1. Ch. 8 Types of Stress that cause Earthquakes

2. What does the elastic rebound theory describe. A
What does the elastic rebound theory describe? A. the build-up and release of stress during an earthquake B. the fluctuations in groundwater prior to an earthquake C. the formation of mountain ranges by successive earthquakes D. the strength of an earthquake
Which of the following types of seismic waves arrive at a seismograph first? A. P waves B. S waves C. surface waves D. All of these waves arrive at the same time.
Who developed the procedure used to measure the size of an earthquake? A. Charles Richter B. James Hutton C. Charles Darwin D. Harry Hess
How many seismograph stations are needed to locate the epicenter of an earthquake? A. 1 B. 2 C. 3 D. 4 or more
Earthquakes that originate at depths greater than 100 km are associated with ______ plate boundaries. A. convergent B. divergent C. transform D. convergent, divergent, and transform
Which of the following observations may indicate a forthcoming destructive earthquake? A. an increase in the frequency of smaller earthquakes in the region B. rapid tilting of the ground C. rapid changes in water levels in wells D. all of these

3. What does the elastic rebound theory describe. A
What does the elastic rebound theory describe? A. the build-up and release of stress during an earthquake B. the fluctuations in groundwater prior to an earthquake C. the formation of mountain ranges by successive earthquakes D. the strength of an earthquake
Which of the following types of seismic waves arrive at a seismograph first? A. P waves B. S waves C. surface waves D. All of these waves arrive at the same time.
Who developed the procedure used to measure the size of an earthquake? A. Charles Richter B. James Hutton C. Charles Darwin D. Harry Hess
How many seismograph stations are needed to locate the epicenter of an earthquake? A. 1 B. 2 C. 3 D. 4 or more
Earthquakes that originate at depths greater than 100 km are associated with ______ plate boundaries. A. convergent B. divergent C. transform D. convergent, divergent, and transform
Which of the following observations may indicate a forthcoming destructive earthquake? A. an increase in the frequency of smaller earthquakes in the region B. rapid tilting of the ground C. rapid changes in water levels in wells D. all of these

4. What is an Earthquake?
Earthquake - the vibrations produced when a rock snaps and breaks under different types of stress.

5. The Elastic Rebound Theory
Rocks will bend until they reach their Elastic Limit.
Then they will break (crack)
Forming a Fault

6. How do Earthquakes Occur?
Rocks on a fault are jagged & get stuck when plates move.
Stress Builds
Rocks bend until they can’t & then snap back to their original position. (Elastic Rebound Theory)

7. Parts of a Fault

8. 1. Normal Fault

9. Normal Fault Rocks/plates are pulled apart (tension stress)
Tension causes the hanging wall to fall down.
(Divergent Boundary)

10. Normal Fault

11. Normal Fault

12. Normal Fault

13. Reverse Fault

14. Reverse Fault Rocks/plates are pushed together. (compression stress)
Causes the Hanging wall to move up.
Earthquakes!!!!
(Convergent Boundary)

15. Reverse Fault

16. Reverse Fault

17. Thrust fault = special Reverse Fault!
Angle of fault plane is shallow.

18. Strike Slip Fault
Rock/plates are sliding in opposite directions. (shearing stress)
Movement is only horizontal.
EARTHQUAKES!!!
(Transform Boundary)

19. Strike-Slip Fault (Transform)

20. Strike – Slip Fault

21. Strike-Slip Fault (Right Lateral)

22. Strike Slip Fault

23. Oblique-Slip Fault Horizontal and Vertical Movement
Caused by Tensional and Shear Stress.