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EARTHQUAKES
& FAULTS
PREPARED BY: SARAH C.DONASCO
QUARTER 2 - WEEK 1
 Using models or illustrations,
explain how movements along faults
generate earthquakes S8ES -IIa - 14
 Differentiate the epicenter of an
earthquake from its focus; 2
intensity of an earthquake from its
magnitude; 3 active and inactive
faults S8ES -IIa - 15
How do earthquakes occur
and how are they
detected?
How can people be prepared
for earthquakes?
ACTIVE and INACTIVE FAULTS
 EARTH CRUST
The
surface/outermost
layer of the Earth
Earths Crust Two Sections
Continental Crust
Oceanic Crust
Makes up Earths landmasses
Found in the ocean floor and
usually thinner than continental
crust
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
Why are some parts of the crust
thicker than other?
How does the crust change its
shape over time?
 Some force is at work pushing and
pulling on the crust causing
changes on the surface and often
well beneath the surface
 This push-pull is called stress
 As rocks undergo stress, they slowly
change shape and volume.
What can stress do to rocks?
 A rock to become more compressed or
squeezed
 Becomes smaller in volume
 A rock to stretch out over a large area.
 The volume increases
 The rock to twist or tear apart.
 Causes the formation of fault
What can stress do to rocks?
A rock to become more
compressed or squeezed
 Becomes smaller in volume
 A rock to stretch out over a large area.
 The volume increases
 The rock to twist or tear apart.
 Causes the formation of fault
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
What is a fault?
Fracture in rocks along which
movement occured.
Some faults may cause the ground to
crack, rise or lower.
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
Two blocks of a faulted rock
Hanging Wall
 The block of rock above the fault
Foot Wall
 The block of rock below the fault
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
Kinds of fault
Normal Fault/Normal Dip-
slip Fault
 If a stress pulls the rocks apart
due to tension, the hanging wall
will move down relative to the foot
wall.
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
Kinds of fault
Reverse Dip-slip Fault/
Thrust Fault
 If stress squeezed the rocks due
to compression, the hanging wall
will move up relative to the foot
wall.
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
Kinds of Fault
Strike  slip Fault/Wrench Fault
The blocks move by sliding and
slipping along each other
horizontally but in opposite
directions.
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
Active faults
are structure where there is displacement
Usually produce a shallow earthquake
One that has moved in the past and
expected to move again.
Inactive Faults
 are structures that can be identified but
which do not cause earthquakes.
 If a fault has been inactive for million
years, it is safe to call it inactive.
PHIVOLCS
Philippine Institute of Volcanology
and Seismology
 Philippines has several fault lines
 Faults and trenches are found in the
entire country
 Trenches are the deepest part of
the oceans and are usually V-
Shaped.
Faults & Trenches
Are found close to the continents
Near strings of islands.
Near these TRENCHES:
 The crust is active causing stress and
creating faults.
About trenches
 Scientist believe that the ocean floor is
being pushed down deep into Earth along
the trenches
 When these rocks are pushed deep
enough, they are melted by the heat of
Earth.
 Some of the molten rocks will rise up
through the crust and produce volcanoes
but most of it will become part of the
Earths Mantle.
EARTHQUAKE Focus and Epicenter
Earthquake
 Shaking and trembling of earth
that results from the sudden
movement of Earths crust
Faulting
 The most common cause of
earthquake
During Faulting
 Energy is released as the rocks
break and move.
 As they move, they cause the
nearby rocks to move also.
 The rocks continue to move this
way until the energy is used up.
Tsunami
Giant ocean wave cause by Earthquake
that occur on the ocean floor.
 These waves can travel at speed of 700  800km/h.
 Can be as high as 10  20 meters (as they approach the
coast).
 The effects are devastating
 One of the worlds worst natural disaster
Focus
 The point/region where an earthquake
ruptures and the rocks break
 Underground point of origin of an
Earthquake.
 hypocenter
Epicenter
 The point on Earths surface directly
above the focus
 This where the most violent shaking
of the ground occurs.
Focal Depth
 The distance between the
focus and the epicenter
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
Earthquake Waves
 Seismic Waves
 Are the waves of energy caused by
the sudden breaking of rock within
the Earth or an explosion.
 They are the energy that travels
through Earth and is recorded on
seismographs.
Three main types of Seismic
Waves
 Primary Waves (P Waves)
 The fastest of the seismic wave
 The first to arrive at a seismic
station before any other type of
seismic wave
 Can move through the solid rocks
and fluids (like water and liquid
layers of Earth)
Three main types of Seismic
Waves
 Can move through the solid rocks
and fluids (like water and liquid
layers of Earth)
Three main types of
Seismic Waves
Secondary Wave (S Wave)
 The second wave you feel in an
earthquake
 S wave is slower than a P wave and
can only move through solid not
through liquid or gases
What happens to S
WAVES when they
reach the liquid part
of the earth?
 S waves move rock particles up
and down, or side  to  side -
perpendicular to the direction the
wave is traveling in.
Three main types of
Seismic Waves
Surface Wave (L Wave)
Travel from focus directly upward
to the epicentre.
Earths surface moves up and
down with each L wave that
passes
Cause most of the damage during
the earthquake because they
bend and twist Earths surface.
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
Seismograph
An instrument that detects and measures
waves.
Seismograms
 Seismographs record of the waves.
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
Richter Scale
 Measures how much energy an
earthquake releases by assigning
the earthquake number from 1
to 10.
 The more energy the earthquake
releases, the stronger the
earthquake is.
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
Earthquake Magnitude and
its Effects
Richter Magnitude Effects Near Epicenter
2.0 and below Generally not felt, but recorded
2.0  2.9 Potentially perceptible
3.0  3.9 Felt by some
4.0  4.9 Felt by most
5.0  5.9 Damaging Shocks
6.0  6.9 Destructive in populous regions
7.0  7.9 Major earthquake; inflict serious damage
8.0 and above Great earthquake; Destroys communities
near epicenterr
G8 Science Q2- Week1- Earthquake.pptx 2.pptx
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G8 Science Q2- Week1- Earthquake.pptx 2.pptx

  • 1. EARTHQUAKES & FAULTS PREPARED BY: SARAH C.DONASCO QUARTER 2 - WEEK 1
  • 2. Using models or illustrations, explain how movements along faults generate earthquakes S8ES -IIa - 14 Differentiate the epicenter of an earthquake from its focus; 2 intensity of an earthquake from its magnitude; 3 active and inactive faults S8ES -IIa - 15
  • 3. How do earthquakes occur and how are they detected? How can people be prepared for earthquakes?
  • 4. ACTIVE and INACTIVE FAULTS EARTH CRUST The surface/outermost layer of the Earth
  • 5. Earths Crust Two Sections Continental Crust Oceanic Crust Makes up Earths landmasses Found in the ocean floor and usually thinner than continental crust
  • 8. Why are some parts of the crust thicker than other? How does the crust change its shape over time?
  • 9. Some force is at work pushing and pulling on the crust causing changes on the surface and often well beneath the surface This push-pull is called stress As rocks undergo stress, they slowly change shape and volume.
  • 10. What can stress do to rocks? A rock to become more compressed or squeezed Becomes smaller in volume A rock to stretch out over a large area. The volume increases The rock to twist or tear apart. Causes the formation of fault
  • 11. What can stress do to rocks? A rock to become more compressed or squeezed Becomes smaller in volume A rock to stretch out over a large area. The volume increases The rock to twist or tear apart. Causes the formation of fault
  • 15. What is a fault? Fracture in rocks along which movement occured. Some faults may cause the ground to crack, rise or lower.
  • 18. Two blocks of a faulted rock Hanging Wall The block of rock above the fault Foot Wall The block of rock below the fault
  • 21. Kinds of fault Normal Fault/Normal Dip- slip Fault If a stress pulls the rocks apart due to tension, the hanging wall will move down relative to the foot wall.
  • 23. Kinds of fault Reverse Dip-slip Fault/ Thrust Fault If stress squeezed the rocks due to compression, the hanging wall will move up relative to the foot wall.
  • 25. Kinds of Fault Strike slip Fault/Wrench Fault The blocks move by sliding and slipping along each other horizontally but in opposite directions.
  • 28. Active faults are structure where there is displacement Usually produce a shallow earthquake One that has moved in the past and expected to move again.
  • 29. Inactive Faults are structures that can be identified but which do not cause earthquakes. If a fault has been inactive for million years, it is safe to call it inactive.
  • 30. PHIVOLCS Philippine Institute of Volcanology and Seismology Philippines has several fault lines Faults and trenches are found in the entire country Trenches are the deepest part of the oceans and are usually V- Shaped.
  • 31. Faults & Trenches Are found close to the continents Near strings of islands. Near these TRENCHES: The crust is active causing stress and creating faults.
  • 32. About trenches Scientist believe that the ocean floor is being pushed down deep into Earth along the trenches When these rocks are pushed deep enough, they are melted by the heat of Earth. Some of the molten rocks will rise up through the crust and produce volcanoes but most of it will become part of the Earths Mantle.
  • 33. EARTHQUAKE Focus and Epicenter Earthquake Shaking and trembling of earth that results from the sudden movement of Earths crust Faulting The most common cause of earthquake
  • 34. During Faulting Energy is released as the rocks break and move. As they move, they cause the nearby rocks to move also. The rocks continue to move this way until the energy is used up.
  • 35. Tsunami Giant ocean wave cause by Earthquake that occur on the ocean floor. These waves can travel at speed of 700 800km/h. Can be as high as 10 20 meters (as they approach the coast). The effects are devastating One of the worlds worst natural disaster
  • 36. Focus The point/region where an earthquake ruptures and the rocks break Underground point of origin of an Earthquake. hypocenter
  • 37. Epicenter The point on Earths surface directly above the focus This where the most violent shaking of the ground occurs.
  • 38. Focal Depth The distance between the focus and the epicenter
  • 40. Earthquake Waves Seismic Waves Are the waves of energy caused by the sudden breaking of rock within the Earth or an explosion. They are the energy that travels through Earth and is recorded on seismographs.
  • 41. Three main types of Seismic Waves Primary Waves (P Waves) The fastest of the seismic wave The first to arrive at a seismic station before any other type of seismic wave Can move through the solid rocks and fluids (like water and liquid layers of Earth)
  • 42. Three main types of Seismic Waves Can move through the solid rocks and fluids (like water and liquid layers of Earth)
  • 43. Three main types of Seismic Waves Secondary Wave (S Wave) The second wave you feel in an earthquake S wave is slower than a P wave and can only move through solid not through liquid or gases
  • 44. What happens to S WAVES when they reach the liquid part of the earth?
  • 45. S waves move rock particles up and down, or side to side - perpendicular to the direction the wave is traveling in.
  • 46. Three main types of Seismic Waves Surface Wave (L Wave) Travel from focus directly upward to the epicentre. Earths surface moves up and down with each L wave that passes Cause most of the damage during the earthquake because they bend and twist Earths surface.
  • 50. Seismograph An instrument that detects and measures waves. Seismograms Seismographs record of the waves.
  • 54. Richter Scale Measures how much energy an earthquake releases by assigning the earthquake number from 1 to 10. The more energy the earthquake releases, the stronger the earthquake is.
  • 56. Earthquake Magnitude and its Effects Richter Magnitude Effects Near Epicenter 2.0 and below Generally not felt, but recorded 2.0 2.9 Potentially perceptible 3.0 3.9 Felt by some 4.0 4.9 Felt by most 5.0 5.9 Damaging Shocks 6.0 6.9 Destructive in populous regions 7.0 7.9 Major earthquake; inflict serious damage 8.0 and above Great earthquake; Destroys communities near epicenterr