Seismic waves are vibrations that transport energy through the Earth, originating from a focus where rock breaks, leading to an earthquake. The epicenter is the point on the surface directly above the focus, and there are three main types of seismic waves: P waves (primary waves), S waves (secondary waves), and surface waves. A seismograph is used to record the ground movement caused by these seismic waves.

2. Seismic waves-
vibrations that travel
through Earth
carrying energy

3. Focus- point beneath
Earth’s crust where rock
breaks, triggering an
earthquake
Epicenter- point on
surface directly above
the focus

4. Fault
Fault
Focus
Epicenter

5. Types of Seismic Waves
• P waves
• S waves
• Surface waves

6. 1. P wave- primary
wave, waves that
compress and expand
Types of waves
http://www.pbs.org/wnet/savageearth/earthquakes/index.html

7. 2. S wave- secondary
wave, waves that vibrate
up and down as well as
side to side
Types of waves
http://www.pbs.org/wnet/savageearth/earthquakes/index.html

8. 3. Surface wave- waves
that make the ground
shake
Types of waves
http://www.pbs.org/wnet/savageearth/earthquakes/index.html

9. Seismograph-
records ground
movement caused by
seismic waves

10. http://www.nationalgeographic.com/forcesofnature/
interactive/index.html?section=e