1. Effects of Intervenient Boundaries on the Elastic Wave Propagation

Propagation of waves through various kinds of intervenient boundaries is systematically investigated in some simple models, namely the first and second order discontinuities and the perfectly continuous medium. The moduli of transmitted and reflected waves vary between maxima and minima with certain frequency intervals for the first order discontinuity and tend from one value to another for the second order discontinuity with increasing frequency. For the perfectly continuous medium, those vary monotoni- cally. It is necessary to observe the wide band spectrum of the reflected waves to discuss the nature of the boundary. The apparent phase velocity is determined from the phase of the complex transmission coefficient. It is faster in long period waves than in short ones.地震波は一種の進行波であり,それを伝える場はたとえ等方と考えられるにしても不均質である.不均質媒質における波の表現から進行波だけを分離することはできないので,進行波の安定性を談論するためには，不均質媒質を挟んで両側に均質媒質を置いて,それらの中の特定方向に伝わる波を調べるという手段をとらなくてはならない.（このことについて,速度が一様に変化している場合について一つの証明を与えた.)今回はこのような立場から,簡単な問題を扱つた