1. Two factors determine the type of eruption :  Amount of water vapor & other gases in the magma  The chemical composition of the magma Types of Volcanic Eruptions

2. Volcanoes SPI 5.2.5 Describe internal forces such as volcanoes, earthquakes, faulting, and plate movements that are responsible for the earth’s major geological features such as mountains, valleys, etc.

3. destructive Rarer but very destructive. Clouds of hot debris, ash, and gas rapidly shoot out. blown into the air Molten rock pieces and ash can be blown into the air. Explosive Eruptions

4. Water content high Water content of the magma is high Explosive Eruptions

5. Silica content high- Silica content of the magma is high- it’s thick, flows slow, and tends to plug vents Enough pressure= explosion! Explosive Eruptions

6. Examples: Mt. St. Helens Mt. Fuji Mt. Pinatubo

7.  Most common calm  Produce relatively calm flows of lava Non-explosive Eruptions

8.  Lower  Lower silica content (thinner lava) Non-explosive

9.  …and has low water content  Examples: Hawaii Non-explosive

10. Video: a typical Hawaiian eruption

11. Shield volcanoes Huge! Made from lava layers Large base, gentle slope Form non-explosive eruptions- runny lava spreads over a large area Life span of a million years or more Example: Hawaii’s Mauna Kea

12. Sketch a shield Volcano:

13. Shield Volcanoes Mauna Kea

14. Shield Volcanoes Mauna Kea

15. Shield volcano on Mars; Taken from space The Mauna Loa volcano in Hawaii— the largest volcano on Earth—has the broad expanse characteristic of shield volcanoes. It spreads across half the island of Hawaii.

16. Cinder cones Made of loose pyroclastic material from moderately explosive eruptions When lava hits the ground, it sticks rather than flows This builds a steep cone with a small base Life span of a few years because they erode away easily Paricutín Example: Mexico’s Paricutín

17. Cinder cones Sketch:

18. Cinder Cones :

20. Composite or strato One of the most common kinds Form from explosive pyroclastic material followed by quieter flows of lava- creates alternating layers Broad bases, sides that get steeper towards the top Life span of a million years or more

21. STrato/Composite : Mt. Fuji in Japan Example: Mt. Fuji in Japan

22. Sketch a composite Volcano:

23. More Composite (strato) Volcanoes : Mt. Rainier

24. Composite/strato volcanoes

25. Video Clip: Types of volcanoes