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Virginia Tech - GEOS 1034 - Study Guide - Midterm

Created by: Katherine Elite Notetaker

Virginia Tech - GEOS 1034 - Study Guide - Midterm

School: Virginia Polytechnic Institute and State University
Department: Geoscience
Course: Geoscience
Professor: Ying Zhou
Term: Fall 2018
Tags:
Name: Study Guide for Exam 1
Description: plate boundaries, types of tension, plate tectonics, crust, core, mantle, faults Everything from Unit 1
Uploaded: 09/12/2018
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background image Heat collisions made the young earth hot enough to melt its interior, allowing  heavy minerals (iron and nickel) to Sink to the inner earth a. 1. The sinking of heavier minerals led the Earth's interior to differentiate into a  _____, ______, and ______that then froze in place as the Earth cooled Core, mantle, crust a. 2. The Earth's inner core is under too much _____ to be liquid Pressure a. 3. Place tectonics: cold strong _____ float over warm weak _____ Lithosphere, asthenosphere a. Only happens in the core b. Driven by mantle convection, slab pull, and gravitational potential energy  (GPE) --> cools Earth's hot interior Convection- process where heat is transferred through liquid i. c. 4. Tectonic plates slide past each other in 3 different ways Convergent, divergent, transform Convergent- one moves beneath another  § Get reverse faulting i. Divergent- going away from each other  § New plate boundaries formed, rising from asthenosphere
§ Ex. Mid-Atlantic ridge
§ Mid-ocean ridges: where new ocean plate is created ii. Transform- 2 plates slide past each other in opposite directions iii. a. b. There is NO space between tectonic plates 5. Plate tectonics is driven by mantle convection (tractions), forces from gpe and  ____ a. Slab pull- gravitational force in subduction zones □ Gravitational potential energy- high/low topography, divergent  forces at top of mountains, converge forces in valleys (ridge push) § Change btw high and low topography causes movement □ Convection- heat is transferred through liquid  § Ex: lava lamp: top cools, bottom heats to there is a continuous  movement of wax rising and falling 6. Age of continental crust: ____ are the oldest, coldest parts of Earth's outer rigid  shell Craton a. 7. Most earthquakes occur during _____ interface Wadati-benioff- on interface between 2 plates i. What occurs here is a mega-thrust: one tectonic plate is forced  underneath another a. 8. Could plate tectonics have influenced evolution? Yes a. 9. The earth's magnetic field arises from _________ Convection in the OUTER core; dynamo effect a. 10. Magnetic field arises from complex motion associated with convection within  the outer core called ____ Dynamo effect- explains the origin of the Earth's main magnetic field in  terms of self-sustaining dynamo a. 11. What does this evidence (alternating lava flow) tell us about the Earth?  Magnetic pole reversal- related to change in convective movement of  liquid material in outer core and processes occurring in inner core a. 12. Is there any evidence that mass extinctions will occur if we lose our magnetic  field? No a. 13. What happens at a mid-oceanic ridge? Divergent plate boundary  a. New oceanic crust is forming b. 14. Why do we need 4 satellites to get a position? To get longitude, latitude, time and height a. 15. Diamonds come from a rare type of volcanic eruption that brought them up from  great depths at great speed. What depths? Between 100 and 250 km a. 16. What is the main ingredient in the formation of Geodes? Water a. b. Formed close to Earth's surface 17. Why are some of the largest earthquakes not the most deadly? Population of area a. Structure of buildings b. c. Places where earthquakes are common are more prepared to deal with  them 18. Two processes describe the earthquake cycle: Elastic rebound theory: the crust deforms elastically (storing energy), then  rebounds (like a ball) i. More movement closer to the fault ii. If occurs in subduction zone, this is the most dangerous a. Strike-slip behavior: a fault remains locked while energy builds, then slips  suddenly b. 19. Stick-slip behavior occurs because of friction: rough spots along the fault called  _____ prevent the fault from sliding until they're broken Asperities a. 20. 3 types of faults arise from 3 types of stress states: Extensional : normal fault (hanging wall moves down relative to footwall) a. Compressional: reverse fault (hanging wall moves up) b. Sheer stress: strike-slip fault (walls move sideways) c. 21. In addition to surface waves, earthquakes cause ___ that travel through the  interior of the earth Body waves a. 22. 2 types of body waves: P waves- faster than S waves, weakest, can travel through solids, liquids,  and gases, push pull motion, compressional a. S waves- travel through ONLY solids, travel slower, produce side to side  motion (sideways, sheer) b. Travel through interior of earth c. Can be used to locate an earthquake d. 23. 2 types of surface waves: Love waves- horizontal motion at center, side-to-side motion a. Rayleigh waves- movement that looks like a wave (up-down motion) b. Stronger/last to arrive c. Travel along crust, travel SLOW d. e. Cause most of the damage near epicenter 24. Reconstruction of plate motions starting from 180 million years ago (the  breakup of supercontinent ____) Pangea a. 25. Mercalli scale- how people and buildings perceive shaking 26. Sediments in the Santa Rosa Basin greatly magnified the amplitude and duration  of shaking during the 1906 earthquake. What was the main reason? Loose sediments that weren't compacted together a. 27. Why do geoscientists use GPS? To measure surface movements a. b. Allow us to predict how big an earthquake will be, knowing slip deficit  rate and time since last earthquake enables a forecast of potential size of 
next earthquake
c. To figure out where an earthquake could occur 28. How do we know the Earth is not hollow? Lab experiments Show that rocks are too weak at high temperatures and  pressures in Earth a. Passage of seismic waves show no voids b. Magnitude of our gravity requires dense solid interior c. No physics to build without hollow planet  d. 29. Why is the seismic hazard high in central US? Large earthquakes in 1811 and 1812  a. 30. Seismic waves can be used to study the Earth's ____ Interior a. 31. 1976 Tangshan and 2010 Haiti earthquakes were amongst deadliest earthquakes  in past century Wenchuan- 87,000 perished Over 7,000 poorly built schools collapsed, killing about 10,000  students Brave police officers were able to save several children before a  landslide further demolished the school Landslides occurred a. b. 2005 Kashmir earthquake- Concrete floors are heavy and w/o proper steel  reinforcement and lateral support can lead to pancake during an 
earthquake
Once surface waves arrive, poorly constructed buildings fall fast c. 32. Earthquake magnitude is logarithmic scale: for every whole # increase in  magnitude, the amplitude of shaking goes up by a factor of 10 33. In the real world: Faults are generally steadily loaded a. Earthquakes don't occur at same stress level b. Earthquakes are not same magnitude and are NOT predictable c. We can use past earthquakes to estimate probability of future earthquakes d. 34. What do you do during an earthquake? If indoors in a well engineered building Stay indoors i. Drop to the ground; take cover under a table ii. Stay away from glass and anything that could fall iii. Use a doorway for shelter only if you know it's a strongly supported,  loadbearing doorway iv. DO NOT use elevators v. a. If indoors in a poorly constructed building Get out of building as fast as possible i. b. If outdoors Stay outdoors, move away from buildings i. c. Get off bridges that have potential to sway d. Shut down heavy machinery e. Stop surgeries f. 35. Diagonal beams provide resistance to SHEARING that often cause buildings to  collapse  36. Buildings can fall over due to  a. Liquefaction- the strength and stiffness of a soil is reduced by earthquake  shaking or other rapid loading. 37. Approaching to reducing swaying of buildings: Diagonal beams provide resistance to shearing that often causes buildings  to collapse Shearing- one beam gets shorter and one gets longer i. a. Put in corner studs to improve stability b. In sediment, put pilings down into bedrock to stabilize c. Isolation system Building with rubber laminations to steel shim plates to allow the  building to withstand shearing i. d. Inertial damping systems Allows building to sway around weighted material i. e. 38. Earthquake early warning system Seismic waves travel slower than speed of light, we can detect earthquake  and communicate warning ahead of shaking a. 39. Forced resonance: when the ____ of external forces matches the natural ____ of  a structure Frequency, frequency a. 40. 41. What is the lithosphere?  a. The strong outer shell, consists of crust and upper mantle 42. What is the asthenosphere?  a. Warm, weak regions that allow tectonic plates to move 43. What is a subduction zone?  a. A location where one plate dives beneath another, convergent boundary 44. What formed from India crashing into Eurasia?  a. Tibetan plateau  45. What is a fault? a. semi planar fracture or fracture system has moved relative to the other side b. Friction along boundary between boards slow motion  i. Rough edges break off and motion occurs along the plane ii. One lithospheric plate moving past another is slowed by friction  along fault plane that separates the plates 46. What is the difference between stress and strain? a. stress- force that results from plate tectonic movements b. Strain- change in shape or location of rocks due to applied stress 47. What are the 4 stages of earthquakes? a. Long period of inactivity b. Accumulated elastic strain produces small earthquakes c. Foreshocks- occur hours or days prior to next earthquake, small to  moderate sized earthquakes that occur before main event (may not always 
occur)
d. Mainshock- major earthquake and aftershocks a. Aftershock- smaller earthquake occurring near location of  mainshock Can occur anywhere from a few minutes to a year after the  main event i. 48. What is the difference between earthquake magnitude and earthquake intensity? a. Earthquake magnitude measures energy released at the source of an  Earthquake as determined by seismographs ○ Richter scale- measures magnitude specific to one spot, measures  max amount of ground shaking due to S wave ○ Moment magnitude scale- measures actual energy released during  earthquake, determines absolute size of earthquake i. Uses amount of slippage, area of ruptured plane, and rigidity  of rocks near focus of quake b. Earthquake intensity- measures strength of shaking produced by  earthquake at specific locations a. Mercalli scale 49. How can a scientist find the distance to the epicenter? a. Seismograph stations that are farthest from epicenter will observe greatest  difference between P and S wave arrival times b. Distance to epicenter calculated for each of 3 graphs, respective values  used for radius of circle drawn around each seismic station ○ They intersect in one location- the epicenter 50. What is the Global Earthquake model? a. Model- Modern effort to reduce seismic risk worldwide ○ Produced global strain rate model to show where there is more and  less deformation ○ Once there is more data, there must be an effort to improve models 51. Are there any reliable earthquake precursors? a. No ○ Foreshocks- sometimes occur before a bigger mainshock
○ Aftershock- always occur after a bigger mainshock
52. Where do the biggest earthquakes occur? a. on subduction zones b. Largest stress buildup c. Longest faults 53. Where do the deadliest earthquakes occur? a. Interior plates b. Largest populations c. Bad building practices What 2 natural disasters are linked with earthquakes? a. Fire ○ SF 1906- water mains broke, gas lines rupturing, firefighters  couldn't get to parts b. Landslides c. Disease outbreaks ○ Loss of sanitation
○ Loss of housing
○ Disruption of public health services
○ Ruptured sewer/water lines that cause water to become 
contaminated 54. 55. What are some observations made before earthquakes? (these do not predict how  active a fault will be) a. Shaking b. Gravity change c. Water table rose/fell before an earthquake d. Lights e. Abnormal animal behavior f. Dogs that barked Other important information: Continental rifts- spread and create new oceans, all oceans started this way
• Continental crust that is below is MORE dense
• Mountains and Icebergs both: ○ Float within denser material
○ Will eventually vanish
○ Most of their mass is beneath the surface
• Large solar flares- massive concentrations of charged particles
• Magma- hot flow within volcano
Lava- hot flow that comes out
• Margin of continental and oceanic crust are NOT plate boundaries
• Reflection seismology- allows visualization of crustal structure several km  down • Earthquake seismology uses seismic waves from earthquakes to visualize  Earth's deep interior § Can reveal subducting plates deep within Earth High density rocks are cold Low density rocks are warm • Epicenter- ruptured rocks break at this place to produce the earthquake Focus- initial breaking/rupturing within Earth Seismic waves- stored elastic strain energy, strong motion that can  be felt as they pass the ground beneath us • Largest earthquake on earth in past 100 years? Chilean Study Guide for Exam #1 Wednesday, September 12, 2018 3:43 PM
background image Heat collisions made the young earth hot enough to melt its interior, allowing  heavy minerals (iron and nickel) to Sink to the inner earth a. 1. The sinking of heavier minerals led the Earth's interior to differentiate into a  _____, ______, and ______that then froze in place as the Earth cooled Core, mantle, crust a. 2. The Earth's inner core is under too much _____ to be liquid Pressure a. 3. Place tectonics: cold strong _____ float over warm weak _____ Lithosphere, asthenosphere a. Only happens in the core b. Driven by mantle convection, slab pull, and gravitational potential energy  (GPE) --> cools Earth's hot interior Convection- process where heat is transferred through liquid i. c. 4. Tectonic plates slide past each other in 3 different ways Convergent, divergent, transform Convergent- one moves beneath another  § Get reverse faulting i. Divergent- going away from each other  § New plate boundaries formed, rising from asthenosphere
§ Ex. Mid-Atlantic ridge
§ Mid-ocean ridges: where new ocean plate is created ii. Transform- 2 plates slide past each other in opposite directions iii. a. b. There is NO space between tectonic plates 5. Plate tectonics is driven by mantle convection (tractions), forces from gpe and  ____ a. Slab pull- gravitational force in subduction zones □ Gravitational potential energy- high/low topography, divergent  forces at top of mountains, converge forces in valleys (ridge push) § Change btw high and low topography causes movement □ Convection- heat is transferred through liquid  § Ex: lava lamp: top cools, bottom heats to there is a continuous  movement of wax rising and falling 6. Age of continental crust: ____ are the oldest, coldest parts of Earth's outer rigid  shell Craton a. 7. Most earthquakes occur during _____ interface Wadati-benioff- on interface between 2 plates i. What occurs here is a mega-thrust: one tectonic plate is forced  underneath another a. 8. Could plate tectonics have influenced evolution? Yes a. 9. The earth's magnetic field arises from _________ Convection in the OUTER core; dynamo effect a. 10. Magnetic field arises from complex motion associated with convection within  the outer core called ____ Dynamo effect- explains the origin of the Earth's main magnetic field in  terms of self-sustaining dynamo a. 11. What does this evidence (alternating lava flow) tell us about the Earth?  Magnetic pole reversal- related to change in convective movement of  liquid material in outer core and processes occurring in inner core a. 12. Is there any evidence that mass extinctions will occur if we lose our magnetic  field? No a. 13. What happens at a mid-oceanic ridge? Divergent plate boundary  a. New oceanic crust is forming b. 14. Why do we need 4 satellites to get a position? To get longitude, latitude, time and height a. 15. Diamonds come from a rare type of volcanic eruption that brought them up from  great depths at great speed. What depths? Between 100 and 250 km a. 16. What is the main ingredient in the formation of Geodes? Water a. b. Formed close to Earth's surface 17. Why are some of the largest earthquakes not the most deadly? Population of area a. Structure of buildings b. c. Places where earthquakes are common are more prepared to deal with  them 18. Two processes describe the earthquake cycle: Elastic rebound theory: the crust deforms elastically (storing energy), then  rebounds (like a ball) i. More movement closer to the fault ii. If occurs in subduction zone, this is the most dangerous a. Strike-slip behavior: a fault remains locked while energy builds, then slips  suddenly b. 19. Stick-slip behavior occurs because of friction: rough spots along the fault called  _____ prevent the fault from sliding until they're broken Asperities a. 20. 3 types of faults arise from 3 types of stress states: Extensional : normal fault (hanging wall moves down relative to footwall) a. Compressional: reverse fault (hanging wall moves up) b. Sheer stress: strike-slip fault (walls move sideways) c. 21. In addition to surface waves, earthquakes cause ___ that travel through the  interior of the earth Body waves a. 22. 2 types of body waves: P waves- faster than S waves, weakest, can travel through solids, liquids,  and gases, push pull motion, compressional a. S waves- travel through ONLY solids, travel slower, produce side to side  motion (sideways, sheer) b. Travel through interior of earth c. Can be used to locate an earthquake d. 23. 2 types of surface waves: Love waves- horizontal motion at center, side-to-side motion a. Rayleigh waves- movement that looks like a wave (up-down motion) b. Stronger/last to arrive c. Travel along crust, travel SLOW d. e. Cause most of the damage near epicenter 24. Reconstruction of plate motions starting from 180 million years ago (the  breakup of supercontinent ____) Pangea a. 25. Mercalli scale- how people and buildings perceive shaking 26. Sediments in the Santa Rosa Basin greatly magnified the amplitude and duration  of shaking during the 1906 earthquake. What was the main reason? Loose sediments that weren't compacted together a. 27. Why do geoscientists use GPS? To measure surface movements a. b. Allow us to predict how big an earthquake will be, knowing slip deficit  rate and time since last earthquake enables a forecast of potential size of 
next earthquake
c. To figure out where an earthquake could occur 28. How do we know the Earth is not hollow? Lab experiments Show that rocks are too weak at high temperatures and  pressures in Earth a. Passage of seismic waves show no voids b. Magnitude of our gravity requires dense solid interior c. No physics to build without hollow planet  d. 29. Why is the seismic hazard high in central US? Large earthquakes in 1811 and 1812  a. 30. Seismic waves can be used to study the Earth's ____ Interior a. 31. 1976 Tangshan and 2010 Haiti earthquakes were amongst deadliest earthquakes  in past century Wenchuan- 87,000 perished Over 7,000 poorly built schools collapsed, killing about 10,000  students Brave police officers were able to save several children before a  landslide further demolished the school Landslides occurred a. b. 2005 Kashmir earthquake- Concrete floors are heavy and w/o proper steel  reinforcement and lateral support can lead to pancake during an 
earthquake
Once surface waves arrive, poorly constructed buildings fall fast c. 32. Earthquake magnitude is logarithmic scale: for every whole # increase in  magnitude, the amplitude of shaking goes up by a factor of 10 33. In the real world: Faults are generally steadily loaded a. Earthquakes don't occur at same stress level b. Earthquakes are not same magnitude and are NOT predictable c. We can use past earthquakes to estimate probability of future earthquakes d. 34. What do you do during an earthquake? If indoors in a well engineered building Stay indoors i. Drop to the ground; take cover under a table ii. Stay away from glass and anything that could fall iii. Use a doorway for shelter only if you know it's a strongly supported,  loadbearing doorway iv. DO NOT use elevators v. a. If indoors in a poorly constructed building Get out of building as fast as possible i. b. If outdoors Stay outdoors, move away from buildings i. c. Get off bridges that have potential to sway d. Shut down heavy machinery e. Stop surgeries f. 35. Diagonal beams provide resistance to SHEARING that often cause buildings to  collapse  36. Buildings can fall over due to  a. Liquefaction- the strength and stiffness of a soil is reduced by earthquake  shaking or other rapid loading. 37. Approaching to reducing swaying of buildings: Diagonal beams provide resistance to shearing that often causes buildings  to collapse Shearing- one beam gets shorter and one gets longer i. a. Put in corner studs to improve stability b. In sediment, put pilings down into bedrock to stabilize c. Isolation system Building with rubber laminations to steel shim plates to allow the  building to withstand shearing i. d. Inertial damping systems Allows building to sway around weighted material i. e. 38. Earthquake early warning system Seismic waves travel slower than speed of light, we can detect earthquake  and communicate warning ahead of shaking a. 39. Forced resonance: when the ____ of external forces matches the natural ____ of  a structure Frequency, frequency a. 40. 41. What is the lithosphere?  a. The strong outer shell, consists of crust and upper mantle 42. What is the asthenosphere?  a. Warm, weak regions that allow tectonic plates to move 43. What is a subduction zone?  a. A location where one plate dives beneath another, convergent boundary 44. What formed from India crashing into Eurasia?  a. Tibetan plateau  45. What is a fault? a. semi planar fracture or fracture system has moved relative to the other side b. Friction along boundary between boards slow motion  i. Rough edges break off and motion occurs along the plane ii. One lithospheric plate moving past another is slowed by friction  along fault plane that separates the plates 46. What is the difference between stress and strain? a. stress- force that results from plate tectonic movements b. Strain- change in shape or location of rocks due to applied stress 47. What are the 4 stages of earthquakes? a. Long period of inactivity b. Accumulated elastic strain produces small earthquakes c. Foreshocks- occur hours or days prior to next earthquake, small to  moderate sized earthquakes that occur before main event (may not always 
occur)
d. Mainshock- major earthquake and aftershocks a. Aftershock- smaller earthquake occurring near location of  mainshock Can occur anywhere from a few minutes to a year after the  main event i. 48. What is the difference between earthquake magnitude and earthquake intensity? a. Earthquake magnitude measures energy released at the source of an  Earthquake as determined by seismographs ○ Richter scale- measures magnitude specific to one spot, measures  max amount of ground shaking due to S wave ○ Moment magnitude scale- measures actual energy released during  earthquake, determines absolute size of earthquake i. Uses amount of slippage, area of ruptured plane, and rigidity  of rocks near focus of quake b. Earthquake intensity- measures strength of shaking produced by  earthquake at specific locations a. Mercalli scale 49. How can a scientist find the distance to the epicenter? a. Seismograph stations that are farthest from epicenter will observe greatest  difference between P and S wave arrival times b. Distance to epicenter calculated for each of 3 graphs, respective values  used for radius of circle drawn around each seismic station ○ They intersect in one location- the epicenter 50. What is the Global Earthquake model? a. Model- Modern effort to reduce seismic risk worldwide ○ Produced global strain rate model to show where there is more and  less deformation ○ Once there is more data, there must be an effort to improve models 51. Are there any reliable earthquake precursors? a. No ○ Foreshocks- sometimes occur before a bigger mainshock
○ Aftershock- always occur after a bigger mainshock
52. Where do the biggest earthquakes occur? a. on subduction zones b. Largest stress buildup c. Longest faults 53. Where do the deadliest earthquakes occur? a. Interior plates b. Largest populations c. Bad building practices What 2 natural disasters are linked with earthquakes? a. Fire ○ SF 1906- water mains broke, gas lines rupturing, firefighters  couldn't get to parts b. Landslides c. Disease outbreaks ○ Loss of sanitation
○ Loss of housing
○ Disruption of public health services
○ Ruptured sewer/water lines that cause water to become 
contaminated 54. 55. What are some observations made before earthquakes? (these do not predict how  active a fault will be) a. Shaking b. Gravity change c. Water table rose/fell before an earthquake d. Lights e. Abnormal animal behavior f. Dogs that barked Other important information: Continental rifts- spread and create new oceans, all oceans started this way
• Continental crust that is below is MORE dense
• Mountains and Icebergs both: ○ Float within denser material
○ Will eventually vanish
○ Most of their mass is beneath the surface
• Large solar flares- massive concentrations of charged particles
• Magma- hot flow within volcano
Lava- hot flow that comes out
• Margin of continental and oceanic crust are NOT plate boundaries
• Reflection seismology- allows visualization of crustal structure several km  down • Earthquake seismology uses seismic waves from earthquakes to visualize  Earth's deep interior § Can reveal subducting plates deep within Earth High density rocks are cold Low density rocks are warm • Epicenter- ruptured rocks break at this place to produce the earthquake Focus- initial breaking/rupturing within Earth Seismic waves- stored elastic strain energy, strong motion that can  be felt as they pass the ground beneath us • Largest earthquake on earth in past 100 years? Chilean Study Guide for Exam #1 Wednesday, September 12, 2018 3:43 PM
background image Heat collisions made the young earth hot enough to melt its interior, allowing  heavy minerals (iron and nickel) to Sink to the inner earth a. 1. The sinking of heavier minerals led the Earth's interior to differentiate into a  _____, ______, and ______that then froze in place as the Earth cooled Core, mantle, crust a. 2. The Earth's inner core is under too much _____ to be liquid Pressure a. 3. Place tectonics: cold strong _____ float over warm weak _____ Lithosphere, asthenosphere a. Only happens in the core b. Driven by mantle convection, slab pull, and gravitational potential energy  (GPE) --> cools Earth's hot interior Convection- process where heat is transferred through liquid i. c. 4. Tectonic plates slide past each other in 3 different ways Convergent, divergent, transform Convergent- one moves beneath another  § Get reverse faulting i. Divergent- going away from each other  § New plate boundaries formed, rising from asthenosphere
§ Ex. Mid-Atlantic ridge
§ Mid-ocean ridges: where new ocean plate is created ii. Transform- 2 plates slide past each other in opposite directions iii. a. b. There is NO space between tectonic plates 5. Plate tectonics is driven by mantle convection (tractions), forces from gpe and  ____ a. Slab pull- gravitational force in subduction zones □ Gravitational potential energy- high/low topography, divergent  forces at top of mountains, converge forces in valleys (ridge push) § Change btw high and low topography causes movement □ Convection- heat is transferred through liquid  § Ex: lava lamp: top cools, bottom heats to there is a continuous  movement of wax rising and falling 6. Age of continental crust: ____ are the oldest, coldest parts of Earth's outer rigid  shell Craton a. 7. Most earthquakes occur during _____ interface Wadati-benioff- on interface between 2 plates i. What occurs here is a mega-thrust: one tectonic plate is forced  underneath another a. 8. Could plate tectonics have influenced evolution? Yes a. 9. The earth's magnetic field arises from _________ Convection in the OUTER core; dynamo effect a. 10. Magnetic field arises from complex motion associated with convection within  the outer core called ____ Dynamo effect- explains the origin of the Earth's main magnetic field in  terms of self-sustaining dynamo a. 11. What does this evidence (alternating lava flow) tell us about the Earth?  Magnetic pole reversal- related to change in convective movement of  liquid material in outer core and processes occurring in inner core a. 12. Is there any evidence that mass extinctions will occur if we lose our magnetic  field? No a. 13. What happens at a mid-oceanic ridge? Divergent plate boundary  a. New oceanic crust is forming b. 14. Why do we need 4 satellites to get a position? To get longitude, latitude, time and height a. 15. Diamonds come from a rare type of volcanic eruption that brought them up from  great depths at great speed. What depths? Between 100 and 250 km a. 16. What is the main ingredient in the formation of Geodes? Water a. b. Formed close to Earth's surface 17. Why are some of the largest earthquakes not the most deadly? Population of area a. Structure of buildings b. c. Places where earthquakes are common are more prepared to deal with  them 18. Two processes describe the earthquake cycle: Elastic rebound theory: the crust deforms elastically (storing energy), then  rebounds (like a ball) i. More movement closer to the fault ii. If occurs in subduction zone, this is the most dangerous a. Strike-slip behavior: a fault remains locked while energy builds, then slips  suddenly b. 19. Stick-slip behavior occurs because of friction: rough spots along the fault called  _____ prevent the fault from sliding until they're broken Asperities a. 20. 3 types of faults arise from 3 types of stress states: Extensional : normal fault (hanging wall moves down relative to footwall) a. Compressional: reverse fault (hanging wall moves up) b. Sheer stress: strike-slip fault (walls move sideways) c. 21. In addition to surface waves, earthquakes cause ___ that travel through the  interior of the earth Body waves a. 22. 2 types of body waves: P waves- faster than S waves, weakest, can travel through solids, liquids,  and gases, push pull motion, compressional a. S waves- travel through ONLY solids, travel slower, produce side to side  motion (sideways, sheer) b. Travel through interior of earth c. Can be used to locate an earthquake d. 23. 2 types of surface waves: Love waves- horizontal motion at center, side-to-side motion a. Rayleigh waves- movement that looks like a wave (up-down motion) b. Stronger/last to arrive c. Travel along crust, travel SLOW d. e. Cause most of the damage near epicenter 24. Reconstruction of plate motions starting from 180 million years ago (the  breakup of supercontinent ____) Pangea a. 25. Mercalli scale- how people and buildings perceive shaking 26. Sediments in the Santa Rosa Basin greatly magnified the amplitude and duration  of shaking during the 1906 earthquake. What was the main reason? Loose sediments that weren't compacted together a. 27. Why do geoscientists use GPS? To measure surface movements a. b. Allow us to predict how big an earthquake will be, knowing slip deficit  rate and time since last earthquake enables a forecast of potential size of 
next earthquake
c. To figure out where an earthquake could occur 28. How do we know the Earth is not hollow? Lab experiments Show that rocks are too weak at high temperatures and  pressures in Earth a. Passage of seismic waves show no voids b. Magnitude of our gravity requires dense solid interior c. No physics to build without hollow planet  d. 29. Why is the seismic hazard high in central US? Large earthquakes in 1811 and 1812  a. 30. Seismic waves can be used to study the Earth's ____ Interior a. 31. 1976 Tangshan and 2010 Haiti earthquakes were amongst deadliest earthquakes  in past century Wenchuan- 87,000 perished Over 7,000 poorly built schools collapsed, killing about 10,000  students Brave police officers were able to save several children before a  landslide further demolished the school Landslides occurred a. b. 2005 Kashmir earthquake- Concrete floors are heavy and w/o proper steel  reinforcement and lateral support can lead to pancake during an 
earthquake
Once surface waves arrive, poorly constructed buildings fall fast c. 32. Earthquake magnitude is logarithmic scale: for every whole # increase in  magnitude, the amplitude of shaking goes up by a factor of 10 33. In the real world: Faults are generally steadily loaded a. Earthquakes don't occur at same stress level b. Earthquakes are not same magnitude and are NOT predictable c. We can use past earthquakes to estimate probability of future earthquakes d. 34. What do you do during an earthquake? If indoors in a well engineered building Stay indoors i. Drop to the ground; take cover under a table ii. Stay away from glass and anything that could fall iii. Use a doorway for shelter only if you know it's a strongly supported,  loadbearing doorway iv. DO NOT use elevators v. a. If indoors in a poorly constructed building Get out of building as fast as possible i. b. If outdoors Stay outdoors, move away from buildings i. c. Get off bridges that have potential to sway d. Shut down heavy machinery e. Stop surgeries f. 35. Diagonal beams provide resistance to SHEARING that often cause buildings to  collapse  36. Buildings can fall over due to  a. Liquefaction- the strength and stiffness of a soil is reduced by earthquake  shaking or other rapid loading. 37. Approaching to reducing swaying of buildings: Diagonal beams provide resistance to shearing that often causes buildings  to collapse Shearing- one beam gets shorter and one gets longer i. a. Put in corner studs to improve stability b. In sediment, put pilings down into bedrock to stabilize c. Isolation system Building with rubber laminations to steel shim plates to allow the  building to withstand shearing i. d. Inertial damping systems Allows building to sway around weighted material i. e. 38. Earthquake early warning system Seismic waves travel slower than speed of light, we can detect earthquake  and communicate warning ahead of shaking a. 39. Forced resonance: when the ____ of external forces matches the natural ____ of  a structure Frequency, frequency a. 40. 41. What is the lithosphere?  a. The strong outer shell, consists of crust and upper mantle 42. What is the asthenosphere?  a. Warm, weak regions that allow tectonic plates to move 43. What is a subduction zone?  a. A location where one plate dives beneath another, convergent boundary 44. What formed from India crashing into Eurasia?  a. Tibetan plateau  45. What is a fault? a. semi planar fracture or fracture system has moved relative to the other side b. Friction along boundary between boards slow motion  i. Rough edges break off and motion occurs along the plane ii. One lithospheric plate moving past another is slowed by friction  along fault plane that separates the plates 46. What is the difference between stress and strain? a. stress- force that results from plate tectonic movements b. Strain- change in shape or location of rocks due to applied stress 47. What are the 4 stages of earthquakes? a. Long period of inactivity b. Accumulated elastic strain produces small earthquakes c. Foreshocks- occur hours or days prior to next earthquake, small to  moderate sized earthquakes that occur before main event (may not always 
occur)
d. Mainshock- major earthquake and aftershocks a. Aftershock- smaller earthquake occurring near location of  mainshock Can occur anywhere from a few minutes to a year after the  main event i. 48. What is the difference between earthquake magnitude and earthquake intensity? a. Earthquake magnitude measures energy released at the source of an  Earthquake as determined by seismographs ○ Richter scale- measures magnitude specific to one spot, measures  max amount of ground shaking due to S wave ○ Moment magnitude scale- measures actual energy released during  earthquake, determines absolute size of earthquake i. Uses amount of slippage, area of ruptured plane, and rigidity  of rocks near focus of quake b. Earthquake intensity- measures strength of shaking produced by  earthquake at specific locations a. Mercalli scale 49. How can a scientist find the distance to the epicenter? a. Seismograph stations that are farthest from epicenter will observe greatest  difference between P and S wave arrival times b. Distance to epicenter calculated for each of 3 graphs, respective values  used for radius of circle drawn around each seismic station ○ They intersect in one location- the epicenter 50. What is the Global Earthquake model? a. Model- Modern effort to reduce seismic risk worldwide ○ Produced global strain rate model to show where there is more and  less deformation ○ Once there is more data, there must be an effort to improve models 51. Are there any reliable earthquake precursors? a. No ○ Foreshocks- sometimes occur before a bigger mainshock
○ Aftershock- always occur after a bigger mainshock
52. Where do the biggest earthquakes occur? a. on subduction zones b. Largest stress buildup c. Longest faults 53. Where do the deadliest earthquakes occur? a. Interior plates b. Largest populations c. Bad building practices What 2 natural disasters are linked with earthquakes? a. Fire ○ SF 1906- water mains broke, gas lines rupturing, firefighters  couldn't get to parts b. Landslides c. Disease outbreaks ○ Loss of sanitation
○ Loss of housing
○ Disruption of public health services
○ Ruptured sewer/water lines that cause water to become 
contaminated 54. 55. What are some observations made before earthquakes? (these do not predict how  active a fault will be) a. Shaking b. Gravity change c. Water table rose/fell before an earthquake d. Lights e. Abnormal animal behavior f. Dogs that barked Other important information: Continental rifts- spread and create new oceans, all oceans started this way
• Continental crust that is below is MORE dense
• Mountains and Icebergs both: ○ Float within denser material
○ Will eventually vanish
○ Most of their mass is beneath the surface
• Large solar flares- massive concentrations of charged particles
• Magma- hot flow within volcano
Lava- hot flow that comes out
• Margin of continental and oceanic crust are NOT plate boundaries
• Reflection seismology- allows visualization of crustal structure several km  down • Earthquake seismology uses seismic waves from earthquakes to visualize  Earth's deep interior § Can reveal subducting plates deep within Earth High density rocks are cold Low density rocks are warm • Epicenter- ruptured rocks break at this place to produce the earthquake Focus- initial breaking/rupturing within Earth Seismic waves- stored elastic strain energy, strong motion that can  be felt as they pass the ground beneath us • Largest earthquake on earth in past 100 years? Chilean Study Guide for Exam #1 Wednesday, September 12, 2018 3:43 PM

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School: Virginia Polytechnic Institute and State University
Department: Geoscience
Course: Geoscience
Professor: Ying Zhou
Term: Fall 2018
Tags:
Name: Study Guide for Exam 1
Description: plate boundaries, types of tension, plate tectonics, crust, core, mantle, faults Everything from Unit 1
Uploaded: 09/12/2018
9 Pages 147 Views 117 Unlocks
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