The dynamic mechanism of plate movement remains a mystery till today. To explore the mystery we calculated the large-scale deformations caused by two great circum-Pacific earthquakes, using the dislocation theory in a spherical Earth model. The result showed that the displacement and strain caused by the two events gradually expand from the area surrounding the epicenter to distant places after the earthquake. The steady-state tensile strain covers most of the Pacific Ocean, reducing the difficulty of mid-ocean ridge spreading, thereby promoting plate movement. This study confirms for the first time that there is a two-way relationship between the circum-Pacific earthquake and tectonic plate, and the viscous mantle of Earth plays a vital role in the relationship.