【摘要】 用地球的自由振荡研究地球内部结构、速度间断面、密度分布等具有射线理论不可替代的优点。而地球的自由振荡可以用简正振型来表示,用简正振型叠加方法合成的PKP波理论地震图,其PKPab波震相和PKPdf波震相的走时与射线理论计算的理论走时基本一致,并且研究了在地幔底部至核幔边界上方300 km处,压缩波的速度梯度的变化对PKPab波振幅的影响,从而证明当波以接近掠射角或者大于掠射角入射时,会有漏能现象的发生,或者可称之为隧道效应。发现用3个不同模型合成的地震图,在震中距相同的情况下,核幔边界上P波速度梯度大的,其PKPab波的振幅较小一些。这也进一步说明核幔边界上方P波速度梯度的变化对漏能现象有一定程度的影响。更多还原

【Abstract】 The earth free oscillation can be used to constrain structure of the earth interior,including velocity,discontinuity as well as density distribution.Surface wave and body wave can also be implemented by normal modes summation. Synthetics seismograms via normal modes summation agree well in travel times with those from ray theoretical algorithm.We investigate the effects on PKPab amplitudes for three earth models with different P velocity up to 300km above Coremantle boundary.These results suggest that energy can leak into outer core even when P waves turns above core mantle boundary,which is just the case of tunneling effect.更多还原