Volcanoes Are Found At Destrucive And Constructive Plate Margins
1) At destructive plate margins the oceanic plate goes under the continental palte because it's more dense (This also creates an ocean trench.):
- The oceanic plate moves down into the mantle, where it's meltred and desroyed.
- A pool of magma forms.
- The magma rises through cracks in the crust called vents.
- The magma erupts onto the surface (where it's called lava) forming a volcano.
2) At constructive margins the magma rises up into the gap created by the plates moving apart, forming a volcano.
3) Some volcanoes also form over parts of the mantle that are really hot (called hotspots) e.g. in Hawaii.
Types Of Volcano
There Are Different Types Of Volcano
1) Composite volcanoes (E.g. Mount Fuki in Japan) - made up of ash and lava thats erupted, cooled and hardened into layers. The lava is usually thick and flows slowly. It hardens quickly to form a steep sided volcano.
2) Shield volcanoes (E.g. Mauna Loa on the Hawaiian islands) -made up of only laca. The lawa is runny, it flows quickly and spreads over a wide area, forming a low, flat volcano.
3) Dome volcanoes (E.g. Mount Pelee in the Caribbean) - Made up of only lava. The lawa is thick, it flows slowly and hardens quickly, forming a steep-sided volcano.
Scientists Try To Predict Volcanic Eruptions In Advance
Millions of people live in places where volcanic eruptions can happen. With so many lives at risk, it's important to try to predict eruptions, so teh damage caused can be minimised.
Scientists can moniter the tell-tale signs that come before a volcanic eruption. Things such as tiny earthquakes, escaping gas, and changes in the shape of the volcano (e.g. bulges in the land where magma has built up under it) all mean an eruption is likely.