中文摘要：

高密度内核相对于地幔的晃动将改变地球内部物质的密度分布并导致地球主惯性矩随时间变化。本文在重力场球谐分析理论的基础上，给出了时变的地球主惯性矩A、B、C及主惯性轴，并研究了内核晃动对A、B、C的时变性影响。计算结果表明，A、B、C平均每年增大约4．5×10^27kg m^2，而内核晃动使A、B、C均表现出振幅为10^22～10^24kg m^2的似正弦式变化，不足以维持其长期增大趋势，这进一步支持了“地球在膨胀”的结论。

英文摘要：

The wobble of the high-density inner core, relative to the mantle, will cause a mass redistribution and then a variation in the Earth＇ s principle moments of inertia. Based on the harmonic analysis of the gravity field, the Earth＇ s temporal principal axes and principle moments of inertia A, B and C, as well as the time-dependent variations in A, B and C caused by the inner core wobble, are presented. Numerical results show that, A, B and C have in average annual increments about 4. 5 × 10^27 kg m^2, while the inner core wobble only gives rise to sine-like fluctuations in A, B and C, with maximal amplitudes around 10^22 - 10^24 kg m^2. This further supports the conclusion that the Earth is expanding.