Seismic Waves (PS3D) Quiz Key

Use this word bank to fill in the blanks

Mercalli Richter primary secondary twice
surface normal reverse strike/slip 100 times
compression transverse tension shear 10 times
  1.   reverse   compressive forces in the Earth's crust cause this fault.
  2.   compression   the type or category of wave that describes P-waves.
  3.   transverse   the type or category of wave that describes S-waves.
  4.   surface   earthquake wave that causes the most damage.
  5.   tension   a force on the Earth's surface that causes normal faults.
  6.   strike/slip   the type of fault that results from a shearing force.
  7.   secondary   second earthquake wave to arrive.
  8.   primary   first earthquake wave to arrive.
  9.   Richter   scale used to measure the magnitude of earth motion.
  10.   Mercalli   a scale used to compare damage caused by earthquakes.
  11.   10X   number of times stronger a Richter magnitude 6 earthquake is compared to a 5.
  12. Waves are defined as :
    a. wavelength times frequency. c. a rhythmic disturbance that carries energy.
    b. an up or down movement. d. particle movement over distance.
  13. The three seismic waves we studied are called:
    a. focus, epicenter and fault c. primary, secondary and shallow
    b. primary, secondary and aftershocks d. primary, secondary and surface
  14. Western Washington state has at _____ risk of a major earthquake.
    a. low c. great
    b. no d. 38%
  15. When stress in the Earth's crust causes a break in the Earth's crust, we call this:
    a. a fault. c. a landslide.
    b. a mountain range. d. none of these.
  16. The three main types of faults we studied are:
    a. normal, not normal, slip c. normal, reverse and strike/slip
    b. normal, reverse and shear d. forward, reverse and neutral
  17. The three main forces that act on a fault to cause its motion are:
    a. compression, tension and shear c. compression, convection and shear
    b. pressure, tension and slip d. pressure, lift and slip
  18. What causes the P-wave shadow zones? Use your r-words. 
    Refraction (bending) of the waves as they move through layers of different density and temperature.
  19. What information about the Earth's structure did the S-wave shadow zone provide us?  
    S-waves don't go through liquids. We learned that the outer core is liquid.
  20. In what two ways did we use earthquakes as tools for understanding plate tectonics?  
    The epicenters of the EQ were used to locate the plate boundaries. The path of a subducting plate was plotted by EQ. EQ provided a look into the hot (convecting) interior of the Earth.
  21. How would plotting earthquake depths have helped geophysicists when they were first trying to understand oceanic-continental convergent plate boundaries? Remember they didn't have the cross-section drawings of boundaries we have seen.  
    The EQ marked the path of the subducting plate.
  22. Would you expect deep focus earthquakes at a continental-continental convergent plate boundary? Explain your reasoning.  
    There are no subducting plates at a mature continental-continental boundary, so there should not be deep EQ.
  23. The video we watched about Pacific Northwest earthquakes said there were three locations for earthquakes here: subduction, deep focus (or Benioff) and crustal earthquakes. Draw our subduction zone cross-section diagram showing those locations.
  24.   44 s   S-P time
  25.   430 km   Distance
  26.   210 or 170 mm   Amplitude
  27.   6.8 or 6.7   Richter Magnitude


s-p distance graph richter nomogram