Shadow Zone Rollover Open

Novice

 Can you show me the different shadow zones alone and at once?

This rollover shows the different P and S phases and their respective shadow zones.

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Keypoints:

This rollover shows the different P and S phases and their respective shadow zones.

  • P waves are compressive and can pass through liquids
  • The P-wave shadow zone is caused by refraction in the Earth
  • S waves cannot propagate through liquids
  • The S-wave shadow zone is all points beyond 104°

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Seismic shadow zones have taught us much about the inside of the earth. This shows how P waves travel through solids and liquids, but S waves are stopped by the liquid outer core.

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The shadow zone is the area of the earth from angular distances of 104 to 140 degrees from a given earthquake that does not receive any direct P waves. The different phases show how the initial P wave changes when encountering boundaries in the Earth.

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The shadow zone results from S waves being stopped entirely by the liquid core. Three different S-wave phases show how the initial S wave is stopped (damped), or how it changes when encountering boundaries in the Earth. 

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Seismic waves travel a curving path through the earth due to changes in composition, pressure, and temperature within the layers of the Earth. 

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Related Lessons

Learning occurs as students work first in small groups and then as a whole class to compare predicted seismic wave travel times, generated by students from a scaled Earth model, to observed seismic data from a recent earthquakes. This activity uses models, real data and emphasizes the process of science.

Lesson Novice