Name: Joshua FernandezLearning Unit 4: Earthquake Review QuestionsThis assignment is designed to assess your understanding of Unit 4 and includes some of the Questions for Review 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”?- How energy is spread during earthquakes2. What is the difference between the epicenter and the focus of an earthquake?- The focus is the point on the fault where ruptures occur and the location from which seismic waves are released, epicenter is the location directly above the focus on the earth’s surface3. 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?- Causes normal faults, rift boundaries4. 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?- Causes reverse or thrust faults, ocean-continent or continent-continent boundaries5. What is the motion of a P-waves? an S-wave? Surface waves?- P-waves: compress and extend in the direction of wave travel.- S-waves: travel at right angles to the direction of wave motion- Surface waves: travel parallel to the earth’s surface6. Which type of earthquake waves do the most damage?- Surface waves7. In what order do seismic waves arrive to distant locations?- First would be P-waves, then S-waves, followed by surface waves8. How do seismologists determine how far away an earthquake was from their seismograph?- Based on the lag time between the p waves and s waves to calculate the distance of an earthquake9. How do seismologists determine the location of an earthquake epicenter?- Measuring the difference in time between the p and s waves 10.What does the Richter Magnitude Scale depend on?- Based on the highest amplitude wave measured on a seismogram11.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?- Almost 30x more energy, 60x more energy12.What are the three main factors that affect moment magnitude?- Rock strength, area of rock broken, amount of offset across the fault13.What does the Mercalli Intensity Scale depend on?- How strong people felt and how much damages has happened14.In addition to the amount of damage, increases in what factors go along with an increase inearthquake magnitude?- Increase in time of the shaking15.Why are structures built on soft sand or mud often destroyed in an earthquake when nearby structures built on bedrock remain essentially undamaged?- Bedrock shakes with smaller amplitude vibrations, soft sand or mud shakes with stronger vibrations16.What is liquefaction?- Quicksand like condition that happens in water saturated soil and rock, earthquakes causes the soil and rock to weaken, making buildings sink17.What kinds of structural materials make dangerously weak walls during an earthquake?- Brick and stone18.What type of wall strengthening is commonly used to prevent a building from being pushedover laterally during an earthquake?- Having shear walls, which are diagonal braces added to walls to keep the building from deforming. 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?- Have base isolation, putting the building n large rubber pads to allow the ground to move under the building20.Freeway overpasses often collapse in a strong earthquake, even though their supports are concrete and heavy duty steel reinforcing bars. Why?- The concrete is getting cracked and weakened, only leaving the steel bars resulting in bending21.Why are building fires so hard to fight after an earthquake?- Because of broken water mains22.List several of the precursors that have been used to indicate that an earthquake may be coming.- Ground deformation, foreshocks, water level in wells, abnormal animal behavior 23.There has been at least one highly successful prediction of a major earthquake that saved avery large number of lives. Where and when was that earthquake? What information lead to the prediction?- 1975 in northeastern China, foreshock activity, bulging of ground surface near fault, changes in groundwater levels, strange animal behavior.24.What is a seismic gap, and what is its significance?- Is a section of an active fault that has not had a recent earthquake. Since it was inactive for so long, there could be energy storing up for a strong earthquake in the near future. 25.Some major faults show migration with time (e.g. over the past few hundred or a thousand years), of earthquakes along the fault. Name one such fault – or indicate exactly where it is.- North Anatolian Fault in
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