1. Volcanic Eruptions

2. Inside a Volcano All volcanos have a – Magma Chamber Pipe Vent
Side vents
Lava flow
Crater

3. Volcano Eruption These are similar to when you shake a can of soda
Gasses are trapped inside the lava
When magma rises towards the surface the pressure decreases.
When under decreased pressure the gasses expand and form bubbles
These gas bubbles eventually form enough force to cause a volcanic eruption

4. Volcano Eruptions Quite Eruptions Explosive Eruptions
Magma is low in silica, low viscosity
Magma constantly oozes quietly from vent and can travel many kilometers
Main Island of Hawaii was formed from quite eruptions over hundreds of thousands of years
Magma is high in silica, high viscosity
Magma does not constantly erupt so this causes pressure to build up over time.
Gasses cannot escape from the magma so pressure builds until it explodes.
Mount St. Helens is an example. Last erupted in 1980.

5. Volcano Eruptions
Pyroclastic flow- occurs when an explosive eruption hurls out a mixture of hot gases, ash, cinders, and bombs (big pieces of rock).
Can be more dangerous then the lava.

6. Life Cycle of a Volcano
Active volcano- is a volcano that had erupted recently or has shown signs that it might erupt soon.
Dormant volcano- is a volcano that has not erupted in a long time but scientist expect that it should erupt again in the future.
Extinct volcano- is a volcano that is unlikely to erupt ever again.