Respuesta :

amelia18
"Because it is lighter than the solid rock around it , magma rises and collects in magma chambers . Eventually some of the magma pushes through the vents and fissures in the earth's surface ".
And then a volcanic eruption occurs
-Quora
ramose4367
Volcanoes occur because of the position of the crust over a plate boundary or a 'hot spot' in the Earth's mantle. Continental volcanoes form when subducted crust melts to magma against the mantle, then is forced upward under pressure through cracks in the rocks above.