1. EARTHQUAKES AND PLATE TECTONICS
CHAPTER 6 SECTION 1

2. ELASTIC REBOUND THEORY
Rocks on each side of a fault are moving.
Fault is locked, rocks stop moving.
Rocks on each side of a fault are stressed.
Rocks fracture and separate at weakest point.
Rocks return to original shape.

3. Elastic Rebound Theory

4. AFTERSHOCKS
Original earthquake releases energy in the form of vibrations called seismic waves.
These vibrations may increase stress in other rocks along the fault.
The increased stress on these rocks may cause them to fracture and spring back.
The series of smaller tremors are called aftershocks.

5. FOCUS Area along a fault where the slippage first occurs
Focus is beneath the earth’s surface
The epicenter is directly above
The depth of the focus varies

6. FOCUS DEPTH

7. FOCUS DEPTH OF EARTHQUAKES IN WASHINGTON 1977-1996

8. A point on the earth’s surface directly above the focus
EPICENTER
A point on the earth’s surface directly above the focus

9. MAJOR EARTHQUAKE ZONES
Pacific Ring of Fire
Mid-ocean ridges
Eurasian-Melanesian Mountain Belt

10. MAJOR EARTHQUAKES AREAS

11. PUGET SOUND FAULT ZONES

12. Magnitude

13. STRUCTURAL DAMAGE Kobe Earthquake

14. LIQUEFACTION Kobe

15. RECORDING EARTHQUAKES
CHAPTER 6, SECTION 2

16. TYPES OF SEISMIC WAVES
P waves
S waves
L waves

17. P WAVES Fastest wave First recorded on seismograph
Travel through solid and liquid
Cause rock particles to move together and apart along the direction of the waves.

19. S WAVES Second wave to reach seismograph Travels through solids only
Cause rock particles to move at right angles to the direction the wave is traveling

22. L WAVES Slowest moving of the three waves
Also called surface or long waves
Last to be recorded by the seismograph
Travel over the earth’s surface similar to ocean waves
Cause the greatest damage

24. SEISMOGRAPH A device used to measure seismic waves

28. LOCATING THE EPICENTER

31. EARTHQUAKE SCALES
RICHTER
MERCALLI

32. RICHTER SCALE Scale that ranges from 1-10
Each whole number increases the magnitude of the energy 31.7 times
Largest recorded magnitude - 9.5
Above Major earthquake
Between 6 and Moderate earthquake
Between 2.5 and Minor earthquake
Less than Microearthquake

36. MERCALLI SCALE
Measures the intensity of the damaged caused by the earthquake
Scale of I - XII (1-12)

37. I. Not felt except by a very few

38. II. Felt by a very few persons on the upper floors of buildings

39. III. Felt indoors

40. IV. Hanging objects swing

41. V. Felt outdoors

42. VI. Felt by all, many scared and run outdoors

43. VII. Difficult to stand

44. VIII. Damage slight in specially designed structures

45. IX. Damage considerable in specially designed structures

46. X. Ground cracked, rail bent

47. XI. Bridges destroyed, broad fissures in ground

48. XII. Damage total

49. Pacific Northwest Earthquake Information
REQUEST FOR EARTHQUAKE INFORMATION

52. BEFORE - Be prepared DURING - Stay calm AFTER - Stay cautious
EARTHQUAKE SAFETY
BEFORE - Be prepared
DURING - Stay calm
AFTER - Stay cautious

53. ASSIGNMENT
WORKSHEET 6.3
Page 111, #1-5