2. earthquake: shaking and trembling that results from sudden movement of part of the Earth’s crust
Caused by release of energy (lithospheric plates)

3. Causes of earthquakes:
ground shakes from erupting volcano
collapse of a cavern
impact of meteor
major cause- stress that builds up and causes faulting

5. Elastic rebound theory: rocks that are strained past a certain point will fracture and NOT spring back to their original shape

7. focus: point beneath the Earth’s surface where the rocks break or move apart
Point on fault plane where 1st movement occurs

8. epicenter: point on Earth’s surface directly above the focus
site of most violent shaking

9. How deep in the Earth an earthquake occurs depends on the kind of plate boundary

10. Types of Seismic Waves:
P waves (primary):
move fastest
back and forth waves
move through solid, liquid or gas
push-pull waves

13. Types of Seismic Waves:
S waves (secondary):
travel slower
move up and down
travel through solids ONLY

18. Seismograph: instrument that detects and measures seismic waves

20. Seismogram:seismograph’s record of waves; has wavy lines recorded on paper

21. Measuring Earthquakes
 Earthquake Distance
• The epicenter is located using the difference in the arrival times between P and S wave recordings, which are related to distance.

22. Earthquake Distance

23. Measuring Earthquakes
 Earthquake Strength
• Magnitude- amount of energy released at the earthquakes epicenter
Richter scale: measures how much energy an earthquake releases by assigning a number from 1 to 10

25. Earthquake Strength

27. Measuring Earthquakes
 Earthquake Strength
• Intensity- effect of an earthquake on the Earth's surface
Mercalli Scale: measures the effect of an earthquake; scale based on how the effects of an earthquake are felt

29.  Earthquake Direction
Tracing made by a seismograph can be used to tell how far away an earthquake’s epicenter is from the station that recorded it:
Need distance from 3 different stations in order to determine location
Point where all 3 circles meet is location of epicenter

31. Blue primary waves followed by red secondary waves move outward in concentric circles from the epicenter of an earthquake off British Columbia and Washington State.

32. Locating an Earthquake

33. Some Notable Earthquakes

35. Pacific Ring of Fire: major earthquake zone that forms a ring around the Pacific Ocean

37. Indian Ocean Earthquake
December 26, 2004

38. Earthquakes May Cause... Building collapse Landslides Fire
Liquefaction
Tsunamis

39. Liquefaction
conversion of soil into a fluidlike mass during an earthquake or seismic event
Liquefaction Animation

40. Tsunami
Extremely large ocean wave caused by an earthquake on or near the ocean floor

41. Tsunami

42. Successful earthquake prediction must correctly forecast:
where it will occur
when it will occur
what magnitude it will be

43. Possible methods for prediction:
microquakes
behavior of animals
detect slight tilting of ground before an earthquake
natural gas seepage