Volcanism
![Plate tectonics map with volcano locations indicated with red circles](/Images/godic/202502/08/Plate_tectonics_map3448.gif")
![Three types of plate boundary.](/Images/godic/202502/08/Tectonic_plate_boundaries3448.png")
![Cross-section through a stratovolcano (vertical scale is exaggerated):
1. Large magma chamber2. Bedrock3. Conduit (pipe)4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank
9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15. Ash cloud](/Images/godic/202502/08/Volcano_scheme.svg3448.png")
![Types of Intrusion 1) Laccolith, 2) small Dike, 3) Pluton/Batholith, 4) Dike, 5) Sill, 6) Pipe/Volcanic neck, and 7) Lopolith](/Images/godic/202502/08/Intrusion_types.svg3448.png")
Volcanism is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics and volcanic gases erupt through a break in the surface called a vent. It includes all phenomena resulting from and causing magma within the crust or mantle of the body, to rise through the crust and form volcanic rocks on the surface.