- Craters: It is a pit at the top of a volcanic vent.
- Calderas: It is a large depression more or less circular in plan with diameter several times that of a crater.
- Tephra: All fragmented ejects from the volcanoes.
- Ash: The finest sand-sized tephra
- Lapilli: These are gravel-sized particles either in the molten or solid state.
- Blocks: Cobble or boulder-sized solid ejecta.
- Bombs: A lump of lava thrown out by a volcano.
- Tuff: Layers of volcanic dust and ashes.
- Lahar: A flow of volcanic mud formed by the mixing of water with Volcanic Ash, often taking the destructive power of an avalanche is known as Lahar. The water may be supplied by seasonal rainfall or by the overflow from a Crater-Lake.
