Transcript: The convective motions of the liquid and semi-liquid rock deep within the Earth create enormous stresses on the lithospheric rock that sits just under the crust. The lithosphere is not entirely solid, and it's not entirely liquid. You can consider it like a material like putty, where if you pull it slowly it will stretch and deform; if you pull it quickly it might break. Stresses on the lithosphere sometimes cause it to break or fracture. The result is an earthquake. Places where the lithosphere breaks allow channels by which material that is molten from the interior can emerge. When the molten material is under the Earth’s surface it’s called magma. When it appears on the Earth's surface its called lava. This is the basis of volcanism. Volcanoes occur where the lithosphere stretches or breaks or occasionally where it is thin. The volcanic islands that define the Hawaiian chain are places where the lithosphere is relatively thin, and magma can punch its way out though the surface. The volcanoes of the Earth trace exactly the plates of plate tectonics.