1. Chapter 5 Section 8 What are the different kinds of seismic waves?
Objective:
Describe three kinds of seismic waves.

2. Key Terms P-wave: fastest earthquake wave
S-wave: second earthquake wave to be recorded at a seismograph station
L-wave: surface wave

3. Primary Waves
The fastest-moving seismic waves are primary waves, or P-vases. P-waves are push- pull waves. They cause the particles in materials to move back and forth in place. The wave itself moves out from the focus. The particles move together and apart along the direction of the wave. P-waves move through solids, liquids, and gases.

4. DESCRIBE:
What are P-waves?

5. Secondary Waves
The second waves that are recorded by a seismograph is called secondary waves, or S- waves. S-waves move slower than P-waves. S- waves travel through solids only. S-waves cause the particles in materials to move from side to side. The particles move at right angles to the direction in which the waves are traveling.

6. 2. COMPARE:
Which moves faster, P-waves or S-waves?

7. Surface Waves
Surface waves are also called long waves, or L-waves. L-waves are the slowest moving waves. They are the last waves to be recorded. L-waves can travel through solids, causing Earth’s surface to rise and fall like ocean waves. They cause great damage by bending and twisting Earth’s surface.

8. 3. NAME:
What is another name for L-waves?

9. Studying Earthquake Waves
A seismogram tells scientists a great deal about earthquakes. For example, it can indicate how far away the epicenter of an earthquake is and the force of the earthquake.

10. 4. DESCRIBE:
What two things can a seismogram indicate?

11. Finding the Epicenter
To find the epicenter, seismograms from three stations are needed. Each station is at the center of the circle. The diameter of the circle is based on the travel time measured. There is only one point where all three circles cross. The epicenter is near this point.

12. Classwork CHECKING CONCEPTS There are ___ kinds of seismic waves.
The slowest-moving waves are ___.
THINKING CRITICALLY
3. DESCRIBE: Why are P-waves called push-pull waves?
4. ANALYZE: Why do you think surface waves are also called long waves?