Archimedes principle, found by the old Greek mathematician and creator Archimedes, expressing that any object totally or incompletely submerged in a liquid (gas or fluid) very still is followed up on by an upward, power the size of which is equivalent to the heaviness of the liquid dislodged by the body.
The volume of dislodged liquid is identical to the volume of an item completely drenched in a liquid or to that portion of the volume underneath the surface for an article halfway submerged in a fluid. The heaviness of the uprooted bit of the liquid is comparable to the extent of the buoyant force.
The heating on the earth surface is uneven as the rays of the sun are spread unevenly. The heat on the earth will cause the molten rocks to melt down creating volcano. This increased heating will cause movements in the plate.