1. Soft Core Spectrum Splitting of the Torsional Oscillation of an Elastic Sphere and Related Problems.

概要

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The torsional oscillation of an earth model consisting of a homogeneous mantle and a soft homogeneous core is studied and the following matters are discussed and proved. (1) When there is a soft core those modes are predominant which have nearly equal frequencies to that of a liquid core model. (2) These modes are very high radial higher modes, and a simple formula that gives the order number of them is presented. (3) Consecutive spectrum lines far stronger than the other ones sometimes have nearly equal amplitudes and frequencies, which fact proves to be a kind of spectrum splitting phenomenon. (4) Depending on the density and rigidity ratios of the core and mantle observable frequency is higher or lower than that of a liquid core model, and there is also a possibility of two spectrum peaks having nearly equal amplitudes. This phenomenon will be of use for the determination of the core rigidity by means of the observation of free oscillation periods.一様なマントルと,一様で軟い核を特つ弾性球の捩れ振動に関して次のことが論ぜられた.1)核の剛性が小さい時には,基本振動周期は極めて長いが,実際に表はれるのは,核が流体の時とほとんど等しい周期をもつた振動である.2)これらの振動は半径方向に多くの節を持つ高次のモードであり,その次数は簡単な公式によつて求めることができる.
1964-05-30