Earth From Core to Crust

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Earth From Core to Crust

• The Answers to the Questions
• (Who said I never dun nuthin for ya?)

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Put on a happy face!
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• What is the purpose of seismology?
• Learn about the internal structure of the earth
• Useful for science but also in mineral industry
  oil and gas especially

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2. What does a seismograph read? Search the
internet for an image of a seismograph and copy
it into your notes. Be sure to reference it
properly.
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http//www.spiegel.de/img/0,1020,422036,00.jpg
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http//www.seismo.unr.edu/ftp/pub/louie/class/100/
seismograph.GIF
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Seismographs are the principal tool of scientists
who study earthquakes. Thousands of seismograph
stations throughout the world. Fundamentally, a
seismograph is a simple pendulum. When the ground
shakes, the base and frame of the instrument move
with it, but inertia keeps the pendulum bob in
place. It will then appear to move, relative to
the shaking ground. As it moves it records the
pendulum displacements as they change with time,
tracing out a record called a seismogram.
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http//www.noaanews.noaa.gov/stories2005/images/se
ismograph-globalnetwork.jpg
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• 3. What are the two broad categories of shock
  waves?
• surface waves that travel only along the surface
  of Earth
• waves that go through the earth

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• 4. What are the two types of waves that pass
  through the earth? Briefly describe them.
• P waves primary waves - pass through any
  material
• S waves secondary waves pass only through
  solid (bounce off liquid)

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5. What happens to the P waves and the S waves at
approximately 2900km depth? Why? What is this
layer called? P waves slow down S waves
stop called Gutenberg Discontinuity at the depth
of the outer core (which is liquid)
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6. Is the core homogeneous? Describe it
briefly. not homogeneous outer part liquid and
an inner part solid outer part liquid because of
incredible heat inner part solid because of
incredible pressures one third of mass of
earth heaviest, densest elements pulled to centre
of earth when earth was cooling
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http//www.oup.co.uk/images/oxed/children/yoes/ear
th/earthcore.jpg
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7. What accounts for the very high temperatures
in the core? Inner core is hot due to
radioactive decay
8. Copy Figure 2.6, page 21, into your notes.
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9. What does the outer core create? (See page
22.) Fluid outer core creates earths magnetic
field
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10. Where is the mantle? Between the core and
the crust
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11. Where is the asthenosphere? How does the
asthenosphere differ from the rest of the mantle?
What does this difference account for? Upper
part of the mantle Convection currents in the
asthenosphere cause plate tectonics
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12. From the "Career Planet" box on page 23 What
does a seismologist do? Oil and gas
prospecting Monitoring tectonic activity (earth
movement earthquakes and volcanic
eruptions) Highly trained degree in geology,
engineering physics with post graduate
training/degrees