Lab 2: The Interior of the Earth

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Lab 2 The Interior of the Earth

• Key Q What is the interior of the Earth like?

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Part A Observing Waves Measuring Wave Speed

• In our lab activity you learned that waves travel
  at a constant speed. Scientists cannot observe
  earthquake waves moving through the Earth in the
  same way you can observe waves moving through
  water. They can, however, record and study the
  energy from the earthquake waves as the waves
  arrive at a recording station (seismograph
  station). They can use
• information they
  record about
• the waves to make
  models of
• the interior of the Earth.

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Part A Observing Waves Measuring Wave Speed

• Think about how what you studied relates to how
  scientists make models of the inside of the
  Earth. What part of your experiment represented
• Th earthquake releasing energy in the Earth?
• The movement of energy waves from the earthquakes
  (seismic waves) in the Earth?
• The material in the Earth through which seismic
  waves travel?
• The arrival of a seismic wave at a seismograph
  station where earthquakes are detected?

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Part A Observing Waves Measuring Wave Speed

• Vibrations of the earths crust are earthquakes.
• When an earthquake occurs energy waves radiate
  out in all directions. These waves are called
  seismic waves.
• Scientist cannot see seismic waves traveling
  through the Earth but they can detect them with a
  seismograph.
• Seismologists, scientists that study earthquakes,
  can use the information they gather from studying
  these waves to make a conceptual model of the
  interior of the earth

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Part B Kinds of Seismic Waves

• There are 3 kinds of seismic waves. Each one
  travels at a constant speed and creates a
  different movement.
• Studying these waves can allow scientists to
• Determine the amount of energy released by an
  earthquake (magnitude)
• Determine the exact location of an earthquake
• Create a model of the interior of the Earth.

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Part B Kinds of Seismic Waves

• P-waves
• are the fastest moving waves.
• Cause particles to move back and forth in place.
• Move through solids, liquids, and gases.

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Part B Kinds of Seismic Waves

• S-waves
• Move slower than P-waves.
• Cause particles in materials to move side to
  side.
• Travel only through solids.

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Part B Kinds of Seismic Waves

• L-waves
• are the slowest moving waves.
• Cause the surface to rise and fall like ocean
  waves.
• Cause the most damage.
• Travel through solids liquids, and gases.

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Which wave

• Travel through gases?
• Travel through liquids?
• Travel through solids?
• Fastest waves?
• Surface waves?
• Slowest waves?
• Cause particles to move back forth in place?
• Cause particles to move side to side?
• Cause the most damage?
• Cause surface to rise and fall like ocean waves?

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• Seismologists scientists that study earthquakes
• Seismic waves earthquake waves
• Seismograph Instrument that detects seismic
  waves.

Fault Fracture zone where rock has been
moved Focus area along the fault where movement
first occurs Epicenter Point on the earths
surface directly above the focus.
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• Calculate the epicenter magnitude of an
  earthquake
• http//www.sciencecourseware.org/virtualearthquake
  /vquakeexecute.html

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Part C Refraction of Waves

• We learned that waves travel at a constant speed
  when they travel through one kind of material.
• A waves speed depends on what material it is
  traveling through, so when the wave (P-wave)
  crosses a boundary line between 2 different
  materials in the Earth it REFRACTS.

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Part C Refraction of Waves
REFRACTION The change in direction of a wave due
to its change in speed as it passes from one
material to the next.
P-wave
wave speed 30cm/s
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)
Boundary Line (between 2 layers of the Earth)
Greater angle 60
Angle of wave in relation to the boundary line
changed due to change in wave speed
wave speed 1m/s
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http//earthquake.usgs.gov/learn/animations/animat
ion.php?flash_titleShadowZoneflash_fileshadowz
oneflash_width220flash_height320

• Annimation from usgs kids of shadow zones ADD IT!

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Part D Refraction of Earthquake Waves in the
Earth

• P-waves
• CAN travel through the whole planet.
• Refract (change direction) at a boundary between
  the different layers of the Earth
• We know they refract because the refraction
  creates shadow zones. (an area on the Earths
  surface where no seismic waves are received.)
• S-waves
• Can NOT travel through the whole planet.
• They can travel through the Crust the Mantle
  but STOP at the Outer Core because it is liquid
  S-waves only travel through solids

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Part D Refraction of Earthquake Waves in the
Earth

• Shadow Zones
• An area on the Earths surface where no seismic
  waves are received.
• Caused by the refraction of waves.
• Shows that the earth has layers.

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Layers of the Earth
Crust cool layer of rigid rock Lithosphere
rigid layer. Includes the Crust the upper
Mantle Mantle semi-rigid layer Asthenosphere
Has plasticity (the ability to flow). lower
portion of Mantle Outer Core liquid layer. S
waves stop here. Inner Core solid