A volcano is a hole or crack in the ground through which gases, lava & rock are erupted.

Types of volcanoes:
1. Composite Volcano
                -> The lava is viscous & slow.
                -> It flows not far away
                -> The volcano steep sided
2. Shield Volcano
                -> The lava is runny
                -> It flows far away
                -> The volcano is gentle sided

Classification of Volcano
1. Active Volcano: Liable to erupted e.g. Mount Etna
2. Dormant (sleeping) Volcano: Not erupt many years e.g. Mount Pinatubo
3. Extinct Volcano: Not erupt for million years e.g. mount Edinburgh

- Volcanoes form when magma forced up through the crust
- Volcanoes form at destructive, constructive margins & at hotspot.
- At destructive, the melted crust is less dense than the rest of the mantle.
- At constructive, plated move apart & rises to fill the gap.
- At hotspots, a strong upward convection current in the mantle forces magma through.
- Volcanoes are monitor so that scientist can predict when they are likely to erupt.


What Comes Out of A Volcano?
1. Gases: Contains water vapour (50%-80%), causing pressure to build up the magma & explosive.
2. Magma: Molten rock material creates lava in the earth's surface.
3. Solids: Known as pyroclastic material.

Features of Volcanoes?
1. Craters:
                - Circular depressions
                - Less than 1 Km in diameter
                - It sometimes has a crater at the summit
2. Calderas:
                - Huge crater
                - Caused when a volcanic come collapses into a party empty magma chamber after a powerful eruption
                - Yellowstone (USA)

The Danger of Volcanic Eruptions
1. Ash Falls: It blasted into the atmosphere and it can stay for months, it damages buildings & people.
2. Pyroclastic Flows: The hot solid material flows down valley & slopes
3. Lateral Blasts: Sometimes a volcano can explode sideways, which can be very destructive for areas with 40 Km of the volcano. It can destroy houses & property
4. Mudflows (lahars): Those form when ash mixes with water & travels down river valleys. Mud is much denser and very destructive - washing away buildings roads, bridges, and people
5. Volcanic Gases, it contains carbon dioxide and can cause lung diseases.
6. Acid Rain: It contains sulfur dioxide &hydrogen; this can damage buildings, animals’ species & plant.
7. Lava Flows, It destroyed anything around it.