1. Warm Up #16
Where does lava come from? What happens to lava at Earth’s surface after it erupts from a volcano?

2. Ch. 3 Earthquakes and volcanoes
Lesson 2: Volcanoes

3. Essential Questions How do volcanoes form?
What factors contribute to the eruption style of a volcano?
How are volcanoes classified?

4. What determines the shape of a volcano? ACTIVITY
Not all volcanoes look the same. The location of a volcano and the magma chemistry play an important part in determining the shape of a volcano.
Obtain a try, a beaker of sand, a beaker with a mixture of flour and water, waxed paper, and a plastic spoon.
Lay wax paper inside the tray
Hold beaker of sand about 30cm above the tray and slowly pour sand onto wax paper.
What do you notice?
Fold paper in half and careful pour sand back into the beaker.
Stir flour and water mixture so it’s like oatmeal consistency.
Hold beaker about 30cm above the tray and slowly pour flour and water mixture onto wax paper.

5. What is a volcano?
Volcano – a vent in Earth’s crust through which melted – or molten – rock flows
Magma – molten rock below Earth’s surface
Why does magma rise?
What’s Science Got to do With It? – Video online resource

6. How do volcanoes form?
Lava – molten rock that erupts onto Earth’s surface
More than 60% of all volcanic activity on Earth occurs along mid-ocean
ridges
Hot spots – volcanoes that are not associated with plate boundaries

7. Types of Volcanoes What determines the shape of a volcano?
What are the 4 types of volcanoes?

8. Types of Volcanoes What determines the shape of a volcano?
Composition of magma and eruptive style contribute to the shape of a volcano
What are the 4 types of volcanoes?
Shield, composite, cinder, and super

9. Types of Volcanoes
Shield volcanoes – common along divergent plate boundaries and oceanic hot spots
Large with gentle slopes of basaltic lavas
Composite volcanoes – large, steep-sided
volcanoes that result from explosive eruptions of
andesitic and rhyolitic lava and ask along
convergent plate boundaries
Cinder cones – small, steep-sided volcanoes that
erupt gas-rich basaltic lavas

10. Types of Volcanoes

11. Volcanic Eruptions
Volcanic ash – tiny particles of pulverized volcanic rock and glass-high into the atmosphere
Explosive behavior is affected by the amount of dissolved gases, specifically the amount of water vapor that magma contains and silica content of magma
Differences in silica amounts affect magma thickness and viscosity – a liquid’s resistance to flow
Dissolved gases contribute to how explosive volcanos can be
Gases include water vapor, small amounts of carbon dioxide, and sulfur dioxide

12. Predicting Volcanic Eruptions
Moving magma can cause ground deformation, a change in the volcano shape, a series of earthquakes, volcanic gas emissions can increase, and ground and surface water near the volcano can become more acidic
How do volcanoes affect climate?