Elastic- material is compressed bent or stretched and material will return to original form after stress is removed Plastic – permanent deformation
Safer in a field than a building
Many buildings not made to withstand EQ Type of ground underneath effects the building above in a EQ
1Earthquakes and Plate Tectonics
2Types of Seismic Waves
Locating an Earthquake
3Destruction to Buildings and Properties
Earthquake Warnings and Predictions
3. Earthquakes are vibrations in the earth’s
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
6. Focus – Area where slippage first occurs
7. Earthquakes create seismic waves which shake the ground
as they pass. Earthquakes create waves just like waves of
water moving across the ocean.
8. 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.
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
San Andreas Fault
11. Connection to Plate Tectonics
• What type of boundary causes tension?
• What type of boundary causes
• What type of boundary causes shear?
12. Mid-Ocean Ridges
This is a map of the major oceanic spreading centers.
13. Types of Faults
• Compression causes
horizontal and vertical
• Where might this occur
• Tension causes
horizontal and vertical
Where might this occur
14. Types of Faults
• Shear causes horizontal
• Where might this occur
15. 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
16. California Faults
17. The Pacific plate
is moving to the
northwest at a
rate of about 4
inches per year.
19. Types of Seismic Waves
Earthquakes generate three major types of
P, for "Primary"
S, for "Secondary" waves
L, for “Long” waves
20. P Waves - Primary
Move the fastest and are the first recorded by a
Can travel through liquids and solids
The P waves move in a compressional motion
similar to the motion of a slinky
21. 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.
22. L Waves – Long Waves or Surface
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
23. 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.
24. Advances in
and the Earth
25. Perhaps the earliest seismograph was invented in China A.D.
136 by a man named Choko.
26. The Seismograph
27. Earthquake Measurement
Richter Scale expresses
the magnitude or measure
of energy released by an
Mercalli scale expresses
the intensity of an
earthquake or the
amount of damage it
28. I. Instrumental
V. Rather strong
VII. Very strong
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.
Total destruction; objects are
thrown into the air, much heaving,
shaking and distortion of the ground.
29. Richter Scale
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
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
30. Richter Magnitude How many kilograms of TNT would have this much energy?
20 000 000
60 000 000
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
31. 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. Scientist must
locations to plot
the epicenter of
34. Need readings
the point at
35. Three Major Earthquake Zones
Pacific Ring of Fire
36. 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.
What instrument is used to record seismic
Explain the three types of seismic waves.
3. How is the epicenter of an earthquake
How do scientist measure the magnitude of
38. Earthquake Damage
Earthquakes are among the most powerful events
on earth, and their results can be terrifying.
• Destruction to Buildings and
Warnings and Predictions
40. Earthquake Destruction
Intensity & duration of shaking
Soil type (soft? hard rock?)
One way of
describing the size
of an earthquake is
by the amount of
shaking at some
Length of time the earthquake lasts.
45. other effects
means that the soil is turned
The liquified solid then
flows and causes severe
damage to buildings and
Water-saturated, well sorted, fine grain sands and
silts behave as fluids rather than solids.
47. other effects
a wave train, or
series of waves,
generated in a
body of water
by an impulsive
Tsunami from Chile earthquake 1960
49. Tsunami damage in Hawaii :
From 1960 Chile earthquake,
15 hours later
50. 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.
51. 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
Can opener (non-electric)
Blankets or sleeping bags
Portable radio, flashlight and spare batteries
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
Cash and change
Baby supplies: formula, bottle, pacifier, soap
and baby powder, clothing, blankets, baby
wipes, disposable diapers, canned food and
52. Stay Calm
If You Are Indoors
Protect yourself from falling debris by
standing in a doorway or crouching under a
desk or table.
53. If You Are In An Automobile
Stay away from power lines, tunnels, tall buildings,
and bridges, and stay in car until the tremors cease.
54. After an earthquake be cautious
Check for fire and fire hazards.
Watch for broken glass
Avoid downed power lines
55. Earthquake Warnings and Predictions
Earliest means of
prediction was animal
Using records of past
56. Scientists are trying to make more accurate
predictions by detecting changes in the
Faults have been located and mapped
along faults measure
small changes in rock
57. 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
58. 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
59. Tests at Rangely, Colorado
along a fault
friction and the
61. Section 6:3 Review
1. How do tall buildings usually respond during a major
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
5. What type of building construction and location
regulations should be included in the building code of
a city located near an active fault?