The document discusses earthquakes and related topics in three main sections. Section one describes how earthquakes are caused by movement along tectonic plate boundaries and outlines the different types of seismic waves generated by earthquakes. Section two explains how earthquakes are measured, located and recorded using seismographs. Section three discusses the damage earthquakes can cause to buildings and properties from ground shaking and liquefaction. It also describes tsunamis and provides safety tips for earthquake preparedness.

1. Earthquakes
Outline
1Earthquakes and Plate Tectonics
2Types of Seismic Waves
Recording Earthquakes
Measuring Earthquakes
Locating an Earthquake
3Destruction to Buildings and Properties
Tsunamis
Earthquake Safety
Earthquake Warnings and Predictions

2. 1

3. Earthquakes are vibrations in the earth’s
crust
The movement between plate and along faults is not smooth
They move in jerks, giving rise to earthquakes. The locations of
earthquakes throughout the world exist along the major tectonic
boundaries. An earthquake is a sudden shaking of the ground.
They generate seismic waves.

4. Stress and Strain
• stress – total force
acting on crustal
rocks per unit area
• strain – deformation
of materials in
response to stress
• elastic deformation
• plastic deformation

5. Earthquake Vocab
• Focus
• Epicenter
• Fault

7. Focus – Area where slippage first occurs

8. Earthquakes create seismic waves which shake the ground
as they pass. Earthquakes create waves just like waves of
water moving across the ocean.

9. Consider what happens when a drop of rain hits a pond of water.
The drop disturbs the flat surface of the water and creates waves
that travel outward in all directions from the disturbance. These
waves travel on the surface of the pond, along the interface
between the water and the air.

10. FAULTS
Distant forces cause a
gradual build up of stress
in the earth over tens or
hundreds or thousands of
years, slowly distorting
the earth underneath our
feet. Eventually, a
pre-existing weakness in
the earth--called a fault or
a fault zone--can not resist
the strain any longer and
fails catastrophically.
San Andreas Fault

11. Stresses

12. Connection to Plate Tectonics
• What type of boundary causes tension?
• divergent
• What type of boundary causes
compression?
• convergent
• What type of boundary causes shear?
• transform

13. Mid-Ocean Ridges
This is a map of the major oceanic spreading centers.

14. Types of Faults
Reverse (convergent)
• Compression causes
horizontal and vertical
movement
• Where might this occur
(real-world example)?
Normal (divergent)
• Tension causes
horizontal and vertical
movement
Where might this occur
(real-world example)?

15. Types of Faults
Strike-slip (transform)
• Shear causes horizontal
movement
• Where might this occur
(real-world example)?

16. Fault Zones
Faults are narrow zones in
the Earth, usually extending
no more than about 10
miles deep, which separate
rigid crustal blocks.
A well known fault is the
San Andreas Fault which
separates the Pacific plate
from the North American
plate.

17. California Faults
• http://www.pbslearningmedia.org/resource/ess

18. The Pacific plate
is moving to the
northwest at a
rate of about 4
inches per year.

19. 2
• Types of Seismic Waves
• Recording Earthquakes
• Locating Earthquakes

20. Types of Seismic Waves
Earthquakes generate three major types of
seismic waves
P, for "Primary"
S, for "Secondary" waves
L, for “Long” waves

21. P Waves - Primary
Move the fastest and are the first recorded by a
seismographic
Can travel through liquids and solids
The P waves move in a compressional motion
similar to the motion of a slinky

22. S Waves - Secondary
Secondary Waves are the second to be
recorded by a seismograph,
Can only travel through solid materials
S waves move in a shear motion perpendicular to
the direction the wave is traveling.

23. L Waves – Long Waves or Surface
Waves
Surface or L waves occur only in the earth's crust
and cause the most damage
travel along the surface of the earth from the point
directly above the quake or epicenter
Slowest moving waves, last to be recorded by a
seismograph.

24. Recording Earthquakes
An earthquake is a sudden shaking of the ground. They
generate seismic waves which can be recorded on a sensitive
instrument called a seismograph.

25. Advances in
seismograph
technology have
increased our
understanding of
both earthquakes
and the Earth
itself.

26. Perhaps the earliest seismograph was invented in China A.D.
136 by a man named Choko.

27. The Seismograph
• http://www.pbslearningmedia.org/resource/ess

28. Earthquake Measurement
Richter Scale expresses
the magnitude or measure
of energy released by an
earthquake.
Mercalli scale expresses
the intensity of an
earthquake or the
amount of damage it
causes.

29. I. Instrumental
II. Feeble
III. Slight
IV. Moderate
V. Rather strong
VI. Strong
VII. Very strong
VIII. Destructive
IX. Ruinous
X.Disastrous
Detected only by seismographs
Noticed only by sensitive people.
Resembling vibrations caused by heavy traffic.
Felt by people walking; rocking
of free standing objects.
Sleepers awakened and bells ring.
Trees sway, some damage from
overturning and falling objects.
General alarm, cracking of walls.
Chimneys fall and there is some
damage to buildings.
Ground begins to crack, houses
begin to collapse and pipes break.
Ground badly cracked and many
buildings are destroyed.
There are some landslides.
XI.Very Disastrous Few buildings remain standing;
bridges and railways destroyed;
water, gas, electricity and
telephones out of action.
XII.Catastrophic
Total destruction; objects are
thrown into the air, much heaving,
shaking and distortion of the ground.
The Modified
Mercalli
Scale

30. Richter Scale
Magnitude
2.5 or less
2.5 to 5.4
5.5 to 6.0
6.1 to 6.9
7.0 to 7.9
8.0 or greater
Earthquake Effects
Usually not felt, but can be recorded by seismograph.
Often felt, but only causes minor damage.
Slight damage to buildings and other structures.
May cause a lot of damage in very populated areas.
Major earthquake. Serious damage.
Great earthquake. Can totally destroy communities near the epicenter.
The Richter magnitudes are based on a logarithmic scale
(base 10). What this means is that for each whole
number you go up on the Richter scale, the energy
released by the earthquake goes up ten times

31. Richter Magnitude How many kilograms of TNT would have this much energy?
0
1.0
2.0
3.0
0.6
20
600
20 000
4.0
60 000
5.0
20 000 000
6.0
60 000 000
7.0
20 billion
8.0
60 billion
9.0
20 trillion
*
*
*
*
*
*
*
*
*
*
*
*
*
*
Smallest quake people can normally feel
Most people near epicenter feel the quake
Nearly 100, 000 occur every year of size 2.5 - 3.0
A small fission atomic bomb
Quakes above 4.5 can cause local damage
A standard fission bomb, similar to the first bomb
tested in New Mexico, U.S.
A hydrogen bomb; can cause great damage locally
About 100 shallow quakes of size 6.0 every year
Major earthquake; about 14 every year
Enough energy to heat New York City for 1 year
Large enough to be detected all over globe
Largest known: 8.9 in Japan and in Chile/Ecuador
San Francisco destroyed by 8.25 in 1906
Roughly the world’s energy usage in a year

32. Locating an Earthquake
The point beneath the Earth's surface where the rocks
break and move is called the focus. The focus is the
underground point of origin of an earthquake. Directly
above the focus, on the Earth's surface, is the epicenter.
Earthquake waves reach the epicenter first. The most
violent shaking is found at the epicenter.

33. Epicenter
Focus

34. Scientist must
have information
from three
seismographic
stations at
different
locations to plot
the epicenter of
an earthquake

35. Need readings
from three
seismic
centers to
locate
epicenter. The
epicenter is
the point at
which the
circles
intersect.

36. Three Major Earthquake Zones
Pacific Ring of Fire

37. New Madrid Earthquake
December of 1811, the largest earthquake ever recorded in American
History started. This earthquake, called the New Madrid Earthquake
because of its primary location on the New Madrid Fault, near New Madrid,
Missouri. From the effects of the 1811-1812 earthquakes, it can be estimated
that they had a magnitude of 8.0 or higher on the not yet invented Richter
scale. Large areas sank into the earth, new lakes were formed, and the
Mississippi River changed its course due to the earthquakes.

38. Review
1.
What instrument is used to record seismic
waves?
2.
Explain the three types of seismic waves.
3. How is the epicenter of an earthquake
located?
4.
How do scientist measure the magnitude of
an earthquake?

39. Earthquake Damage
Earthquakes are among the most powerful events
on earth, and their results can be terrifying.

40. 3
• Destruction to Buildings and
Properties
Tsunamis
Earthquake Safety
Earthquake
Warnings and Predictions

41. Earthquake Destruction
important factors:
Intensity & duration of shaking
Soil type (soft? hard rock?)
Building design

42. 1964 Valdez, Alaska
• http://www.pbslearningmedia.org/resource/ean

43. Tsunami damage:
Alaska 1964 earthquake

44. Intensity
One way of
describing the size
of an earthquake is
by the amount of
shaking at some
particular location.

45. Duration
Length of time the earthquake lasts.

46. other effects
Liquifaction
Liquefaction essentially
means that the soil is turned
into liquid.
The liquified solid then
flows and causes severe
damage to buildings and
infrastructure

47. Liquifaction
Water-saturated, well sorted, fine grain sands and
silts behave as fluids rather than solids.

48. other effects
A tsunami
(pronounced
tsoo-nah-mee) is
a wave train, or
series of waves,
generated in a
body of water
by an impulsive
disturbance that
vertically
displaces the
water column.
Tsunamis

49. Tsunami
is a
Big Wave
Tsunami from Chile earthquake 1960
Magnitude 9.5

50. Tsunami damage in Hawaii :
From 1960 Chile earthquake,
15 hours later

51. Earthquake Safety
Stocking up now on emergency
supplies can add to your safety and
comfort during and after an
earthquake. Store enough supplies
for at least 72 hours.

52. Water: 1 gallon per person per day (a week's
supply of water is preferable)
Water purification kit
First aid kit, freshly stocked
First aid book
Food
Can opener (non-electric)
Blankets or sleeping bags
Portable radio, flashlight and spare batteries
Essential medication
Extra pair of eyeglasses
Extra pair of house and car keys
Fire extinguisher : A-B-C type
Food, water and restraint (leash or carrier) for
pets
Cash and change
Baby supplies: formula, bottle, pacifier, soap
and baby powder, clothing, blankets, baby
wipes, disposable diapers, canned food and
juices.

53. Stay Calm
If You Are Indoors
Protect yourself from falling debris by
standing in a doorway or crouching under a
desk or table.

54. If You Are In An Automobile
Stay away from power lines, tunnels, tall buildings,
and bridges, and stay in car until the tremors cease.

55. After an earthquake be cautious
Check for fire and fire hazards.
Watch for broken glass
Avoid downed power lines

56. Earthquake Warnings and Predictions
Earliest means of
prediction was animal
behavior
Using records of past
earthquakes

57. Scientists are trying to make more accurate
predictions by detecting changes in the
earth’s crust.
Faults have been located and mapped
Instruments placed
along faults measure
small changes in rock
movement.

58. Seismic Gaps – Zones of immobile
rock along faults
Scientists think that
seismic gaps, where the
fault is locked and
unable to move, are the
locations of future
earthquakes

59. Other Warnings
Slight tilting of the ground
Detect strain and cracks caused by stress
Change in magnetic and electrical
properties of rock
Detect natural gas seepage
Local P waves slow down

60. Tests at Rangely, Colorado
Injected water
along a fault
which reduced
friction and the
earthquakes
were less
severe

61. Forecasting EQ’s
• http://www.pbslearningmedia.org/resource/nvs

62. Section 6:3 Review
1. How do tall buildings usually respond during a major
earthquake?
2. What causes tsunamis?
3. What should you do if an earthquake strikes while
you are at home? In a car?
4. What are some early warning signs of earthquake
activity?
5. What type of building construction and location
regulations should be included in the building code of
a city located near an active fault?