Seismic Waves Webquest 1. A seismic wave is a wave that travels through the Earth. It transfers energy from one spot to another within the earth. 2. Earthquakes cause seismic waves. 3. Earthquakes occur because energy that has been stored up for long periods of time is suddenly released. 4. This energy is the result of movements of large pieces of Earth’s crust that pull and push against each other (called plate tectonics). Seismologists recognize different types of waves but we are interested in only two types: P (primary) waves, which are longitudinal (similar to sound waves), and can travel through solids and liquids S (secondary) waves, which are transverse waves and can only travel through solids. Pre-­‐Activity Questions Try to answer the following questions: 1. S-­‐waves cannot travel through liquids because … 2. P-­‐waves travel faster than s-­‐waves because … 3. Seismologists can tell how far away an earthquake is by… 4. When a wave hits a new medium it… 5. Scientists have determined what the interior of the Earth may look like by… Procedures: 1. Go to http://aspire.cosmic-­‐ray.org/Labs/SeismicWaves/ you can also access this website in the resources section of this lesson. 2. Spend 1-­‐2 minutes playing with the Mighty Wave Maker and answer the questions online. 3. Go back and check your answers to the Pre-­‐Activity Questions above. Using the website, correct your answers if needed. At the bottom of the page click on “Discover More about the Earth’s Interior.” And follow the instructions on the next page. 4. Follow the instructions on the website as you move through the next three slides. When you get to the fourth slide, draw a picture of Earth’s Interior below: 5. Still on slide four, left click on one of the houses. On your diagram, draw where the P and S waves travel. (Use different colors for clarity and keep your drawing neat.) 6. According to calculations, what have scientists predicted Earth’s core is composed of? 7. Why do scientists think the center of the core is solid? 8. What 3 things increase as you get closer to the center of the Earth? 9. On your diagram, label the relative densities of the layers of the Earth. (use a different color for clarity.) 10. Scientists have determined that the mantle is ___________________. Why have scientists given it this name? 1.
Graphics obtained 8/1/09 by AMHoyle from http://www.seismo.unr.edu/ftp/pub/louie/class/100/seismic-­‐
waves.html 2.
Adapted from http://aspire.cosmic-­‐ray.org/labs/seismic/index.htm, obtained 8/1/09by AMhoyle