1. Earthquakes And Volcanoes
Chapter 4 Lesson 2
Earthquakes
And
Volcanoes

2. Earthquakes

3. Earthquakes
Earthquake – sudden movement of Earth’s crust
The actual place underground where the rocks break producing vibrations is called the focus
The place on the surface directly above the focus is called the epicenter

5. Normal Fault

6. Reverse Fault

7. Strike-Slip Fault

8. San Andreas
Fault

9. Seismic Waves
Originate at the focus and travel outward in all directions
Magnitude – the measure of the amount of energy released by an earthquake
Aftershocks: Are adjustments in the crust after in earthquake

13. Volcano – opening in the Earth’s crust
Eruption – outpouring of melted rock, ash, and gases
Lava – magma that reaches the Earth’s surface
Crater – a
depression around a vent

14. Ring of Fire The ring around the Pacific Ocean that has most of the world’s volcanoes

15. Volcanoes
Quiet
lava
flows

16. Dike – magma that hardens in a vertical crack
Sill – magma that hardens between horizontal layers of earth
Laccolith – magma in a sill that pushes upward
Batholith – large, underground magma formation

18. Types of Volcanoes Shield Volcano Built from layers of lava
Non-explosive eruptions
Not very steep, but can be big

19. Types of Volcanoes Cinder Cone Volcano Built from pyroclastic material
Moderately explosive, short eruptions
Small in size, steep slopes

20. Types of Volcanoes Composite Volcanoes Most common type
Explosive eruptions and lava flow
Built from pyroclastic material AND lava

21. Mt. St. Helen before the explosive eruption

22. Volcanoes

23. Mt. St. Helen after the eruption

24. Island chain – line of volcanic mountains
Hot spot – stationary pool of magma
Island arc – volcanic islands that are made my subducting ocean floor plates

25. Mid-Plate Hotspots