1. Earthquakes
Chapter Notes

2. What do you know about earthquakes?
What causes them?
Are they destructive?
Can we stop them from occurring?
Who do they affect?

3. What is an earthquake?
An earthquake is a shaking & trembling that results from the movement of rock beneath Earth’s surface.
Most earthquakes are too small to notice.
80% of all earthquakes occur around the edges of the Pacific Ocean.

4. Plate movement causes stress.
The energy released by an earthquake travels as seismic waves, which are vibrations that travel through the Earth.
Focus is the area beneath Earth’s surface where rock under stress begins to move.
Epicenter is the point on the Earth’s surface directly above the epicenter.

5. Diagram Of Focus & Epicenter

6. Types of Seismic Waves Primary Waves (P Waves)
Compress & expand the ground
Fastest; first to reach any location
Secondary Waves (S Waves)
Vibrate side to side
Second to reach any location
Surface Waves
Slowest
Travel along the surface
Circular/rolling motion

7. Primary Waves (P Waves)

8. Secondary Waves (S Waves)

9. How are earthquakes measured?
A seismograph is an instrument that constantly records ground movement.

10. Typical Seismogram Reading

11. How are Earthquakes Measured? Mercalli Scale
Click Link for Interactive Demo

12. How are Earthquakes Measured? Richter Scale

13. Earthquake Damage

14. Earthquake Summary

15. Tsunamis

16. What is a tsunami?
A tsunami is a water wave triggered by an earthquake, volcanic eruption or landslide.

17. Does Oklahoma Have Earthquakes?
Oklahoma does have earthquakes they are usually of a lower magnitude.
Question
When was the last earthquake recorded in Oklahoma?
Let’s see if you’re correct!

18. REVIEW What is an earthquake? What are types of seismic waves?
What are the 2 parts of an earthquake?

19. Ticket Out The Door
Answer the following question in 3-4 complete sentences: In what ways do earthquakes and tsunamis impact or affect the world?