Answer:
Convection currents in the mantle
Step-by-step explanation:
Convection in the mantle is the same as convection in a pot of water on a stove. Convection currents within Earth's mantle form as material near the core heats up. As the core heats the bottom layer of mantle material, particles move more rapidly, decreasing its density and causing it to rise.
Effects
Convection also plays a role in the movement of deep ocean waters and contributes to oceanic currents. Inside Earth, the convection of mantle material is thought to cause the movement of the overriding crustal plates, resulting in events such as earthquakes and volcanic eruptions.
Speed
Estimates of the speed with which Earth's mantle moves range from 1 to 20 cm/year with an average of about 5 cm/year in the case of plate motions to as much as 50 cm/year in hotspots such as the Hawaiian Islands (see Plates, Plumes, And Paradigms (2005) edited by Gillian R.
Direction
Convection currents observed in water rise to the surface and then spread out in both direction. Convection currents in the mantle are thought to operate in the same matter as convection currents in water. ... This shows that the convections currents move outward both right and left after the current reaches the surface.
Heat source
The primary sources of thermal energy for mantle convection are three: (1) internal heating due to the decay of the radioactive isotopes of uranium, thorium, and potassium; (2) the long-term secular cooling of the earth; and (3) heat from the core.