Standard 3200-0201 Construct and defend a model of Earth's crust and interior.
Standard 3200-0202 Analyze current and past ideas about the structure of Earth.
Intended learning outcomes:
There are two classes of seismic waves: body waves, which travel at high speed through the deeper, denser rock within the body of the Earth, and surface waves, which travel at a slower speed through rock near the Earth's surface. The body waves precede the surface waves. There are two types of body waves: P-waves, which are similar to sound waves, and the slower but more damaging S-waves. P-waves travel about 4.8 to 8.0 km (3 to 5 miles) in one second, while S-waves travel about 3.2 to 4.8 km (2 to 3 miles) in one second. Surface waves are slower still and can cause even more damage due to their greater duration.
After the occurrence of an earthquake scientists observed that seismographs
on the opposite side of the earth recorded P waves but did not record
S waves. This lead them to try to discover what was inside the earth
to cause this to happen.
Use the following simulation to try to discover the internal structure of the three spheres.
Students will observe both the slow and rapid growth of iodine crystals. They will then compare their observations to the process of lava/magma cooling at different rates.
Step 1. Below you will find three spheres. Each of them has a different hidden internal structure.
Step 2. Below each sphere you are given the choices of sending different types of seismic waves through each sphere. View each simulation by dragging your mouse over the choice. Do NOT drag over the "Check your hypothesis" link until Step #4. Watch each simulation and form a hypothesis as to what the internal structure might be like. Below is the key to the colors that illustrate the waves in each simulation.
Step 3. Draw your internal structure. If you need help check out the helpful hints to find out how different waves behave in different materials.
Step 4. Test your hypothesis by checking the answers.
Step 5. Answer the questions below.
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Updated June 15, 2000 by: Glen Westbroek
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