質より速いP波,S波速度を有するようなモデル(以下高速度層モデルと略称する.)を伝わる表面波の性質は,大変興味ぶかい問題である.本論文ではこの種の表面波の性質のうち,主として分散について述べる.
雑誌名
東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo
巻
48
号
5
ページ
691 - 706
発行年
1970-12-05
ISSN
00408972
書誌レコードID
AN00162258
フォーマット
application/pdf
日本十進分類法
453
出版者
東京大学地震研究所
出版者別名
Earthquake Research Institute, University of Tokyo
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37. Dispersion of Surface Waves in High-Velocity Layer Models
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