1. Falcon Focus

2. Essential Question

3. Standard 8-3.8 EARTHQUAKES

4. Assessing Prior Knowledge and Relativity What have you heard about earthquakes lately? Why should we study earthquakes?

6. INTRODUCTION http://video.nationalgeographic.com/video/p layer/environment/environment-natural- disasters/earthquakes/earthquake-101.htmlhttp://video.nationalgeographic.com/video/p layer/environment/environment-natural- disasters/earthquakes/earthquake-101.html

7. The definition of an earthquake is… vibrations that cause the breaking of rocks. These vibrations move in all directions through the earth. They begin at a point along a fault.

8. Earthquakes If the __pressure___ or stress becomes too great, the rock breaks at a weak point along the fault and ___energy_____ is released

9. Focus Epicenter

10. aaALONG THE FAULT

11. Parts of the Earthquake The energy spreads outward in all directions as vibrations called ____seismic waves_____. The _focus____ of the earthquake is the point in the crust, or mantle, where energy is released. The _epicenter___ is the point on Earth’s surface directly above the focus; energy that reaches the surface is greatest at this point.

12. Focus – point inside the Earth where an earthquake begins Epicenter – point on Earth’s surface above focus

13. Focus, Epicenter, and Fault

14. RECAP (Take a minute to fill in the blank)

15. ANSWERS Epicenter: is located right above the focus and has the greatest amount of energy Focus: releases the energy (seismic waves) Fault: a break in the Earth’s Crust (is where an earthquake takes place) Seismic waves: is the energy that is being sent out from the focus

16. Use the words above to Label the Following parts of the earthquake.

17. ANSWERS A: FOCUS B: EPICENTER C: FAULT D: SEISMIC WAVES

18. Cause of Earthquakes What Causes an Earthquake? An aftershock is a small earthquake that follows the main earthquake. A foreshock is a small earthquake that often precedes a major earthquake.  Aftershocks and Foreshocks

26. …And that was just a 7.2 on the Richter scale!

30. SEISMIC WAVES 8-3.2Explain how scientists use seismic waves – primary, secondary, and surface waves – and Earth’s magnetic fields to determine the internal structure of Earth.

31. 3 TYPES OF SEISMIC WAVES PRIMARY (P) WAVESPRIMARY (P) WAVES SECONDARY (S) WAVESSECONDARY (S) WAVES SURFACE WAVESSURFACE WAVES CONSIDERED AS BODY WAVES

32. SEISMIC WAVES _SEISMIC WAVES___ are waves generated by an earthquake that travel through the Earth. These waves can cause the ground to move forward, backward, up, down, and even to ripple. Seismic Waves are generated at the __SAME___ time but move in different ways, and at different speeds.

33. Seismic Waves in the Earth http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

34. SEISMIC WAVES Scientists use the principle that the speed and direction of a seismic wave depends on the material it travels through.

35. How does scientist know or study the Earth’s Core? Because of the behavior of these different waves, scientists have indirect evidence for the solid inner core and liquid outer core of Earth because S waves don’t travel through the outer core because it’s a liquid. Also because earthquake waves travel faster through the mantle than through the crust, scientists know that the mantle is denser than the crust.

36. Seismic Waves

37. PRIMARY (P) WAVE First Wave to Move out from the earthquake focus, the point where the energy is released Travel the fastest of the three waves Push and pull rock creating a back-and- forth motion in the direction the wave is moving (known as longitudinal or compressional waves)

38. P WAVES Move through solid and liquid layers of Earth (therefore it can move through all layers)

39. Primary Waves (P Waves) A type of seismic wave that compresses and expands the groundA type of seismic wave that compresses and expands the ground The first wave to arrive at an earthquakeThe first wave to arrive at an earthquake http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

40. Secondary Waves (S Waves) 2 nd wave to Move out from the earthquake focus Move slower than primary waves Move at right angles to primary waves causing rocks to move up and down and side to side (known as transverse wave: perpendicular to the wave motion)

41. S WAVES Can only move through SOLID rock therefore it CAN NOT TRAVEL THROUGH THE OUTER CORE because it is a LIQUID. IT STOPS AT THE OUTER CORE.

42. Secondary Waves (S Waves) A type of seismic wave that moves the ground up and down or side to side http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

43. Comparing Seismic Waves

44. SURFACE WAVES PSForm when P and S waves reach the surfacee SLOWEST BUT MOST DESTRUCTIVE Can cause the ground to shake making rock sway from side to side and roll like an ocean wave

45. SURFACE WAVES Move through solid and liquid layers of Earth (therefore it can move through all layers)

47. Seismic Waves Paths Through the Earth

48. Earth’s Interior Showing P and S Wave Paths

49. Earthquake Waves & Earth’s Interior

50. 8-3.3 Infer an earthquake’s epicenter from seismographic data.

51. Measuring Earthquakes The energy spreads outward in all directions as vibrations called ___Seismic Waves____. Seismic waves can be measured and recorded by a ____seismograph_______.

52. SEISMOGRAPH

53. Measuring Earthquakes P and SThe vibration record, called a seismogram, looks like jagged lines on paper. Measuring the time between the arrival of the P and S waves determines the distance between the recording seismograph and the earthquake epicenter.

54. SEISMOGRAM

55. Seismograph

56. Types of Seismographs

58. Seismogram Printout

59. How to find the S-P INTERVALS

60. To find the S-P intervals, you have to subtract the P Wave from the S Wave. Measuring the time between the arrival of the P and S waves determines the distance between the recording seismograph and the earthquake epicenter.

61. Find the S-P interval: Show your steps.

62. PRACTICE

63. WHAT IS THE S-P INTERVAL?

65. Locating an Earthquake

66. Locating an Earthquake Epicenter TriangulateTriangulate means to use three positions to determine an exact location.

67. TRIANGULATION identifies the epicenter of an earthquake. The location of an earthquake’s epicenter is found by plotting 3 circles on a map from the records of three seismograph stations and finding the point where the three circles intersect. Note where the 3 circles meet is where the epicenter is located.

68. Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

69. Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

70. Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

71. Triangulation of 3 stations to locate earthquake epicenter

72. Earthquakes are measured using the Richter Scale. The strongest earthquake ever measured was a 9.5 on the Richter Scale. This is a measurement of the amount of energy released from the earthquake.

73. How are Earthquakes Measured? Richter Scale

74. HOMEWORK