Answer:
Volcanic eruption happens when the heated mixture of earth is erupted from underground. It is a short eruption of viscous magma that explodes in relatively small amounts.
It usually occurs due to the fragmentation of the viscous lava that has been pent up inside the dome due to several climatic reasons. It has a very high temperature and the land close to its vicinity is infertile land. Anything the lava touches burns to ashes. Therefore it is recommended that no civilization is to be formed close to a volcano.