Name Muminah Ramadan Learning Unit 4 Earthquake Review Questions This 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 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 faults occur 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 that saved 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 or a thousand years of earthquakes along the fault Name one such fault or indicate exactly
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