summit - n. the highest point of a mountain : the top of a mountain

crater - n. the area on top of a volcano that is shaped like a bowl

lava - n. melted rock from a volcano

vent - n. an opening through which air, steam, smoke, liquid, etc., can go into or out of a room, machine, or container

magma - n. hot liquid rock below the surface of the Earth

channel - n. a path, tube, or long narrow place where water flows

rapid - adj. happening in a short amount of time