How do Volcanoes Erupt?
The earth is made up of four layers. In the middle is the solid inner core. Then there is the outer core. As you get closer to the surface, you get to the mantle, made up of molten rock (magma) and gases. On the outside, the ground we are standing on, is the crust. In the mantle, pressure can build up so high that the magma and gases can't be held in any longer. It bursts out onto the earth's surface through weak spots in the crust. After multiple eruptions, layers of ash and lava (magma on the earth's surface), form a cone shaped or gently sloped mountain or hill with a hole or vent in the middle over the place where the magma first broke through the crust. This is a volcano. As volcanoes mature they develop their own magma chamber, connected to the mantle. When again pressure builds, the volcano will erupt the magma and gases.
The tectonic plates play a great part in volcano formation. The plates are sections of the earths crust, which is broken into pieces. Where these plates meet, volcanoes often form. On boundaries where the plates move apart, magma (molten rock and gases), rises to fill the gap in the crust, forming volcanoes that are not very steep and usually erupt runny lava. These volcanos are generally not too dangerous. On boundaries where the plates push together, however, the plate pushing under may melt. But due to the fact that it contains water, the magma it makes is lighter than usual. It rises, forming a volcano liable to violent, gassy eruptions.
However, volcanoes don't just form on plate boundaries. Hot spots are plumes of extra-hot magma that rise and push through the crust, forming a volcano. As the plate over the hot spot moves and the first volcano moves away, a new volcano forms over the hot spot. Over thousands of years, a volcano chain forms.
However, volcanoes don't just form on plate boundaries. Hot spots are plumes of extra-hot magma that rise and push through the crust, forming a volcano. As the plate over the hot spot moves and the first volcano moves away, a new volcano forms over the hot spot. Over thousands of years, a volcano chain forms.