The Global Distribution Of Volcanoes
- Most of the volcanoes are found on plate margins in narrow belts.
- The majority of them are on Destructive plate margins
- Anomalous result are found in Africa in the Atlantic Ocean
- Many volcanoes surround the pacific ocean, known as the ring of fire.
Different types of Volcanoes
1) Composite volcanoes (E.g Mount Fugi in Japan
- Made up of ash and lava which has been cooled and hardened into layers
- The lava is usualy thick and flows down slowly.
- It hardens quickly to form a steep-sided volcano
2) Shield volcanoes ( E.g Mauna Loa on the Hawaiian Islands)
- Made of only lava
- the lava is runny. it flows quickly and spreads over a wide area which then forms a low,flat volcano
3) Dome volcanoes( E.g Mount Pelee in the Caribbean
- Made up of only lava
- the lava is thick. it flows down slowly and hardens quickly, forming a steep-sided volcano.
Volcano: formed at the destructive plate margin
What causes Volcanoes?
Volcanoes are caused by the movement of tectonic plates.
Volcanoes are only found at destructive and conservative plate margins
At destructive plate margins the Oceanic plate (thinner but more dense) goes under the continental plate ( thicker but not as dense) because its more dense.
1) the oceanic plate moves down into the mantle, where it's melted and destroyed.
2) a pool of magma forms
3) The magma rises through the cracks in the crust ( known as vents)
4) The magma erupts onto the surface ( known as lava) forming a volcano.
Volcano: formed at the constructive plate margin
1)On the Constructive Plate Margin plates are moving apeart because of the convection currents.
2) At constructive plate margins the magma rises up into the gap created by the plates moving apart, forming a volcano. the magma cools creating new land.
3) Some volcanoes also form over parts of the mantle that are really hot ( called hotspots) e.g in Hawaii.