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Earthquakes

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1Earthquakes and Plate Tectonics
2Types of Seismic Waves
Recording Earthquakes
Measuring Earthquakes...
1
Earthquakes are vibrations in the earth’s
crust

The movement between plate and along faults is not smooth
They move in je...
Stress and Strain
• stress – total force
acting on crustal
rocks per unit area
• strain – deformation
of materials in
resp...
Earthquake Vocab
• Focus
• Epicenter
• Fault
Focus – Area where slippage first occurs
Earthquakes create seismic waves which shake the ground
as they pass. Earthquakes create waves just like waves of
water mo...
Consider what happens when a drop of rain hits a pond of water.
The drop disturbs the flat surface of the water and create...
FAULTS
Distant forces cause a
gradual build up of stress
in the earth over tens or
hundreds or thousands of
years, slowly ...
Stresses
Connection to Plate Tectonics
• What type of boundary causes tension?
• divergent
• What type of boundary causes
compressi...
Mid-Ocean Ridges

This is a map of the major oceanic spreading centers.
Types of Faults
Reverse (convergent)
• Compression causes
horizontal and vertical
movement
• Where might this occur
(real-...
Types of Faults
Strike-slip (transform)
• Shear causes horizontal
movement
• Where might this occur
(real-world example)?
Fault Zones

Faults are narrow zones in
the Earth, usually extending
no more than about 10
miles deep, which separate
rigi...
California Faults

• http://www.pbslearningmedia.org/resource/ess
The Pacific plate
is moving to the
northwest at a
rate of about 4
inches per year.
2
• Types of Seismic Waves
• Recording Earthquakes
• Locating Earthquakes
Types of Seismic Waves
Earthquakes generate three major types of
seismic waves
P, for "Primary"
S, for "Secondary" waves
L...
P Waves - Primary
Move the fastest and are the first recorded by a
seismographic
Can travel through liquids and solids

Th...
S Waves - Secondary
Secondary Waves are the second to be
recorded by a seismograph,
Can only travel through solid material...
L Waves – Long Waves or Surface
Waves

Surface or L waves occur only in the earth's crust
and cause the most damage
travel...
Recording Earthquakes

An earthquake is a sudden shaking of the ground. They
generate seismic waves which can be recorded ...
Advances in
seismograph
technology have
increased our
understanding of
both earthquakes
and the Earth
itself.
Perhaps the earliest seismograph was invented in China A.D.
136 by a man named Choko.
The Seismograph

• http://www.pbslearningmedia.org/resource/ess
Earthquake Measurement

Richter Scale expresses
the magnitude or measure
of energy released by an
earthquake.

Mercalli sc...
I. Instrumental
II. Feeble
III. Slight
IV. Moderate
V. Rather strong
VI. Strong
VII. Very strong
VIII. Destructive
IX. Rui...
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...
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...
Locating an Earthquake

The point beneath the Earth's surface where the rocks
break and move is called the focus. The focu...
Epicenter

Focus
Scientist must
have information
from three
seismographic
stations at
different
locations to plot
the epicenter of
an earth...
Need readings
from three
seismic
centers to
locate
epicenter. The
epicenter is
the point at
which the
circles
intersect.
Three Major Earthquake Zones

Pacific Ring of Fire
New Madrid Earthquake
December of 1811, the largest earthquake ever recorded in American
History started. This earthquake,...
Review
1.

What instrument is used to record seismic
waves?

2.

Explain the three types of seismic waves.

3. How is the ...
Earthquake Damage
Earthquakes are among the most powerful events
on earth, and their results can be terrifying.
3
• Destruction to Buildings and
Properties
Tsunamis
Earthquake Safety
Earthquake
Warnings and Predictions
Earthquake Destruction
important factors:

Intensity & duration of shaking
Soil type (soft? hard rock?)
Building design
1964 Valdez, Alaska

• http://www.pbslearningmedia.org/resource/ean
Tsunami damage:
Alaska 1964 earthquake
Intensity
One way of
describing the size
of an earthquake is
by the amount of
shaking at some
particular location.
Duration

Length of time the earthquake lasts.
other effects
Liquifaction
Liquefaction essentially
means that the soil is turned
into liquid.
The liquified solid then
fl...
Liquifaction

Water-saturated, well sorted, fine grain sands and
silts behave as fluids rather than solids.
other effects
A tsunami
(pronounced
tsoo-nah-mee) is
a wave train, or
series of waves,
generated in a
body of water
by an ...
Tsunami
is a
Big Wave

Tsunami from Chile earthquake 1960
Magnitude 9.5
Tsunami damage in Hawaii :
From 1960 Chile earthquake,
15 hours later
Earthquake Safety

Stocking up now on emergency
supplies can add to your safety and
comfort during and after an
earthquake...
Water: 1 gallon per person per day (a week's
supply of water is preferable)
Water purification kit
First aid kit, freshly ...
Stay Calm

If You Are Indoors

Protect yourself from falling debris by
standing in a doorway or crouching under a
desk or ...
If You Are In An Automobile
Stay away from power lines, tunnels, tall buildings,
and bridges, and stay in car until the tr...
After an earthquake be cautious
Check for fire and fire hazards.
Watch for broken glass
Avoid downed power lines
Earthquake Warnings and Predictions
Earliest means of
prediction was animal
behavior

Using records of past
earthquakes
Scientists are trying to make more accurate
predictions by detecting changes in the
earth’s crust.
Faults have been locate...
Seismic Gaps – Zones of immobile
rock along faults
Scientists think that
seismic gaps, where the
fault is locked and
unabl...
Other Warnings
Slight tilting of the ground
Detect strain and cracks caused by stress
Change in magnetic and electrical
pr...
Tests at Rangely, Colorado
Injected water
along a fault
which reduced
friction and the
earthquakes
were less
severe
Forecasting EQ’s

• http://www.pbslearningmedia.org/resource/nvs
Section 6:3 Review
1. How do tall buildings usually respond during a major
earthquake?
2. What causes tsunamis?
3. What sh...
Earthquakes
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Earthquakes

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HS Earth Science - Earthquakes Unit

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  • 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
  • Transcript of "Earthquakes"

    1. 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. 2. 1
    3. 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. 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. 5. Earthquake Vocab • Focus • Epicenter • Fault
    6. 6. Focus – Area where slippage first occurs
    7. 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. 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.
    9. 9. 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
    10. 10. Stresses
    11. 11. 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
    12. 12. Mid-Ocean Ridges This is a map of the major oceanic spreading centers.
    13. 13. 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)?
    14. 14. Types of Faults Strike-slip (transform) • Shear causes horizontal movement • Where might this occur (real-world example)?
    15. 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 plate.
    16. 16. California Faults • http://www.pbslearningmedia.org/resource/ess
    17. 17. The Pacific plate is moving to the northwest at a rate of about 4 inches per year.
    18. 18. 2 • Types of Seismic Waves • Recording Earthquakes • Locating Earthquakes
    19. 19. Types of Seismic Waves Earthquakes generate three major types of seismic waves P, for "Primary" S, for "Secondary" waves L, for “Long” waves
    20. 20. 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
    21. 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. 22. 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.
    23. 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. 24. Advances in seismograph technology have increased our understanding of both earthquakes and the Earth itself.
    25. 25. Perhaps the earliest seismograph was invented in China A.D. 136 by a man named Choko.
    26. 26. The Seismograph • http://www.pbslearningmedia.org/resource/ess
    27. 27. 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.
    28. 28. 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
    29. 29. 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
    30. 30. 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
    31. 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.
    32. 32. Epicenter Focus
    33. 33. Scientist must have information from three seismographic stations at different locations to plot the epicenter of an earthquake
    34. 34. Need readings from three seismic centers to locate epicenter. The epicenter is the point at which the circles intersect.
    35. 35. Three Major Earthquake Zones Pacific Ring of Fire
    36. 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.
    37. 37. 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?
    38. 38. Earthquake Damage Earthquakes are among the most powerful events on earth, and their results can be terrifying.
    39. 39. 3 • Destruction to Buildings and Properties Tsunamis Earthquake Safety Earthquake Warnings and Predictions
    40. 40. Earthquake Destruction important factors: Intensity & duration of shaking Soil type (soft? hard rock?) Building design
    41. 41. 1964 Valdez, Alaska • http://www.pbslearningmedia.org/resource/ean
    42. 42. Tsunami damage: Alaska 1964 earthquake
    43. 43. Intensity One way of describing the size of an earthquake is by the amount of shaking at some particular location.
    44. 44. Duration Length of time the earthquake lasts.
    45. 45. 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
    46. 46. Liquifaction Water-saturated, well sorted, fine grain sands and silts behave as fluids rather than solids.
    47. 47. 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
    48. 48. Tsunami is a Big Wave Tsunami from Chile earthquake 1960 Magnitude 9.5
    49. 49. Tsunami damage in Hawaii : From 1960 Chile earthquake, 15 hours later
    50. 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. 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 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.
    52. 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. 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. 54. After an earthquake be cautious Check for fire and fire hazards. Watch for broken glass Avoid downed power lines
    55. 55. Earthquake Warnings and Predictions Earliest means of prediction was animal behavior Using records of past earthquakes
    56. 56. 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.
    57. 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 earthquakes
    58. 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. 59. Tests at Rangely, Colorado Injected water along a fault which reduced friction and the earthquakes were less severe
    60. 60. Forecasting EQ’s • http://www.pbslearningmedia.org/resource/nvs
    61. 61. 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?
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