Name Caleigh Kehoe Learning Unit 4 Earthquake Review Ques ons This assignment is designed to assess your understanding of Unit 4 and includes some of the Ques ons for Review at the end of Chapters 3 and 4 from your text plus a few addi onal ques ons Each ques on 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 le and send it back for evalua on and grading through the assignment tab by or before the due date 1 What is meant by the elas c rebound theory The elas c rebound theory is an explana on for how energy is spread during earthquakes 2 What is the di erence between the epicenter and the focus of an earthquake The focus of an earthquake is the exact point underground where the earthquake rupture starts measured in la tude longitude and also depth The epicenter is the la tude longitude point on the ground directly above the focus 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 Extension of the Earth s crust generally causes normal faults while a ri or spreading would produce such a fault or faults 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 generally causes reverse or thrust faults while ocean con nent or con nent con nent collision would produce such a fault or faults 5 What is the mo on of a P waves an S wave Surface waves P waves can travel through solids liquids and even gases S waves shake the ground in a shearing or crosswise mo on that is perpendicular to the direc on of travel 6 Which type of earthquake waves do the most damage Surface waves are the slowest but they do the most damage in an earthquake as they travel along the surface 7 In what order do seismic waves arrive to distant loca ons 8 How do seismologists determine how far away an earthquake was from their seismograph They determine the me lag between the P and S wave arrival and knowing the di erent veloci es of those waves calculate the distance The me lag increases the farther they are form the earthquake 9 How do seismologists determine the loca on of an earthquake epicenter They determine the distance of the earthquake from at least three seismograph of quite di erent loca ons and draw circles of distance from each seismograph The earthquake was at the intersec on of the three distance circles 10 What does the Richter Magnitude Scale depend on The Richter Magnitude Scale depends on the maximum amplitude of earthquake waves on the seismograph 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 The amount of energy released however increases by a factor of about 32 Looking at the same magnitudes a magnitude 6 0 earthquake releases 32 mes more energy than a magnitude 5 0 and a 7 0 quake releases 1 000 mes more energy than a 5 0 quake 12 What are the three main factors that a ect moment magnitude The three main factors that a ect moment magnitude are shear strength of the rocks displaced total surface area of rocks ruptured by the fault movement and average slip distance on the fault 13 What does the Mercalli Intensity Scale depend on Mercalli Intensity Scale depends on how much damage occurred in the area 14 In addi on to the amount of damage increases in what factors go along with an increase in earthquake magnitude In addi on to the amount of damage increases in fault o set length of fault ruptured accelera on o the ground me of shaking velocity of mo on of the ground go along with an increase in earthquake magnitude 15 Why are structures built on so sand or mud o en destroyed in an earthquake when nearby structures built on bedrock remain essen ally undamaged Bedrock shakes with small amplitude vibra ons the so sediment shakes with stronger larger amplitude vibra ons meaning greater back and forth distances 16 What is liquefac on Liquefac on takes place when loosely packed water logged sediments at or near the ground surface lose their strength in response to strong ground shaking Liquefac on occurring beneath buildings and other structures can cause major damage during earthquakes 17 What kinds of structural materials make dangerously weak walls during an earthquake Bricks concrete blocks stone or adobe mud make dangerously weak walls during an earthquake 18 What type of wall strengthening is commonly used to prevent a building from being pushed over laterally during an earthquake The diagonal beams is commonly used to prevent a building from being pushed over laterally during an earthquake 19 What can be done to a building either during construc on or a er to reduce the shaking of the building during an earthquake and therefore reduce the possibility of severe damage By using base isola on pads between the building and its founda on the base isola on pads act as shock absorbers to minimize transfer of ground shaking to the building 20 Freeway overpasses o en collapse in a strong earthquake even though their supports are concrete and heavy duty steel reinforcing bars Why Shaking in the earthquake cracks and crumbles the concrete that leaves the rebar without lateral support so it bends and the freeway collapses 21 Why are building res so hard to ght a er an earthquake Most earthquake damage results from the sudden release of energy in the form of seismic waves wave mo on and surface rupture physical slippage of the earth s crust Mul ple post earthquake res and physical damage can delay re service responses and reduce or exhaust water supples In addi on ammable gas or ignitable liquid releases and re protec on impairments create signi cant post earthquake re hazards 22 List several of the precursors that have been used to indicate that an earthquake may be coming Some indica ons that an earthquake may be coming are micro earthquakes changes in groundwater level increase in radon in water strange animal behavior 23 There has been at least one highly successful predic on of a major earthquake that saved a very large number of lives Where and when was that earthquake What informa on lead to the predic on The earthquake was in Haicheng China in 1975 and numerous foreshocks and very strange animal behavior lead to
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