- A volcano can be simply defined as a rupture or an opening on the crust of a planet like earth. This opening allows hot ash, molten rock and gases to blow off from the underground spaces. Volcanoes generally acquire shape of a mountain. Volcanoes are usually found at places where tectonic plates get converged or diverged. But there existence at a particular place depends upon many environmental and geological factors. Volcanoes can also occur at a place because of hot spots or mantle plumes. Even hotspot volcanoes are very common at other planets of solar system especially on moons and rock based planets.
- Any eruptions are explosive in nature. They produce fragmental rocks from erupting lava and surrounding country rock. Some eruptions are highly explosive and produce fine volcanic ash that rises many kilometers into the atmosphere in enormous eruption columns. Explosive activity also causes widespread ash fall, pyroclastic flows, debris avalanches, landslides, pyroclastic surges, and lahars. Explosivity is usually the result of gases expanding within a viscous lava. Another mechanism for explosions at volcanoes occurs when surface water or ground water enters a magma chamber. These eruptions are likely when a volcano occurs in a wet area or in the sea.