Seismic Waves (PS3D) Quiz Key
Use this word bank to fill in the blanks
- reverse compressive forces in the Earth's crust cause this fault.
- compression the type or category of wave that describes P-waves.
- transverse the type or category of wave that describes S-waves.
- surface earthquake wave that causes the most damage.
- tension a force on the Earth's surface that causes normal faults.
- strike/slip the type of fault that results from a shearing force.
- secondary second earthquake wave to arrive.
- primary first earthquake wave to arrive.
- Richter scale used to measure the magnitude of earth motion.
- Mercalli a scale used to compare damage caused by earthquakes.
- 10X number of times stronger a Richter magnitude 6 earthquake is compared to a 5.
- 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.
- 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
- Western Washington state has at _____ risk of a major earthquake.
a. low c. great b. no d. 38%
- 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.
- 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
- 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
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 44 s S-P time
- 430 km Distance
- 210 or 170 mm Amplitude
- 6.8 or 6.7 Richter Magnitude