1. Chapter 12 Study Notes
Earthquakes

2. How and Where Earthquakes Happen
Chapter 12 Section 1
How and Where Earthquakes Happen

3. 1
_______ ________is the sudden return of deformed rock to its undeformed shape.
Elastic
rebound

4. 2
The ______ ______ of an earthquake occurs at the focus.
first
motion

5. 3
The _________ of an earthquake is the point on Earth’s _______ directly above the earthquake’s focus.
epicenter
surface

6. 4
A ______ wave is a seismic wave that travels through the _______ of the earth.
body
interior

7. 5
A ________ wave is a seismic wave that travels along the _______ of the earth.
surface
surface

8. 6
P _______ are the ______ body waves.
waves
fastest

9. 7 P waves can travel through ______, ______, and _______. solids
liquids
gases

10. 8
P waves travel _______ through very _____ and not easily ____________ materials.
fastest
rigid
compressed

11. 9
S waves can only travel through ______.
solids

12. 10 Earth’s interior affects the _______ and _______ of seismic waves.
speed
direction

13. 11
A _______ _____ is an area where no direct ______ _____ from a particular earthquake can be detected.
shadow
zone
seismic
waves

14. 12
Earthquakes generally occur at _____ __________ where stress on rocks is the ________.
plate
boundaries
greatest

15. Chapter 12 Section 2
Studying Earthquakes

16. 13 A ___________ is an instrument that records the ground _________.
seismograph
vibrations

17. 14 A modern ____________ consists of _____ sensing devices.
seismograph
three

18. 15 A ___________ displays earthquake motion ________ by a seismograph.
seismogram
recorded

19. 16
Scientists find the _________ of an earthquake by comparing the ______ times of P waves and S waves at _____ or more seismograph stations.
epicenter
arrival
three

20. 17
When seismologists record ______ times of P waves and S waves at three or more seismograph stations, they are looking for the earthquake’s ________.
arrival
epicenter

21. 18 ___________ is a measure of the _________ of an earthquake.
Magnitude
strength

22. 19
The Richter scale is based on ________.
magnitude

23. 20
The Richter scale measures the __________ of an earthquake using _______ ______.
magnitude
ground
motion

24. 21
The moment magnitude scale measures the _________ of an earthquake by the _____ size and the _________ that the fault blocks move.
magnitude
fault
distance

25. 22
The _______ _________ scale measures the _________ of large earthquakes the most ________.
moment
magnitude
magnitude
accurately

26. 23 _______ is the amount of _______ caused by an earthquake. intensity
damage

27. 24 The ________ _______ scale measures the _________ of an earthquake.
modified
Mercalli
intensity

28. 25
Intensity ____ _(___)_on the modified Mercalli scale is described as causing _____ __________.
XII 12
total
destruction

29. Earthquakes and Society
Chapter 12 Section 3
Earthquakes and Society

30. 26
A _______ is a large ocean _____ that forms after a volcanic eruption, underwater earthquake, or landslide.
tsunami
wave

31. 27 As tsunamis move toward shore the waves _______ in _____. increase
height

32. 28
________ _________, __________, and undersea __________ may all cause a tsunami.
Volcanic
eruptions
earthquakes
landslides

33. 29 During a ______ earthquake, buildings may _____ or _______. major
sway
collapse

34. 30
You can prepare for an earthquake by gathering ______, ______, _________, and a portable _____.
food
water
flashlights
radio

35. 31
If you are ________ during an earthquake, you should crouch under _______.
indoors
desk

36. 32
During and after an earthquake you should stay _______ and follow __________.
cautious
instructions

37. 33
A ________ ______ is an area in which strong earthquakes have occurred in the ______.
seismic
gap
past

38. 34
A _________ is a small earthquake that may precede a ______ earthquake.
foreshock
larger

39. 35
Scientists study _______ ____, _____ _______, and __________ in order to predict earthquakes.
seismic
gaps
rock
changes
foreshocks

40. 36
Earthquake ________ is _________.
prediction
unreliable

41. The End