Seafloor spreading is a process that occurs at mid-ocean ridges where new oceanic crust is formed through volcanic activity and then moves away. Seafloor spreading helps explain continental drift theory and plate tectonics. Seafloor spreading often affects mostly the middle point of an ocean.
Earthquake and Volcano Mapping
Hotspots an area where there is active volcanic activity. They were thought to be caused by a narrow stream of hot mantle from the core boundary called a plume. The latest evidence is pointing to upper-mantle convection as a cause.