1. Volcanoes & Volcanic Eruptions

2. What is a Volcano?
A volcano is an opening where magma comes to the Earth’s surface.
Magma at the Earth’s surface is called lava.
Lava
Vent
Magma
chamber

3. Example: honey has a higher viscosity than water
Volcanic Eruptions
Not all volcanoes are explosive.
The type of eruption depends on the composition of the volcano’s magma, its viscosity and the amount of dissolved gases.
Viscosity is the resistance to flow.
High viscosity = thicker magma, flows more slowly
Low viscosity = thinner magma, flows quickly
Example: honey has a higher viscosity than water

4. Magma Composition - Explosive
Magma that has high silica content has a higher VISCOSITY and lots of dissolved gases. This type of magma leads to EXPLOSIVE volcanic eruptions.

5. Magma Composition – Non-explosive
Magma that has LOW silica content has a lower VISCOSITY and less dissolved gases. This type of magma is thinner and flows more easily causing NON-EXPLOSIVE eruptions.

6. Non Explosive Eruptions
Quiet eruptions
rivers of red hot lava flow across the surface slowly
Lava is extruded
Example: Hawaii

7. Non-explosive Eruptions
Lava flows slowly out of the volcano’s vent traveling down the sides of the volcano.
Hawaii

8. Explosive Eruptions Debris and gases shoot out at high speeds
No lava flow
Molten material is blown into pieces, some stay in the atmosphere for years!
Pyroclastic material is forced out
Example: Mount Saint Helens in Washington

9. Explosive Eruptions
Lava erupts out of the volcano’s vent sending gases and pyroclastic material into the air.
Mount Saint Helens in Washington

10. Keep these notes in your binder – we will go over them tomorrow
Keep these notes in your binder – we will go over them tomorrow. We will also go over this week’s quiz review 

11. How the Universe Works: Volcanoes
Start Discovery Education Video
“How the Universe Works: Volcanoes”
username: uticascience
password: discovery

13. Brain Pop