Modified True/False - Indicate Whether the Statement Is True Or False

Chapter 19 – Earthquakes Study Guide

Modified True/False - Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true. ____ 1. On a seismometer, the suspended mass tends to stay at rest during an earthquake because of inertia. ____ 2. If two seismic stations receive data from an earthquake, the quake’s location can be computed if P- waves, S-waves, and surface waves have been received. ____ 3. The Richter Scale measures intensity, or the damaged caused by an earthquake. ____ 4. Seismic belts are relatively narrow and tend to follow tectonic plate boundaries. ____ 5. A stress line is a fracture in rock along which movement occurs ____ 6. S-waves are refracted, or bent, by Earth’s outer core. ______7. The fact that a significant earthquake has not occurred within a seismic gap indicates that an earthquake is more likely to occur in the near future. ____ 8. Stress is the forces per unit area acting on crustal rocks that can lead to earthquakes ____ 9. The amount of damage done to structures as a result of an earthquake is the earthquake’s magnitude. ______10. A tsunami is a wave generated by vertical motions of the seafloor

Multiple Choice - Identify the choice that best completes the statement or answers the question.

____ 11. The focus is the point where ______a. the waves originate. c. the waves are attracted. b. the surface waves originate and spread out. d. the most surface damage will occur.

____ 12. Which type of material would be best to use for construction in an area prone to earthquakes? a. Concrete c. Brick b. Wood d. Stone

____ 13. The strain which causes a material to pull apart is known as ____. a. tension c. stress b. compression d. shear

____ 14. Movement occurs along fractures in rocks when stress _____ the rocks involved. a. equals the strength of c. is applies to b. overcomes the strength of d. is less than Chapter 19 – Earthquakes Study Guide

Use the diagram to answer the questions. ____ 15. Which point marks the epicenter of the earthquake? a. C c. A b. D d. B

____ 16. At which point will the most damage as a result of the earthquake occur? a. A c. C b. D d. B

Use the diagram to answer the questions. ____ 17. What keeps the stable part of this seismometer from moving during an earthquake? a. its location c. its mass b. gravity d. inertia

____ 18. Which part of the seismometer does not shake during an earthquake? a. the mass c. the rotating drum b. the spring d. the frame

____ 19. The stress which causes a material to twist is known as ____. a. Tension c. Strain b. compression d. Shear Chapter 19 – Earthquakes Study Guide

Use the graph to answer the questions 19-20. ____ 21. A seismogram is located 4500 miles away from the epicenter of an earthquake. What is the difference in time between when the P-waves reach the seismogram and the S-waves reach the seismogram? a. 5 1/2 minutes c. 6 minutes b. 10 minutes d. 22 minutes

____ 22. P-waves reaches a seismogram 6 minutes after an earthquake occurs and the S-waves arrive 3 and a half minutes later. How far is the seismogram from the earthquakes epicenter? a. 2000 km c. 3000 km b. 1000 km d. 4000 km

Location Earthquake Strain Buildup History Rate A many earthquakes slow B few earthquakes moderate C many earthquakes fast D many earthquakes moderate ____ 23. Using the chart above, Organize the locations from lowest to highest hazard. a. B, A, D, C c. C, D, A, B b. A, B, C, D d. B, A, C, D

____ 24. Using the chart above, Location D just experienced an earthquake. Which location will most likely experience the next earthquake? a. Location C because it has the highest c. It is impossible to tell because the hazard. proximity of the other locations to D is not known. b. Location A because it is just below d. It is impossible to tell because the data location D in hazard level. just gives the risks for earthquakes not a predictable forecast.

____ 25. A ____ fault forms as a result of horizontal compression. a. blind c. strike-slip b. reverse d. normal Chapter 19 – Earthquakes Study Guide

____ 26. Deaths associated with earthquake deaths in sloping areas can result from ____. a. tsunamis c. formation of fault scarps b. surface ruptures d. landslides

____ 27. Measure of the energy released by a quake a. magnitude c. stress b. intensity d. strain

____ 28. A numerical scale of earthquake magnitude that takes into account the size of the fault rupture is the ____. a. moment magnitude scale c. Richter scale b. modified Mercalli scale d. epicentral distance scale

____ 29. The San Andreas Fault, a result of horizontal shear, is a ____ fault. a. blind c. reverse b. normal d. strike-slip

____ 30. Section of an active fault that has not experienced a significant earthquake for a long time a. epicenters c. strain b. seismic gaps d. seismic belts

____ 31. The locations of seismic belts are determined by plotting ____. a. earthquake foci c. earthquake epicenters b. seismic gaps d. epicentral distances

Matching - Match each item with the correct description below. You may use a term more than once. a. surface wave b. P-wave c. S-wave ____ 32. Is refracted by Earth’s core ____ 33. Absence of this kind of waves results in a shadow zone ____ 34. Squeezes and pulls rocks in same direction as the wave travels ____ 35. Does not pass through Earth’s liquid outer core ____ 36. Does not pass through Earth’s interior at all

Completion - Complete each statement using the bold words fault plane normal fault reverse fault strike-slip fault 37. Along a(n) ______, movement is both horizontal and vertical, resulting in a lengthening of the crust involved. 38. A(n) ______forms as a result of horizontal compression and results in a shortening of the crust involved. 39. In a(n) ______, the fracture is caused by horizontal shear and movement is mainly horizontal. 40. The surface along which fault movement takes places is the ______. Chapter 19 – Earthquakes Study Guide

Open Response Question

Use the diagram to answer the questions.

41. A. The three seismograms all detected P-waves and S-waves at different times. According to the information, what point is the epicenter of the earth quake? Explain.

B. Suppose station #2 did not detect any P-waves or S-waves. Could the information from station #1 and station #3 still be used to determine the location of the epicenter?

C. How has the P-waves and S-waves of an earthquake benefited the study of Earth’s interior?

D. Why is California more likely to experience earthquakes than Montana? Chapter 19 – Earthquakes Study Guide

Answer Section

MODIFIED TRUE/FALSE 1. ANS: T 6. ANS: F 2. ANS: F 7. ANS: T 3. ANS: F 8. ANS: T 4. ANS: T 9. ANS: F 5. ANS: F 110. ANS: T

MULTIPLE CHOICE 11. ANS: A 20. ANS: 29. ANS: D 12. ANS: B 21. ANS: C 30. ANS: B 13. ANS: A 22. ANS: A or C 31. ANS: C 14. ANS: B 23. ANS: A 32. ANS: B 15. ANS: A 24. ANS: D 33. ANS: B 16. ANS: C 25. ANS: B 34. ANS: B 17. ANS: D 26. ANS: D 35. ANS: C 18. ANS: A 27. ANS: A 36. ANS: A 19. ANS: D 28. ANS: A

COMPLETION 37. ANS: normal fault 38. ANS: reverse fault 39. ANS: strike-slip fault 40. ANS: fault plane

OPEN RESPONSE 41. A. Point B is the epicenter of the earthquake because after all three seismograms calculated their distance from the epicenter and drew a circle of all possible points that the epicenter could be, the one spot where all three circles overlapped is point B.

B. They could still be used to determine the epicenter, but there would still need to be a third seismogram reading in order to pinpoint the exact location of the epicenter. By using only two stations, there would be two points of intersection where the epicenter would possibly be located.

C. By analyzing the changes in direction and speed of P-waves and S-waves, scientists have been able to learn about Earth’s interior. Because S-waves to not travel through Earth’s center it was concluded that some of Earth’s core is liquid which does not allow the back-and-forth motion of the wave to travel through it. Also, as the waves slow down and then speed back up scientists were able to determine the composition and thickness of the layers of Earth’s interior.

D. California lies along the Circum-Pacific Belt which is a tectonic plate boundary where 80 percent of all earthquakes occur. The movements along these boundaries cause earthquakes. Since Montana is not located above a boundary it is less likely to experience an earthquake.