chapter 12

  1. what is an earthquake?
    sudden shaking of earth crust
  2. what are earthquakes sually associated with?
    rupture of a fault
  3. accumulated stress energy is released as _______
    seismic waves
  4. when seismic waves radiate through the earths interior and surface what does it cause?
  5. why do subduction zones have extreme earthquakes?
    two plates touching build up stress
  6. how many major cities lie on on near unstable regions of the earths crust?
  7. ground shaking produces:
    • sediment liquefaction
    • mass wasting (landslide)
    • building collapse
  8. explain elastic rebound theory:
    • crust at rest- no strain
    • crust deformed- strain build up
    • ruptured crust causing earthquake-elastic rebound
    • fractured crust, fault zone- strain released
  9. where do most earthquakes occur?
    • plate boundaires
    • intraplte seismicity also common
  10. explain intraplate earthquakes
    • shallow foci
    • soft weak area of plate interior
    • occur near pre existing plate boundaries
    • ex appalachian
  11. what are the sites of frequent earthquake activity?
    divergent, convergent and transform margins
  12. what is the epicenter and and focus point?
    epicenter is point on ground above focus and and focus is where earthquake occurred
  13. explain transform seismicity
    Most earthquakes along transform plate boundaries tend to occur at shallow to moderate depths in the crust
  14. explain convergent seismicity:
    steep diping plane called wadati benioff zone
  15. explain divergent seismicity:
    • transform fault- strike slip faulting
    • divergent boundary-normal fault
    • shallow low magnitude earthquakes
  16. what are difference between body waves and surface waves?
    • body waves move through interior of the earth
    • surface waves confined to earth crust
  17. what are the two body waves and explain
    • p wave-fast
    • go through solid and liquid
    • pushes and pulls
    • s wave- second fastest
    • go through solid
    • side to side
  18. what are the two surface waves and explain
    • rayleigh wave- third fastest
    • go through earth surface
    • move up, down, forward and back
    • love wave-slowest
    • go through earth surface
    • move side to side
  19. which type of waves do liquids absorb
    S waves
  20. wht is a seismogram made by?
  21. what are the order of the waves ?
    • p wave
    • s-p interval
    • s wave
    • surface wave is last
  22. what are seismometers?
    measure and help locate earthquakes
  23. how do geologists determine richter magnitude of earthquakes?
    • measure amplitude of largest wave
    • time interval b/w P and S wave
    • plot two measurement on graph and connect points
  24. what is the study of seismic waves in order to improve understanding of earths interior?
  25. wave refraction is used to identify a _________
  26. seismic data confirm the existence of _________ in the earths interior
  27. what is a mohorovicic discontinuity?
    about 8 km beneath ocean basin and 20-70 km beneath continents
  28. what uses seismic data to make cross sections of earth interior?
    seismic tomography
Card Set
chapter 12