1. Plate Tectonics, Earthquakes, and Volcanoes Study Guide

2. Diagram of layers of Earth

3. 2) Describe the layers.
Inner core: solid nickel and iron, 10,000 degrees F
Outer core: liquid nickel and iron
Mantle: partially melted in some areas, solid in others due to the pressure, degrees C
Asthenosphere: weak, easily deformed rock (like putty), in the upper mantle
Lithosphere: floats on the asthenosphere, includes the crust and part of the upper mantle
Crust: outer most layer of the Earth, thinnest layer

4. 3) What is plate tectonics?
Plate tectonics is the theory scientists use that explains the movement of the plates.

5. 4) Who came up with the theory of continental drift and plate tectonics?
Alfred Wegener came up with the theory of plate tectonics and continental drift.

6. 5) What are the major plates named after?
Plates are named after the continents and oceans that they carry.
Pacific Plate, North American Plate, …

7. 6) Why do the plates move?
Plates move because of the convection currents in the mantle.

8. LESSON 2

9. 1) What are divergent boundaries? What are they caused by?
Divergent boundaries are where two plates move apart/away from each other.
Magma rises up through a rift and spreads the plates apart.

10. 2) What is a rift?
A rift is a deep valley formed where 2 plates move apart.

11. 3) What is the mid-ocean ridge?
The mid-ocean ridge is a chain of mountains through the oceans where most divergent boundaries are located.

12. 4) What is sea-floor spreading?
Sea-floor spreading is when magma is pushed up through cracks in the rift and cools to form new sea floor.

13. 5) Where is the older oceanic crust?
Older oceanic crust is found further away from rifts, newer crust is found near the rift.

14. 6) What are convergent boundaries?
Convergent boundaries are where two plates are colliding.
Subduction occurs

15. What forms at convergent boundaries?
Mountains, volcanoes, trenches, and (sometimes) earthquakes occur at convergent boundaries.

16. What are transform fault boundaries?
Transform fault boundaries are where two plates grind past one another.

17. What are common along transform fault boundaries?
Earthquakes are common along transform fault boundaries.

18. What is the San Andreas Fault?
The San Andreas Fault is a famous transform fault in California where the Pacific Plate moves past the North American Plate.

19. What will happen to part of California in the future?
The part west of the fault will detach from the US. It could possibly become an island in the Pacific Ocean and could one day be near Alaska.

20. What is Pangea?
Pangea was a supercontinent formed 225 million years ago.

21. What does Pangea provide evidence for?
Pangea provides evidence for continental drift because it shows how the continents were all connected at one point in time.

22. 14) Will the Earth look the same 200 billion years from now?
No, the Earth will not look the same in 200 million years because the plates are constantly moving. The continents will be in different places, new oceans could form, current oceans could disappear, new land could form, current land could disappear.

23. 15) How were the Appalachian Mountains formed if they aren’t near a plate boundary?
The Appalachian Mountains were formed when the plates carrying Africa and North America were once colliding millions of years ago.

24. 16) How do Earth’s plates affect the positions of the continents?
Since the plates are constantly moving the continents are also moving. Over long periods of time you can see big shifts in their locations.

25. LESSON 3

26. 1) Explain how earthquakes occur.
As two plates move against each other, the rocks lock together and bend until eventually they can’t bend anymore. The rocks break and release a ton of energy in the form of an earthquake.

27. 2) What is the difference between the focus and the epicenter?
The focus in in the Earth’s crust where the first major movement occurs. The epicenter is on the surface directly above the focus.

28. 3) What are P waves?
P waves are primary waves. P waves arrive first and are “push, pull” waves. They are faster.

29. 4) What are S waves?
S waves are secondary waves and arrive second because they are slower. S waves move in right angles to the waves direction of travel.

30. 5) What are surface waves?
Surface waves travel on the surface and make the ground roll and sway. Surface waves cause the damage during an earthquake.

31. 6) Which waves cause the most damage?
Surface waves cause the most damage during an earthquake.

32. 7) Which waves are the fastest?
P waves are the fastest waves.

33. 8) What does the Richter Scale measure?
The Richter Scale measures the amount of energy released during an earthquake.

34. 9) What does the Moment Magnitude Scale measure?
The moment magnitude scale more accurately measures the energy released by an earthquake.

35. 10) What does the Mercalli Scale measure?
The Mercalli scale measures the amount of damage an earthquake causes.

36. 11) How does the intensity of an earthquake change the further you are from the epicenter?
The intensity of an earthquake decreases the further you are from the epicenter.

37. 12) Are there more major or minor earthquakes each year?
There are more earthquakes each year that cause little to no damage than major damage.

38. 13) How are volcanoes useful?
Volcanoes are useful because they are a natural source of heat and they create land.

39. 14) Along what types of plate boundaries do most volcanoes occur?
Most volcanoes occur along divergent boundaries and convergent boundaries.

40. 15) What is the Ring of Fire?
The Ring of Fire is a chain of volcanoes surrounding the Pacific Ocean Plate

41. 16) How does a hot spot create a volcano?
A hot spot creates a volcano by a column of magma breaking through the lithosphere.

42. 17) How were the Hawaiian Islands formed?
The Hawaiian Islands were formed by a hot spot in the Pacific Plate. Since the plates are always moving, a chain of volcanoes forms as the plate moves across the hot spot.

43. Shield Cinder Cone: Composite:
broad, slightly domed shape
World’s largest volcanoes
Cinder Cone:
Erupts for a short period of time
No taller than 300 m
Composite:
Switches between quiet and violent eruptions
Gentle eruptions
Erupt for a long period of time
Volcanoes, lava flows
Violent eruptions
Ash falls
Cone shape