QUANTITATIVE ANALYSIS OF THE SLOWING EXPANSION IN THE SOUTHERN HEMISPHERE
南半球减速膨胀的定量分析

The closed differences of the latitude length changing rates at the latitude-circle direction in the Southern Hemisphere and the convergent and spreading rates at global active plate boundaries are obtained from space geodetic data spanning 20 years. Comparing these results with NUVEL1A predictions averaged the past 3Ma shows that: (1) the closed differences of the latitude length changing rates at the latitude-circle direction in the South Hemisphere are all positive; (2) 91 percent of sites in the Southern Hemisphere move up vertically, except several sites near the equator region; (3) the present-day spreading and convergent rates at active plate boundaries in the Southern Hemisphere are systemically smaller than NUVEL1A predictions averaged 3Ma, while the changes of relative motions in the North Hemisphere are disorderly and unsystematic. All these show the present-day motion characteristics of the Southern Hemisphere that is expanding with a slowing down trend.