摘要
1 Studies of seismic excitation of the polar motion The earth’s rotation varies slightly with time. The 3-D earth rotation variation canbe conveniently separated into two components: i) the 1-D variation in the spin rate, oftenexpressed in terms of the length-of-day variation, ii) the 2-D variation in the rotational axisorientation, known as the polar motion as seen in the terrestrial referenee frame.
