Read & Learn Earthquakes & Faults

Transcription

1 Read Earthquakes & Faults Read the provided article. Use the information in the reading to answer the questions on the task cards on your answer sheet. Make sure your answers are in the correct spot on the answer sheet.

2 Earthquakes & Faults The outer layer of the earth is the crust. The crust is broken into large pieces called tectonic plates. These plates fit together like pieces of a puzzle. The places where the tectonic plates come together are known as plate boundaries. Cracks in the crust around these boundaries are called fault lines. They may be small or very large. Most earthquakes occur along these fault lines. Most of the time, the crust on either side of the fault is moving too slowly for us to notice, but sometimes stress (pressure) builds up and the rocks that make up the crust suddenly slip, causing a great deal of movement all at once. There are three main types of faults. The type of fault depends on how adjacent blocks of rock move relative to each other. The San Andreas Fault the most famous fault in the United States is a strike-slip fault. This means two sections of crust (called fault blocks) are moving past each other. After an earthquake along a strike-slip fault, railroad tracks, roads, and other long structures can show bends and shifts; and buildings can collapse. In a normal fault, the crust moves vertically (up and down). They is usually associated with divergent plate boundaries. A stretching or pulling force called tension weakens the crust until the rock fractures, and one block of rock moves downward relative to the other. A reverse fault is usually associated with convergent plates. A pushing force called compression pushes crust together and forces a fault block upward. A thrust fault is a special kind of reverse fault that occurs at oceanic-oceanic convergent boundaries. This type of fault happens at subduction zones. At a thrust fault, a plate below the sea is moving under another plate, thrusting its edge upward. Thrust faults can produce larger earthquakes than strike-slip faults. Tsunamis can result from earthquakes caused by thrust faults too. The Earth s crust may seem hard and stiff, but it s really rather elastic. It has the ability to stretch and store energy like a spring. The stored energy is what enables earthquakes to happen. Earthquakes can be explained by the elastic rebound theory. The elastic rebound theory states that which stress or pressure is applied to rock over a period of time. The stress is caused by two plates moving in different directions, or in the same direction at different speeds. As the stress builds up, rock or a locked fault (a fault where the two sides are held together by friction) bends and changes shape. This is called elastic deformation. Eventually, the stress overpowers the rock's strength or the fault's friction, and either the rock fractures or the fault slips. Energy is s released that sets an earthquake in motion. The rock or fault bounces back, or rebounds, and the process may begin again.

3 Read & 1. Define a REVERSE FAULT. Read & 2. Define a NORMAL FAULT. Read & 3. Define a THURST FAULT. Read & 4. Define a STRIKE-SLIP FAULT.

4 Read & 5. Define ELASTIC DEFORMATION. Read & 6. Define ELASTIC REBOUND. Read & Read & 7. Define COMPRESSION. 8. Define TENSION.

5 Read & Read & 9. Define FAULT. 10. Around what type of plate boundary do reverse & thrust faults tend to occur? Read & 11. Around what type of plate boundary do normal faults tend to occur? Read & 12. Around what type of plate boundary do strikeslip faults tend to occur?

6 Read Earthquakes Scales Read the provided article. Use the information in the reading to answer the questions on the task cards on your answer sheet. Make sure your answers are in the correct spot on the answer sheet.

7 Earthquake Scales Magnitude is a measure of the amount of energy released during an earthquake There are several scales used to measure the magnitude of earthquakes. The first widely-used method was the Richter scale. This scale was developed by Charles F. Richter in It used a formula based on amplitude of the largest wave recorded on a specific type of seismometer and the distance between the earthquake and the seismometer. Unfortunately, the Richter scale, does not provide accurate estimates for large magnitude earthquakes. Today the moment magnitude scale is used most often because it works over a wider range of earthquake sizes. Magnitude scales can be used to describe earthquakes so small that they are expressed in negative numbers. The scale also has no upper limit, so it can describe earthquakes of so far unexperienced intensity, such as magnitude 10.0 and beyond. Another way to measure the strength of an earthquake is to use the Mercalli scale. This scale was invented by Giuseppe Mercalli in 1902, and uses the observations of the people who experienced the earthquake to estimate its intensity. The Mercalli scale is not as precise as magnitude scales because it depends on the observations of people.

8 Read & Read & 13. Define MAGNITUDE. 14. Name two magnitude scales. Read & 15. Why is the moment magnitude scale most often used? Read & 16. Describe the Mercalli scale.

9 Watch Watch the video at Use the information in the video to answer the questions on the task cards on your answer sheet. Make sure your answers are in the correct spot on the answer sheet.

10 Watch 17. What is an earthquake? Watch 18. What are the Earth s plates? Watch 19. Define SEISMIC WAVES. Watch 20. Define INTENSITY.

11 Watch 21. What are seismologists? Watch 22.What is a seismic moment? Watch 23. What can earthquakes form? Watch 24. Why do rocks in the Earth move?

12 Explore Do the exploration provided. Use what you have learned to answer the questions on the task cards on your answer sheet. Make sure your answers are in the correct spot on the answer sheet.

13 Explore Notice the line on the balloon. Stretch the balloon to make the line get linger and shorter. This pulling is a force called TENSION.

14 Explore 25. Draw a sketch of the balloon and line before and during stretching. Explore 26. What happens to the surface of the Earth after an earthquake caused by tension? Explore 27. What type of fault is caused by tension? Normal Reverse Strike-slip Explore 28. Draw a diagram of this type of fault.

15 Explore More Do the exploration provided. Use what you have learned to answer the questions on the task cards on your answer sheet. Make sure your answers are in the correct spot on the answer sheet.

16 Explore More Push the sponge from both ends to make it crumple in the middle. The crumpling is called uplift. The pushing is a force called COMPRESSION.

17 Explore 29. Draw a sketch of the sponge before and during pushing. Explore 30. What happens to the surface of the Earth after an earthquake caused by compression? Explore 31. What type of fault is caused by compression? Normal Reverse Strike-slip Explore 32. Draw a diagram of this type of fault.

18 Explore Again Do the exploration provided. Use what you have learned to answer the questions on the task cards on your answer sheet. Make sure your answers are in the correct spot on the answer sheet.

19 Explore Again Put the two blocks side-by-side. Push one block up and one block down. The side-by-side force is called SHEARING.

20 Explore 37. Draw a sketch of the blocks before and during pushing. Explore 38. What happens to the surface of the Earth after an earthquake caused by shearing? Explore 39. What type of fault is caused by shearing? Normal Reverse Strike-slip Explore 40. Draw a diagram of this type of fault.

21 Investigate Do the investigation provided at Use what you have learned to answer the questions on the task cards on your answer sheet. Make sure your answers are in the correct spot on the answer sheet.

22 Earthquake Testing Zone Click the switch to read a little more. Move your mouse to define terms. Read about earthquakes. Click to see what happens at different magnitudes.

23 Investigate 41. How often do earthquakes happen? Investigate 42. Why do scientists and engineers study earthquakes? Investigate 43. What is a seismograph? Investigate 44. What happens to buildings in a magnitude 8.9 earthquake?

24 Investigate 45. What happens to buildings in a magnitude 5.4 earthquake? Investigate 46. What happens to buildings in a magnitude 7.9 earthquake? Investigate 47. What happens to buildings in a magnitude 2.1 earthquake? Investigate 48. What happens to buildings in a magnitude 5.4 earthquake?

25 Sort Sort the information into three categories Have your teacher check your work before you move on. Make sure your answers are in the correct spot on the answer sheet.

26

27 Write You may use your device and/or textbook for this station. Write a paragraph (at least 5 sentences) to answer each prompt. Do 49 & 51 or 50 & 52. Make sure your answers are in the correct spot on the answer sheet.

28 Write & 49. Describe the types of earthquake waves. Write & 50. Describe how energy travels through the Earth. Write & 51. Ancient peoples did not know the real causes of earthquakes, so they made up legends about why earthquakes happen. Write your own legend about why earthquakes happen. Write & 52. In some parts of the world people have to worry about earthquakes. What do you think it would be like to live in an area of the world where this could happen?

29 Draw Use the map pencils to draw P-waves S-waves Epicenter Focus You may use your device to research the information you need to make your drawings. Make sure your answers are in the correct spot on the answer sheet.

30 Draw & Draw & 53. Draw P-waves. 54. Draw S-waves. Draw & 55. Draw an epicenter. Draw & 56. Draw a focus.