The opening happens when melted rock and other substanceshots out of the ground from the center of the Earth. The volcano is usual a coned shaped moutain. The volcano becomes that shape because of lava flowing down the volcano. In most eruptions huge clouds of ash form over the volcano. During an eruption huge pices of red hot rocks shots out of the top of the volcano.
Some eruptions are so powerful that it blows the volcano apart.
Eruptions have caused a lot of deaths by wiping out towns, kigdomes, and much more. The word Volcano comes from Vulcan, the name that the ancient Romans gave to there fire good. Most lava forms 50 to 100 miles beneath the Earth's surface. Lava is a name for magma that has exaped from the Earth's surface. Manley three things come out of a volcano when it erupts, 1.Rock, 2.Lava, and 3.Gas.