A volcano is an opening or vent in the Earth's crust (or the crust of another planetary body) through which molten rock (lava), volcanic ash, and gases escape from beneath the surface
. This process is driven by pressure from gases dissolved in magma (molten rock beneath the surface), which force the material upward until it erupts out of the vent
. Volcanoes can take different forms, including cinder cones, shield volcanoes, stratovolcanoes (composite volcanoes), and lava domes, depending on the characteristics of the erupted materials and the eruption style
. They are most commonly found at tectonic plate boundaries, such as where plates are diverging or converging, but can also form away from plate boundaries due to mantle plumes (hotspots), as seen in places like Hawaii
. In summary:
- A volcano is an opening in the crust where magma, ash, and gases escape
- Eruptions can be explosive or non-explosive, depending on the magma's composition and gas content
- Volcanoes play a major role in shaping planetary surfaces but can also cause significant hazards to life and property
