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Geol 15 Mid Term II
200 points
Name: _____________________________________ Date: __________________
.1. (10 pts) You found some sandy sediment in a core collected along Humboldt Bay. The sandy
sediment is deposited above an organic peat layer and deposited underneath some muddy
sediment.
(a) what do you think is responsible for the deposition of that sand?
tsunami
(b) why do you think this?
Humboldt Bay is near the Cascadia subduction zone, capable of generating tsunami
The mud overlying the peat may represent coseismic subsidence
(c) how would you test your hypothesis?
I would look for beach/ocean diatoms in the sand, high marsh or freshwater diatoms in the
peat, and subtidal or low marsh diatoms in the overlying mud.
.2. (4 pts) The difference in energy released from a Mw= 5.0 and a Mw= 6.0 earthquake is:
a. 3 times b. 10 times c. 33 times d. hard to say.
.3. (4 pts) During large subduction zone earthquakes, some areas go up and some areas go
down.
a. true b. false.
.4. (4 pts) Interseismic strain in a subduction zone looks like the drawing above.
a. true b. false
.5. (4 pts) The largest earthquake ever recorded in historic times was:
a) Alaska, March 27th, 1964.
b) Sonora, Mexico, May 3rd, 1887.
c) Mexico City, September 9th, 1985.
d) none of the above.
Geol 15 Mid Term II
200 points
The following questions refer to the plate
map of the Pacific Northwest shown on the
right: the Cascadia subduction zone. Double
lines indicate oceanic ridges, a single line
indicates strike-slip boundary, and a dashed
line indicates a subduction
At each plate boundary, draw the focal
mechanism that would be expected to occur
at that boundary. Assume upper hemisphere
projections for the “beach balls”.
.6. (4 pts) Which boundary is convergent?
a. A b. B c. C d. D e. E
.7. (4 pts) Which boundary is a transform
fault?
a. A b. B c. C d. F e. E
.8. (4 pts) Which are divergent boundaries?
a. D, C, E
b. A, G, D
c. A, B
.9. (4 pts) Oceanic ridges are compressive boundaries. a. True b. False
.10. (4 pts) Where would you expect to see new oceanic crust being formed?
a. C b. E c. G d. all of these locations
e. none of these locations.
.11. (4 pts) Where would you expect to see oceanic crust being "consumed"?
a. A b. F c. E d. none of these locations.
.12. (4 pts) Where would you expect to see high heat flow?
a. A
b. B c. C d. none of these e. Both A and B
.13. (4 pts) The motion on the fault labeled C is: B
Geol 15 Mid Term II
200 points
.14. (4 pts) How do geologists know about the inside of the Earth?
A) They have drilled holes into the Earth and sent sensors down to its center
B) They study very large canyons that have been uplifted from the center of the Earth
C) They study the movement of earthquake waves throughout the Earth
D) They study the movement of water waves in the ocean
E) They have built a ship that can dig into the Earth and take a team of scientists to its
center
.15. (4 pts) Which of the following statements is false about P-waves?
A) P-waves are the fastest of the waves.
B) P-waves can move through solid, liquids, or gasses.
C) P-waves move with a push/pull motion.
D) P-waves cause the most damage in an earthquake.
E) All of the above statements about P-waves are true.
.16. (4 pts) Which wave is the last to reach the seismograph station?
A) P-waves
B) S-waves
C) Surface waves
D) Body waves
E) All of the waves reach the station at the same time
.17. (4 pts) Which wave produces the smallest amplitude?
A) P-waves
B) S-waves
C) Surface waves
D) Body waves
E) All of the waves have the same magnitude
.18. (4 pts) The distance to the epicenter of an earthquake is found ________
A) by locating the area where most of damage is centered.
B) by comparing the arrival times of the S-and P-waves.
C) by comparing the magnitudes at different locations.
D) by measuring the frequencies of waves at different stations.
E) by watching to see where the tsunami forms.
Geol 15 Mid Term II
200 points
.19. (4 pts) Which of the following is true about seismographs taken far from the epicenter of
the earthquake as compared to those that are closer?
A) There will not be any P-waves detected
B) There will not be any S-waves detected
C) The P and S waves will be closer together
D) The P and S waves will be further apart
E) The amplitude of the waves will be larger
.20. (4 pts) Mexico City was built on mud deposits. How will this affect the earthquake hazard
there?
A) Earthquakes will be dampened there
B) There will not be any earthquakes there
C) Earthquakes shaking will be increased
D) P waves will be seen, but not S waves
E) There will be more earthquakes, but they won't travel far
.21. (4 pts) The _________ waves' motion is similar to S waves, except it is from side-to-side in a
horizontal plane roughly parallel to the Earth's surface.
A. Rayleigh
B. PC. Love
.22. (4 pts) The ________ waves advance in a backward-rotating, elliptical motion.
A. SB. PC. Love
D. Rayleigh
E. None of these are correct.
Geol 15 Mid Term II
200 points
.23. (4 pts) The above record is called a______________.
a. sonogram b seismoscope c. seismogram d. marigram
.24. (4 pts) The arrival order of waves in above figure labeled A, B, C are:
a. S, P, L
b. P, L, S
c. L, S, P
d. P, S, L
.25. (4 pts) The subjective scale of intensity used most often to show areas of equal shaking is
called the _____________ Scale.
a. Richter
b. Slater
c. McGuire d. Modified Mercalli
.26. (4 pts) In the
Figure to the right,
where would you
expect the worst
shaking to occur?
a. A b. B
c. C
d. D
.27. (4 pts) In the same Figure, where would you expect the least shaking to occur?
a. A b. B c. C
d. D
Geol 15 Mid Term II
200 points
.28. (4 pts) A body wave that will not travel through a liquid is a ____________.
a. Gravity wave
b. P wave
c. S wave
d. none of these is correct
.29. (4 pts) The waves or wave that just runs along the surface are/is ___________.
a. Magnetic wave
b. Rayleigh wave
c. P and S waves
d. Love and Rayleigh
.30. (4 pts) The ray labeled A in the figure to
the right is a _________ray.
a. reflected b. deflected
c. defracted d. none of the above
.31. (4 pts) The ray labeled B in the figure to
the right is a ________ ray.
a. reflected b. refracted
c. defracted d. none of the above
.32. (4 pts) Total destruction (highest rating) of a populated area from an earthquake would be
given which rating on the Modified Mercalli scale?
a. XVII b. XX
c. XII
d. XIIII
.33. (4 pts) Earthquakes in the central and eastern part of the United States can be destructive
over much larger areas than the same size quake in the western United States.
a. True
b. False
.34. (4 pts) What is the difference between earthquake Intensity and Magnitude?
A) Only strong earthquakes have intensity
B) Intensity refers to the effects that earthquakes have, Magnitude refers to energy
released
C) Intensity cannot be measured, but Magnitude can
D) Intensity refers to energy released and magnitude refers to energy released
E) Only weak earthquakes have intensity
Geol 15 Mid Term II
200 points
.35. (4 pts) The point labeled A in the Figure to the
right is ____________ .
a. the locus b. the epicenter
c. the hypocenter
d. a fault scarp
.36. (4 pts) The point labeled B in the Figure to the
right is the ____________.
a. hexocenter
b. omnicenter
c. epicenter d. none of the above
.37. (4 pts) C in the Figure to the right is the
________________.
a. hypocenter b. omnicenter
c. fault scarp d. none of these
.38. (4 pts) Which wave is the last to reach the seismograph station?
A) P-waves
B) S-waves
C) Surface waves
D) Body waves
E) All of the waves reach the station at the same time
.39. (4 pts) Which wave produces the smallest amplitude?
A) P-waves
B) S-waves
C) Surface waves
D) Body waves
E) All of the waves have the same magnitude
.40. (4 pts) Which of the following is true about seismographs taken far from the epicenter of
the earthquake as compared to those that are closer?
A) There will not be any P-waves detected
B) There will not be any S-waves detected
C) The P and S waves will be closer together
D) The P and S waves will be further apart FREE
E) The amplitude of the waves will be larger
Geol 15 Mid Term II
200 points
.41. (4 pts) The amount of shaking that is felt from an earthquake depends on ________
A) location with respect to the epicenter.
B) depth of focus.
C) direction of the epicenter.
D) earth materials through which the waves move.
E) All of the above.
.42. (4 pts) Mexico City was built on mud deposits. How will this affect the earthquake hazard
there?
A) Earthquakes will be dampened there
B) There will not be any earthquakes there
C) Earthquakes shaking will be increased freebie
D) P waves will be seen, but not S waves
E) There will be more earthquakes, but they won't travel far
.43. (4 pts) The _________ waves' motion is similar to S waves, except it is from side-to-side in a
horizontal plane roughly parallel to the Earth's surface.
A. Rayleigh
B. PC. Love freebie
The following 3 questions refer to the plot on the
right:
.44. (5 pts) The “A” profile represents:
A. P-wave velocity
B. S-wave velocity
C. Love-wave velocity
D. Raleigh-wave velocity
.45. (5 pts) The “B” profile represents:
A. P-wave velocity
B. S-wave velocity
C. Love-wave velocity
D. Raleigh-wave velocity
.46. (5 pts) The “A” profile gives us evidence that:
A. The mantle is liquid
B. The outer core is liquid
C. The inner core is liquid
Geol 15 Mid Term II
200 points
.47. (7 pts) How many earthquakes are recorded in the plot to
the right?
A. 2 earthquakes
B. 3 earthquakes
C. 4 earthquakes
D. Not enough information to tell