Geology 110: Earth and Space Science
Chapter 5 (Earthquakes)
Homework
SELF-REFLECTION AND COMPREHENSION SURVEYS
Checkpoint 5.1, p. 115
#1: The map shows the locations of 15 of the world’s largest urban areas. Compare it
with a map of plate boundaries from Chapter 4. On the basis of their locations relative to
plate boundaries, which six cities are most likely to experience an earthquake?
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Your list of six cities:
Checkpoint 5.2, p. 115
#2: Using the map in Checkpoint 5.1, which of the groups of cities below are most likely to
experience subduction zone earthquakes?
a) Istanbul, Los Angeles, Sydney
c) Beijing, Tokyo, Calcutta
b) New York, Rio de Janeiro, Buenos Aires
d) Jakarta, Mexico City, Lima
Checkpoint 5.3, p. 115
#3: The discovery of the potential for mega-earthquakes on the Cascadia subduction zone is an
example of how scientific explanations are developed. Briefly explain how the development of
this hypothesis illustrated the following characteristics of scientific explanations.
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1. It was tentative.
2. It was based on observations.
3. It was predictable and testable.
4. It offered natural causes for natural events.
Checkpoint 5.5, p. 117
#4: An earthquake occurred on the Erie fault 5 kilometers beneath San Gabriel. Damage
from the earthquake was greatest in nearby Fremont. The farthest report of shaking was
recorded in Stockton. Where was the earthquake’s epicenter?
a. The Erie Fault b. San Gabriel c. Fremont d. Stockton
Checkpoint 5.6, p. 118
#5: Examine the following images.
Photo (a) was taken following the Izmit earthquake in Turkey in 1999. On the basis of
your observation of the picture, locate the approximate position of the fault (already
done; see red dots on photo) and classify the fault type. Cite the reasons and inferences
supporting your answer.
Photo (b) was taken in the Grand Teton mountain range of northwestern Wyoming.
Which location represents a fault scarp in the picture? a) 1 b) 2 c) 3 d) 4
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Checkpoint 5.9, p. 126
#6:
Examine the following cutaway view of a section of Earth’s crust containing a fault.
Answer the questions that follow, assuming that an earthquake originated at the focus
shown on the fault surface.
Which location represents the epicenter of this earthquake?
a) A and B only
b) C & D only
c) E only
d) none of these locations
Checkpoint 5.10, p. 126
#7: Examine the following seismogram, which shows a 26-minute-long record of the
seismic waves from the 1906 San Francisco earthquake as received by a seismograph
station in Germany, over 14,000 kilometers (8,700 miles) away. Then answer the
questions that follow.
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Which letter represents the arrival of the first S waves?
a) a
b) b
c) c
d) d
e) e
f) f
Approximately how much time elapsed between the arrival of the first P and S waves?
a) 60 seconds
b) 4 minutes
c) 10 minutes
d) 60 minutes
Checkpoint 5.13, p. 129
#8:How much would ground motion (amplitude) increase between magnitude 4.5 and 5.5
earthquakes?
a) No increase
c) 10 times as much
b) 5 times as much
d) 30 times as much
Checkpoint 5.14, p. 130
#9: Three sites (L1, L2, L3) record earthquake magnitude and earthquake intensity for the
same earthquake. L1 is located closest to the focus and L3 is farthest away. Where is the
intensity greatest and what happens to the earthquake magnitude calculated at the
different sites?
a) Intensity is greatest at L1; calculated magnitude is the same at each site.
b) Intensity is greatest at L3; calculated magnitude is the same for each site.
c) Intensity is greatest at L1; calculated magnitude decreases with distance from the
focus.
d) Intensity is greatest at L3; calculated magnitude decreases with distance from the
focus.
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Checkpoint 5.17, p. 134
#10:Analyze the Community Internet Intensity Maps for the Northridge and Whittier
Narrows earthquakes in Figure 5.20 and Checkpoint 5.16 and the Modified Mercalli scale
in Table 5.2. Determine approximately how far from the epicenter ground shaking would
have been strong enough to make it difficult for people to stand through both
earthquakes. (Note the scale in each map; also, intensities of VI or greater are difficult to
stand through).
Checkpoint 5.20, pp. 140-141: Earthquake Risk Rubric Exercise (NOTE: THIS
QUESTION SHOULD BE DONE WITH ALL THE INPUT YOU CAN GET
FROM CLASSMATES!
#11:This exercise requires that you consider what combinations of factors is most likely
to contribute to the greatest risk of damage from a future earthquake.
After graduation, you get a job working for a county planning task force in California.
The task force must examine the setting of several different cities and identify which is at
greatest risk for future earthquake damage caused by movement on known faults.
Your assignment is to fill out the evaluation rubric provided here by identifying factors
that would influence the risk of damage from a future earthquake. The location that
scores the highest on your scoring rubric will receive additional county funds to protect
key structures from earthquake damage. The factors you identify may be either physical
(such as nature of the local geology) or cultural (such as size of population centers).
Audience: You will create a scoring scheme that can be applied by the most educated (on
this topic) citizens. Specifically, you may consider that you are writing for city council
members or a concerned citizens group.
Main point and purpose: To demonstrate your understanding of the principal factors
that result in damage or loss of life from an earthquake.
Pattern and procedures: You must identify 4 factors and differentiate among
characteristics that make them high-, moderate-, or low-risk phenomena. One factor, the
proximity of the site to a fault, is included as an example (see accompanying table). If the
fault were to move in the future, sites closest to the fault would suffer the most damage
(high risk), whereas those farther away may experience little or no damage (low risk).
Each site with a high-risk factor is scored as 3 points; moderate-risk factors rate 2 points;
and low-risk factors rate 1 point. The site with the highest cumulative score for all factors
is at greatest risk from a future earthquake.
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Standards and criteria: You will be assessed on your choice of:
i. Relevant factors that would contribute to the potential for earthquake-related
damages;
ii. Identification of what constitutes high-, moderate-, or low-risk situations for each
factor;
iii. One factor as most significant;
iv. The applicability of your rubric to 4 sites in an idealized county in California.
Factors
Low risk
(1 point)
Moderate risk
(2 points)
High risk
(3 points)
close
Proximity to fault
moderate
(25-50 km)
far
(>50 km)
<25 km
<
(<25 km)
What is the most important factor in your rubric? Distinguish which factor is the
most significant under the circumstances of the exercise. The score for this factor will be
doubled. Discuss your justification for choosing the particular factor.
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Use your rubric in a hypothetical situation. Examine the information on the geology and
characteristics of 4 cities shown on the following map and rank them in order of greatest
to least risk of damage from a future earthquake.
Rank:
1.
2.
3.
4.
Checkpoint 5.12
12. Place the numbers corresponding to the following phrases in the appropriate locations
in the seismic wave Venn diagram (see page 128 for diagram).
1. Most damaging
2. First arrival
3. Last arrival
4. Body wave
5. Rayleigh wave
6. 4-6 km/s in crust
7. Second arrival
8. Love wave
9. 2-3 km/s in crust
10. In Earth’s interior
11. On Earth’s surface
12. Determines magnitude
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