极移的地震激发研究

EARTHQUAKE EXCITATION STUDY OF THE POLAR MOTION

本文采用Harvard目录中1977－1994年间的地震有关参数，及Dahlen计算的地震引起地球惯量矩的变化有关公式，得到由地震引起的极移要比观测值小2个量级．单个地震引起的极漂移呈现随机特性，但它的累积效应却表现出长期的变化，地震引起激发极的运动方向趋向于130—150°E，它与观测极漂移的方向相反．本文这一分析结果将随着观测技术的不断改进及观测精度的提高而得到证实．当考虑地球液核效应时，地震也可能对地球液核自由章动产生影响．我们的分析表明，大地震的这一影响与VLBI检测出的结果相比较，它在观测精度以下．

By use of the fault plane parameters, the location of epicenter as well as the expession given by Dahlen, the accumulative change of equatorial moment of inertia of the Earth for the 1977-1994 data in Harvard Catalogue is estimated in thes paper. The results show that the change of polar motion and polar direction inducd by a single earthquake is independent of the magnitude of earthquake, which is random, but the accumulative effects of polar shift induced by EQ's appear to be non-random and exhibit a secular behaviour.The resultant accumulative direction is towards 130 -150E.This direction is different from that inferred from polar motion observations.When the liquid core of the Earth is taken into account, its free nutation is also influenced by the earthquake.The analysis in mis paper has shown that such an effect as induced by large earthquakes in below the accuracy of observations with the VLBI.