Your tream is lead by Dr. Seismos of the University of Athens

No one can really take a journey to the center of the Earth, but for centuries people have imagined what the interior of the earth is like.

Since seismic waves resulting from Earthquakes travel through the entire earth, scientists have studied these waves to get a picture of the structure and composition of the Earth's interior.

Both S-waves and P-waves travel faster through hard material than through soft material.  Therefore, the speed of these waves through a part of the Earth indicates the hardness of the rock found thre.  The speed and direction of these waves change as the waves pass through the Earth. 

• P-waves slow down as they pass through liquids.
• S-waves stop when they strike a liquid.

 The diagrams on this page and the back of this sheet were created by your research team, based on earthquake data you collected.  Study these diagrams and answer the questions below:

1. Which type of wave moves fastest? _________________

2. As the waves move from the crust inward, at what point do they change speed abruptly?

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3. What does the abrupt change in wave speed indicate about the material the waves are striking at that point?

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4. What structural change does the change in wave speed indicate?

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