When a part of the earth's upper mantle or lower crust melts, magma forms. ... Although there are several factors triggering a volcanic eruption, three predominate: the buoyancy of the magma, the pressure from the exsolved gases in the magma and the injection of a new batch of magma into an already filled magma chamber.
Answers & Comments
When a part of the earth's upper mantle or lower crust melts, magma forms. ... Although there are several factors triggering a volcanic eruption, three predominate: the buoyancy of the magma, the pressure from the exsolved gases in the magma and the injection of a new batch of magma into an already filled magma chamber.
I hope it will help you