1. Chapter 12 Section 2 Earthquakes

2. Chapter 12 Section 2 – What You’ll Learn - page 363 Before you read - write the reading’s objectives in this space: 1 – _____________________________________________________________________________________________ 2 – _____________________________________________ ________________________________________________ ________________________________________________ ________________________________________________ 3- ______________________________________________ ________________________________________________ ________________________________________________ _________________________________________

3. Chapter 12 Section 2 – What You’ll Learn - page 363 Before you read - write the reading’s objectives in this space: 1 – Describe the causes and characteristics of earthquakes. 2 – Explain how seismic waves affect Earth’s surface. 3- Describe how seismic waves are used to infer Earth’s internal structure.

4. Define earthquake: ______________________________ ____________________________________________ Globally, how are most earthquakes distributed? _____________________________________________________ 1

5. Define earthquake: An earthquake is any seismic vibration of Earth caused by the rapid release of energy. Globally, how are most earthquakes distributed? The zones coincide with the edges of lithospheric plates. 1

6. Define focus (As pertaining to earthquakes):____________ ____________________________________________ What kind of foci do divergent boundaries have? _______________________________________ What kind of foci do convergent boundaries have? ___________________________________________________________________________________ 2

7. Define focus (As pertaining to earthquakes): The point of origin of an earthquake. What kind of foci do divergent boundaries have? Narrow bands of numerous shallow earthquakes What kind of foci do convergent boundaries have? Broad zones with the shallowest focal points are near the surface where boundaries converge. The deepest focal points lie under mountains or volcanoes that are created by the collisions. 2

8. Explain deformation in reference to earthquakes: __________________________________________ _________________________________________ _________________________________________ _________________________________________ Name and define the four types of stress: 1._________________________________________ 2._________________________________________ 3._________________________________________ _________________________________________ 4._________________________________________ 3

9. Explain deformation in reference to earthquakes: Stress is the force per unit area that acts on a material. As plates shift a stress or strain is placed on the plate. Brittle, ridged rocky material shows very little sign of deformation but then will suddenly break. Name and define the four types of stress: 1.Compressive – material is squeezed or shortened 2.Tensional – material is stretched or lengthened 3.Shear – material is moved in opposite directions along a plane 4.Torsion – material is twisted 3

10. Save for class work - Four Types of Stress Mini-Lab Answers: 1. With palms facing down at all times and your hands in contact with each other, clasp a large bar of taffy with both hands. First, push one hand forward 2 cm while simultaneously pulling the other backward 2 cm. Return your hands to the original position. Type of stress - ______________________________________________ Kind of deformation - __________________________________________ 2. Still holding your hands in contact, twist your hands in opposite directions and return them to the original position. Type of stress - _______________________________________________ Kind of deformation - __________________________________________ 3. Next move your hands about 4 cm apart. Type of stress - _______________________________________________ Kind of deformation - __________________________________________ 4. Finally push your hands back together to the original position. Type of stress - _______________________________________________ Kind of deformation - __________________________________________ 4

11. Four Types of Stress Mini-Lab Answers: 1. With palms facing down at all times and your hands in contact with each other, clasp a large bar of taffy with both hands. First, push one hand forward 2 cm while simultaneously pulling the other backward 2 cm. Return your hands to the original position. Type of stress - shear Kind of deformation – shaved off, split, sliced, ground up, scraped, peeled, abrasion 2. Still holding your hands in contact, twist your hands in opposite directions and return them to the original position. Type of stress - torsion Kind of deformation – twisted, wrenched, wound-up, coiled, curled 3. Next move your hands about 4 cm apart. Type of stress - tension Kind of deformation – stretched, pulled apart, broken, pulled thin 4. Finally push your hands back together to the original position. Type of stress - compression Kind of deformation – smooshed, squeezed, folded, compressed, crushed 4

14. Define elastic deformation:______ _________________________ _________________________ _________________________ _________________________ _________________________ Define plastic deformation:______ _________________________ _________________________ _________________________ 5

15. Define elastic deformation: Elastic deformation occurs when a material deforms as a stress is applied, but returns to its original shape when the stress is removed. Define plastic deformation: Plastic deformation occurs when a material deforms, or changes shape, as a stress is applied and remains in the new shape when the stress is released. 5

16. Energy Release: When this strain energy is released suddenly, it causes rock to lurch to a new position. Define fault: ____________________________ The sudden energy release that goes with fault movement is called _____ ___________________ 6

17. Energy Release: When this strain energy is released suddenly, it causes rock to lurch to a new position. Define fault: A crack along which movement has taken place. The sudden energy release that goes with fault movement is called elastic rebound. 6

18. Recall an earthquakes focus: _______________________ _______________________ _______________________ What is an earthquake’s epicenter? _______________ _______________________ _______________________ _______________________ 7

19. Recall an earthquakes focus: The point of origin of an earthquake. What is an earthquake’s epicenter? The point on Earth’s surface directly above the focus 7

20. What are Primary waves (P-waves)? ____________________________________________________________ Recall in the waves section that if you attach the tie to one on the rungs the particles do not change location. P-waves travel through all kinds of matter. 8

21. What are Primary waves (P-waves)? P-waves are compressional waves. This causes particles in a material to undergo a push-pull type motion. Recall in the waves section that if you attach the tie to one on the rungs the particles do not change location. P-waves travel through all kinds of matter. 8

22. What are secondary waves (s-waves or shear waves)? ___ _________________________________________ _________________________________________ _________________________________________ Remember: Transverse waves cause particles to move perpendicular to the direction of wave travel. S-waves can only travel through solids. 9

23. What are secondary waves (s-waves or shear waves)? Are transverse waves, sometimes called shear waves, because of the relative motion of particles as energy is transferred. Remember: Transverse waves cause particles to move perpendicular to the direction of wave travel. S-waves can only travel through solids. 9

24. Surface waves move in a more complex manner. They can exhibit an up and down rolling motion, and also a side-to-side motion that parallels Earth’s surface. 10

26. Earthquake Measurement The Modified Mercalli scale ranks earthquakes in a range from I-XII, XII being the worst and uses eyewitness observation and post- earthquake assessments to assign an intensity value.

27. Earthquake Measurement Richter magnitude is intended to give a measure of the energy released during the earthquake. The Richter magnitude scale uses the amplitude of the largest earthquake wave. EQ as seen by a surveillance camera Click here

28. What increases earthquake damage and loss of life?________________________________________ Earthquake Proofing -Although no building can be made entirely earthquake proof, scientists and engineers are finding ways to reduce the damage to structures during mild or moderate earthquakes. 11

29. What increases earthquake damage and loss of life? Research has shown that poor building methods are the largest contributors to earthquake damage and loss of life. Earthquake Proofing -Although no building can be made entirely earthquake proof, scientists and engineers are finding ways to reduce the damage to structures during mild or moderate earthquakes. 11

30. Question 1 Which of the following is NOT a type of stress in rock? A. compression B. epicenter C. shearing D. tension Section Check 12

31. Question 1 Which of the following is NOT a type of stress in rock? A. compression B. epicenter C. shearing D. tension Section Check Answer The answer is B. The epicenter is the point on Earth’s surface located directly above the earthquake’s center. 12

32. Question 2 Where do P- and S-waves occur in relation to surface waves? Section Check 13

33. 2 2 Question 2 Where do P- and S-waves occur in relation to surface waves? Answer Seismic waves travel away from the epicenter in all directions. P-waves travel the fastest through rock material. S-waves move through the rock and cause particles to vibrate. Both P- and S- waves travel through the Earth’s interior while surface waves move along Earth’s surface. Section Check 13

34. Question 3 Why is it difficult to predict earthquakes? Section Check 14

35. Question 3 Why is it difficult to predict earthquakes? Section Check Answer Geologists can monitor changes in Earth that are associated with earthquakes. Measuring devices have been developed to assess changes in groundwater level and rock layers; however, no single change in Earth occurs for all earthquakes. 14