Heat from the inside the Earth is called geothermal. Heat produced by radioactive decay of elements such as uranium and thorium in the core and mantle.
How are convection currents made then?
- inner core is deep , under a lot of pressure that it stays solid
- outer core is liquid as it is under less pressure
- heat rises from the core
- =>convection currents in the liquid outer core and mantle.
- convection currents are strong enough to move tectonic plates.
- Radiocativity in the core and mantle is the engine of plate tectonics.