1. Chapter 12 Section 2
Earthquakes

2. What is an earthquake?
Earthquake- The shaking that results from the movement of rock beneath the Earth’s surface

3. Types of stress
Shearing- stress that pushes a rock in two separate directions
Tension- stretches rock, causing it to become thinner in the middle
Compression- pushes the two plates together until they either fold or break

4. Types of stress

5. Kinds of Faults 1 Fault – crack where movement was
Strike Slip Faults- from shearing
Normal Faults- Footwall rises above hanging wall
Reverse Faults- Hanging wall rises above footwall

6. Normal Fault
Reverse Fault
Strike-Slip Fault

7. Strike-slip faults

8. FOCUS & EPICENTER 2-3
Focus- The point beneath the Earth’s surface where rock breaks under stress and causes an earthquake
Epicenter- The point on the Earth’s surface directly above an earthquake’s focus

15. Triangulation to find the epicenter

17. Epicenters on a larger scale

18. 3 Types of Earthquake Waves 57
(P)rimary waves- push pull waves
(S)econdary waves- side to side waves
(L) Surface waves- up and down rolls
Seismic Waves- Earthquake waves that are compressional and transverse.

19. 1. Primary waves (P-waves) – arrive at a given point before any other type of seismic wave.   (fastest of the three)

20. 2. Secondary Waves (S-waves) – arrive at a given point after the P wave. (second fastest)

21.  3. Surface waves (L-waves) –  slowest moving seismic waves. Arrives last. Most destructive!

24. Seismographs
We use a seismograph to measure/ detect seismic waves

25. Modern day seismographs

28. Ways we measure earthquakes
Mercalli scale- relies on eyewitness accounts
Richter scale- measures ground movement
Moment Magnitude scale- uses both eyewitness accounts and ground movement

29. Major continental U.S. earthquakes

30. How earthquakes cause damage
Loose soil
Can cause landslides or mudslides

31. Liquefaction
Soil and the water that is in it become separated
Because the soil is heavier, it sinks pushing the water to the surface

33. Mudslide and landslide

34. San
Andreas
Fault

35. Why earthquakes in Japan?

36. Building damaged by liquefaction

37. Earthquake damage

39. San Francisco 1906 Earthquake

40. Los Angeles 1994

41. San Francisco 1989

42. Crack in the surface

43. Faults in
California

44. Movement
along a fault

45. Buildings in Japan after earthquake

46. Aftershocks
Movement along a fault that occurs after a larger earthquake along that same fault

47. Tsunamis
Tidal waves that can reach upwards to 115 feet
Caused by Earthquakes that happen deep under water

49. 2004 Sumatra tsunami

50. Tsunami travel time

51. Tsunami height

52. Tsunami in Bangladesh

53. Tsunami damage

54. Days before tsunami
Few minutes before tsunami
During tsunami

55. During an earthquake, how do you protect yourself?
Go under a table
Go under a doorway
Go under steps

56. Earthquake Hazards

57. Earthquake prone areas in the Midwest U.S.

58. How do we monitor movements in the faults?
Creep meters
Laser-ranging devices
Tilt meters
Satellite monitors

59. Creep Meter

60. Fault detecting laser

61. Tilt meter