1. Earthquakes and Volcanoes
C12-17 and C20-25
v.martinez

2. 1. Earthquake
An earthquake is a vibration, or shaking of Earth’s crust.

3. 2. Fault
A fault is a break in the crust along which the rocks move.

4. 3. Focus
The focus is the point underground where the movement first took place.

5. 4. Epicenter
The epicenter is the point on the surface that is right above the focus.

6. 5. Seismograph
A seismograph is an instrument that records earthquake waves.

7. 7. Why do earthquakes occur?
There is a build up and sudden release of energy in rocks.

8. 8. Where do most earthquakes occur?
Most earthquakes occur along faults.

9. 8. The San Andreas Fault
The San Andreas Fault is in California. Dozens of major earthquakes occur here.

10. 9. Volcano
A volcano is a mountain that forms when red-hot melted rock flows through a crack onto the earth’s surface.

11. 10. Magma
Magma is melted rock inside the earth.

12. 11. Lava
Lava is melted rock that reaches the earth’s surface.

13. 12. Vent
The magma flows onto the surface through a rock opening called a vent to form volcanic mountains.

14. 13. Magma Chamber
A magma chamber is an underground pool that holds hot magma.

15. 15. What are the three ways volcanoes form?
1. When two plates collide
2. When two plates separate
3. When plates move over hot spots in the mantle

16. Plates colliding

17. Plates separating

18. Plates moving over hot spots in the mantle