Name: Muminah RamadanLearning Unit 4: Earthquake Review QuestionsThis assignment is designed to assess your understanding of Unit 4 and includes some of the Questions forReview at the end of Chapters 3 and 4 from your text plus a few additional questions. Each question can be answered in one to two sentences. Please limit yourself to a maximum of three sentences. Access the assignment, complete it with ANSWERS IN A DIFFERENT COLOR FONT as a separate file, and send it back for evaluation and grading through the assignment tab by or before the due date. 1. What is meant by the “elastic rebound theory”?This theory is the movement between two sides of a fault which leads it to bending the rocks which make them slip which causes an earthquake.2. What is the difference between the epicenter and the focus of an earthquake?The epicenter is the center of the earth’s surface which is in the middle of the earthquake. The focus is the rupture point that makes an earthquake on the fault.3. Extension of the Earth’s crust generally causes what type of fault or faults? What type of plate boundary would produce such a fault or faults?The extension of the earth’s crust can cause a normal fault and these normal faults occur when there is a divergent plate boundary.4. Compression of the Earth’s crust generally causes what type of fault or faults? What type of plate boundary would produce such a fault or faults?Compression of the earth’s crust causes a blind thrust fault, and the blind thrust faultsoccur near tectonic plate margins.5. What is the motion of a P-waves? an S-wave? Surface waves?P waves travel with alternating compression and extensions when it moves through the rocks. S waves travel in a wiggling motion perpendicular to the direction of wave travel. Surface waves travel in a rolling motion or circular motion in both vertical and horizontal directions.6. Which type of earthquake waves do the most damage?Surface waves have the most ground motion and would cause the most damage.7. In what order do seismic waves arrive to distant locations?P waves come first. Next are the S waves. Lastly are the surface waves.8. How do seismologists determine how far away an earthquake was from their seismograph?The seismologists show how far away earthquakes are from the seismographs based on the time between the waves. They know the velocity of the waves as well. The difference would be the two waves to show the distance from the earthquakes.9. How do seismologists determine the location of an earthquake epicenter?Seismologists know the location of the earthquake’s epicenter based on the distance. Then they are able to see the circles of waves that overlap with each other.10. What does the Richter Magnitude Scale depend on?It depends on how close the earthquake is. It relies on if the earthquakes are closer to have an accurate reading of the scale.11. How much greater energy is released by a magnitude 6 earthquake than a magnitude 5 earthquake? How much greater energy is released by a magnitude 7 earthquake than a magnitude 5 earthquake?An earthquake with a magnitude of 6 has 32 times the amplitude than an earthquake that has a magnitude of 5. An earthquake with a magnitude of 7 releases 1,800,000,000. The amplitude of an earthquake with a magnitude of 5 releases 1,800,000 which makes it 1,000 times greater.12. What are the three main factors that affect moment magnitude?The strength of the rocks multiplies by both the surface of the earthquake and the distance on the fault.13. What does the Mercalli Intensity Scale depend on?It depends on the amount of damage that an earthquake caused to people and structures and it is written in roman numerals.14. In addition to the amount of damage, increases in what factors go along with an increase in earthquake magnitude?Increases in shaking ripples go with the increase in earthquake magnitude. The increase in the magnitude is an effect of how much energy is released by the earthquake.15. Why are structures built on soft sand or mud often destroyed in an earthquake when nearby structures built on bedrock remain essentially undamaged?it is destroyed because it can be moved easier since is it soft. The earthquakes make this soft ground shake more because it is so soft, so it gets destroyed.16. What is liquefaction?When soils that are solid becomes liquid when it is shaken by an earthquake.17. What kinds of structural materials make dangerously weak walls during an earthquake?Any materials that are loosely packed together and have big areas for water to come in.18. What type of wall strengthening is commonly used to prevent a building from being pushed over laterally during an earthquake?The diagonal steel beans which add support to the walls.19. What can be done to a building, either during construction or after, to reduce the shaking of the building during an earthquake and therefore reduce the possibility of severe damage?A building that is smaller and built on bedrock as well. Bedrock is more stable to be built on because it has higher frequencies during earthquakes.20. Freeway overpasses often collapse in a strong earthquake, even though their supports are concrete and heavy-duty steel reinforcing bars. Why?They are built on softer land which breaks easier and has no concrete to hold is steady.21. Why are building fires so hard to fight after an earthquake?There are broken wires that put gas into the air which can cause a fire. By this happening, the water mains could also be damaged.22. List several of the precursors that have been used to indicate that an earthquake may be coming.Some of the precursors that have been used to indicate that the earthquake may be coming would be foreshocks, changes in ground elevation, radon gas emissions, and changes in groundwater levels as well.23. There has been at least one highly successful prediction of a major earthquake thatsaved a very large number of lives. Where and when was that earthquake? What information lead to the prediction?The prediction was for an earthquake that was in Haicheng, China. The ground there was very shaky, and they predicted that there would be an earthquake there because of that.24. What is a seismic gap, and what is its significance?It is a section of a fault that has not been in a recent earthquake. Earthquakes that are somewhere else on that same fault show that the gap can cause an earthquake.25. Some major faults show migration with time (e.g., over the past few hundred
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