Student Name ___________________
Salt Lake Community College - Geography 1700 – Natural Hazards
Mid-Term Exam, Fall 2012
A. J. Allred, Adjunct Instructor
NOTE: Based on class discussion, this version will contain some wording changes. Questions
#17, #24 and #38 were changed slightly to improve understanding of the issue. Some of these questions, in
one form or another, may appear on the final exam.
1. For earthquake damage to occur, the hypocenter should be located about how far to one side, rather than
directly below the epicenter?
a. Hypocenter at least 50 miles away from the epicenter, in order to provide timing space between P
and S waves
b. At least 100 miles away, for the same reason as above
c. At least 50 miles away from the epicenter, with P and S wave timing being important only for
measuring distance to the quake, not quake damage
d. For damage to occur at all, a quake epicenter cannot be more than five miles from the hypocenter
e. All of the answers above are irrelevant, and the question itself is in error.
From page 54, by definition the epicenter is directly above the hypocenter, so it could never be
anywhere else.
2. An earthquake of M 9.1 will cause about how much more ground motion or shaking than a quake of 9.0?
a. 1,000 times more ground motion
b. 10 percent more shaking
c. A multiple of about 32 times
d. About 30 percent more ground motion
e. None of the above is a good estimate
(see Table 3.3 on page 55 . . . 0.1 change in magnitude = 1.3 change in ground motion)
3. In the absence of an officially approved run-up map, what is a reasonable personal guideline for designing
your own safe zone during a tsunami warning? How far would you want to go to feel safe?
a. 1,000 feet horizontally or 1.2 miles vertically
b. Some combination of at least 5,000 feet horizontally and/or at least100 feet vertically
c. At least 1.2 miles vertically and 1.2 miles horizontally
d. It is bad advice to try to make your own estimate of inundation distance or elevation
e. Observe the beach as the wave arrives, and then form a plan for evacuation distance
4. An earthquake in California (at the ocean) can kill people in Italy more than 5,000 miles away. The reverse
is also true.
True ___
False _X__
Many maps in the textbook show that Italy and California are separated by continental masses that a
tsunami wave cannot cross.
5. Earthquakes of the “slip-strike” variety are not responsible for the Wasatch Mountains that have been rising
above Salt Lake valley.
True _X__
False ___
page 58, column 1.
6. As nations gain technology and financial wealth, natural hazards that once caused disasters now may
produce catastrophes. (from pages such as 15, 20, 22 and 77, and class discussion and related references in
most chapters of the book. Technology, especially regarding energy and transportation, allows people to
live in places and alter landscapes in ways that sometimes create hazards or make them worse. Often,
technology, including social technology, such as insurance and other government interventions, can
contribute to human activities that can worsen hazards. Page 236 illustrates the tendency for people to not
heed available information).
True _X__
False ___
7. Due to gradually improving land use planning and hazard insurance, the number of buildings on hazardous
sites is probably declining substantially. (See page 20. Also, every chapter of the book makes reference to
the role of land use planning as a countervailing force to general urban expansion. Land use plans are weak,
out-of-date or non-existent for many places in the world, and are not fully implemented or enforced in even
many communities with otherwise strong land use planning processes. Each chapter also has references to
the general effect of sensitive lands being crowded with human population, constraining options for hazard
avoidance).
True ___
False _X__
8. Expanding urban development is probably increasing the overall risk of floods in Salt Lake valley.
True _X__
False ___
Population growth in Salt Lake valley has gradually encroached on sensitive lands that were avoided
until more suitable sites have been taken. These include steep hillsides, stream floodways and unstable
soils. Hard-surfacing, especially on slopes, results in rapid run-off and a tendency for small floods to
become large floods. See also page 236 for discussion on effects of concentrated urban development.
9. Millions of people have lived successfully in caves made of fine-grain silt (as long as it does not rain and
quake at the same time). One reason why catastrophic events occur is the history of success, and
complacency, experienced by generations of people who have lived in places that are subject to long-period
events, such as coincidence of heavy precipitation and seismic events that may not occur together for
hundreds, or even thousands of years. See page 16 for “Magnitude-Frequency” concept).
True _X__
False ___
10. People often build in flood hazard areas because river shorelines fail to provide clues about where the river
will go during high-flow events.
True ___
False _X__
Column 2 of page 184 is one of many textbook references to human interaction with flooding. Not only are
hazard maps increasingly available and accurate, floodways, riparian habitat, swamps, meadows, bogs, meander
scars, historical records, soil types and a host of other evidence can help identify areas prone to water
inundation. Still, it is important to note that land use planning, regulation and the science of hydrology have
much to learn about water flows. Hazards still abound, for lack of full understanding and/or full willingness to
use good judgment. Page 172 provides one of many examples where “nature” provided information that was
missed or ignored.
11. In spite of the fact that most dams in the United States are on public land and subject to regular maintenance
and inspection, dam-related earth failures and flooding are still common.
True ___
False _X__
Most dams and levees are on private property, not public. Yes, failures due to lack of maintenance and
inspection are common. See Page 191.
12. River levees are controversial because they are very reliable but generally too expensive for property
owners and communities who need them.
True ___
False _X__
(See pages 191, 195 and elsewhere. Levees are controversial not because they are too expensive, but because
they not only fail sometimes, but sometimes create worsened conditions either upstream or downstream even
when they work properly for the locations they were intended to protect. In some cases, high cost for levee
maintenance is yet a further problem.
13. Theories about human-caused global warming and natural hazards are difficult to evaluate because the Earth
shows a geologic record of warming and cooling itself over and over regardless of human activity.
True _X__
False ___
(See Chapter One)
14. The daily weather forecast is often a vital tool for predicting soil failure.
True _X__
False ___
Class discussion heavily emphasizes that the presence of water is a huge factor in whether or not soils will be
stable or not. Column 1 of page 175 is one of many references in the textbook that address this issue. Almost
every page of Chapter 7 mentions the role of water in earth stability. See also Page 208 for the association
between precipitation and soil instability. See also page 233.
15. The maximum safe angle of repose is directly and positively correlated to the amount of water in the sloped
land form.
True ___
False _X__
Similar concept involved with Question 14 above. An INVERSE relationship means that as one factor goes up,
the other goes down. In this case, the MORE water, then LESS slope stability. Water is a lubricant that reduces
the friction or “stickiness” of earth material, allowing it to flow, fall or otherwise move more easily. See also
pages 211 and 213.
16. To turn an earth flow into a slump or creep, just add more water.
True ___
False _X__
An earth “flow” is faster and more liquid than slower, more viscous processes such as creep and slump. Adding
water will increase the chance of “flow”. See pages 217 and 231 as well.
17. According to the class textbook, during the past 25 years, about how many people are believed to have died
from direct effects of California earthquakes? (See Table 3.1 on Page 53)
a. Probably about 65 130 (revised – still an estimate, see Table
b. 527 from direct effects, more than 1,000 due to documented secondary effects
c. More than 1,000, from all quake-related causes
d. Documented deaths exceed 5,000, from 1985 through 2010
e. The class textbook does not provide any totals or estimates for recent California quake deaths
As described in the textbook, two large quakes in California each killed about 60 people each. Smaller quakes
killed either no one or just a few people. As per class discussion, major natural disasters also caused residual
deaths that accumulate over time after the main event. Such deaths are seldom reported. Answer ‘a’ is easily
the best, although for clarity the number shown for this answer is increased to more than 100.
18. Which of the following quake-related energy waves typically causes the most damage to buildings?
a. “S” waves
b. “P” waves
c. The point where “S” and “P” waves meet each other
d. Surface waves
e. Sound waves (sonic shock)
See page 61. It is important to understand that energy waves must reach the location of buildings, people and
surface topography in order to have an effect.
19. Because of the Modified Mercalli earthquake measurement system, scientists tend to rely on quake
‘foreshocks’ for promoting community warning systems.
True ___
False _X__
Foreshocks often occur, but it is difficult or impossible to know which tremor is a foreshock or main shock.
See page 83. See colum 2 on page 68 as well.
20. In general, earthquake shaking at any location will tend to vary negatively (inversely) with the time
difference between arrival of P and S waves.
True _X__
False ___
P 61-63. Increasing time between arrival of P and S waves is directly related to distance back to the source.
Increasing distance is directly related to attenuation of quake energy. The further you are from a quake the less
you will feel it, given that other factors remain equal.
21. In Utah, the risk of financial loss due to earthquakes is relatively higher than in the eastern United States
because of our local reliance on lightweight wood-frame houses rather than stone or brick.
True ___
False _X__
Clearly, quake hazards are more widespread in U.S. western states, including massive subduction zones located
along the U.S. portion of the “Ring of Fire.” However, the prevalence of wooden and steel-frame buildings
in newer western cities does not create a greater hazard than older buildings in older communities in eastern
states that often constructed of heavy, unreinforced masonry.
22. Most people who die in floods are in unstable small water craft, such as kayaks, canoes and personal
flotation devices.
True ___
False _X__
See column 2 on page 177.
23. The term “flood stage” is just a term that people use when they made the mistake of leaving valuable
property in the wrong place. Page 176 1st col.
True _X__
False ___
24. After more than 100 years of “channelizing” rivers and streams, we U.S. society may have learned that
letting surflace flows do what they want is probably less expensive, safer, and much better for the natural
environment. Pages 191-196. Although the textbook does not draw a definitive conclusion, the facts and
trends presented, combined with the teacher’s professional experience, suggest that this question is more
true than false. A host of other places in the textbook strongly support the concept of minimizing disruption
of natural processes that involve water movement. Note: For clarity, the word “we” was replaced by “U.S.
society”
True _X__
False ___
25. Some of the “after-shocks” from the 2011 earthquake near Japan were more powerful than any earthquake
ever recorded in Utah.
True _X__
False ___
News reports cited in class report after-shocks from quakes with M>8.0 as often exceeding the largest quake in
recorded Utah history. Page 93 explains the magnitudes of aftershocks as being, by definition, lesser than main
shocks by a magnitude of at least 1.0. Utah’s largest measured quake was about M=6.4. Page 69 indicates that
great quakes are usually associated with subduction zones along earth’s major plate boundaries, such as along
the Pacific coast rather than in Utah.
26. Flash floods and dam failures are most common in rainy climates, but can occasionally present significant
risk for death and injury in dry regions such as Utah.
True ___
False _X__
Dry country typically exhibits steep, hard-surface terrain that crumbles often and is not covered by vegetation
that can ease the effects of water. Hard surfaces in dry climates typically result in faster surface flows,
including flash floods that can overwhelm retention structures and catch people by surprise. Page 176 indicates
that flash floods are more common in dry country. Flood flashing is very common in Utah and surrounding
states where arid climate prevails.
27. Unlike most poor countries, in the United States electronic warning systems are an expensive but useful way
of preventing financial loss due to earthquakes.
True ___
False _X__
Warning systems alert people to move to safe position. Buildings and other assets are seldom moveable.
Financial losses are rising, while deaths are declining, in part due to better warnings.
28. Government-sponsored investigations have mapped underground hazards in areas where land development
is planned. Hazards include old mines, karst formations, expansive soils, fault lines and groundwater.
True ___
False _X__
Pages 91-93 include many references to “prospective” efforts that are underway or yet to occur. Until the work
is done, it is not done. Pages 91 and 227 are some of the many textbook examples showing that work is not
done.
29. Which of the following tools is best for identifying the location of an earthquake:
a. Attenuation
b. Triangulation (see Page 65)
c. Manipulation
d. Inoculation
e. Mastication
The entire textbook is based on the concept of prevention of hazards rather than clean-up afterward.
Food storage seldom saves lives. Building codes, when implemented, clearly save lives (see Page 91
and elsewhere). The difference in kill rates for similar earthquakes is a good example: Northridge and
Loma Prieta compared to Haiti. Pages 92and 93 illustrate planning and prevention.
30. High mountains near Salt Lake City are evidence of massive subduction zones that are typical of tectonic
plate boundaries.
True ___
False _X__
Page 74 illustrates intraplate boundaries for major quakes – Utah is not included. Class discussion on Figure
3.5 on page 58 described Utah as being near, but not within the most substantial part of the coastal Ring of Fire
and its subduction zones. As indicated in text, compare Utah to the most active portions of the Pacific Rim
shown in the map.
31. The continuing, long-term increase in U.S. natural hazard deaths is mostly a function of:
a. Rapidly rising U.S. population, especially illegal immigrants
b. Financial deficits that prevent rescue efforts and hazard mapping
c. Lack of good information about hazards and prevention
d. Increasing disposable income for purchasing expensive vehicles and other property at risk
e. Loss of life due to natural hazards is actually declining in the United States
(see Pages 3-6 in Chapter One. Class discussion and numerous tables and text in the textbook
illustrate that death rates are generally declining while financial losses are almost universally
rising. Answers “a” through “d” are valid factors for rising financial losses, but not for
explaining declines in loss of life).
32. As a general rule, the construction of dams and reservoirs will result in degraded ocean beaches along ocean
coastlines far away.
True _X__
False___
See pages 184 and 185, Figure 6.25 on page 188.
33. In total, the world’s massive ‘shield’ volcanoes present less overall hazard to people and property than do
smaller ‘composite’ and ‘dome’ volcanoes.
True ___
False_X__ (see page 131, column 2). Steep-sided volcanoes are much more
associated with viscous, gassy and explosive eruptions. Shield volcanoes are more typically mild in eruption,
often associated with surface flows of magmatic material, rather that ejections into the atmospheric. Composite
volcanoes are also more associated with the “Ring of Fire” along which occur many of the world’s most
explosive and hazardous eruptions occur. See pages 132-137 also.
34. Hard, dry clay can support heavy buildings, and is an exception to the general rule that size of earth particles
is directly related to soil stability.
True ___
False_X__(Class discussion emphasized that clay can be firm when dry, but may
be impossible to keep isolated from water. When wet, clay soils can expand in volume and become slippery
and completely unstable.)
35. In the United States, hazard insurance does not protect property and does not prevent loss of life caused by
natural hazards. Insurance policies are for replacing things that are lost or damaged. In fact, insurance may
provide a false sense of security, particularly when advertising materials promote visual association between
people being “protected” rather than replaced or compensated. See Chapter One, page 20.
True _X__
False___
36. Which factors below are most associated with magmatic conditions that are violent?
a. Low levels of gases, less silica, and much lower viscosity
b. Relatively high levels of gases and high-silicate rocks
c. High-viscosity surface flows of lava
d. High-silica rocks and high viscosity
e. All of the above are associated with explosive volcanoes rather than flood basalts
Pages 126-128 explain how silicates and gases affect the explosiveness of eruptions.
37. Widespread adoption of modern land use planning standards and building codes now accounts for hazards
and prevents dangerous conditions.
True ___
False _X__
(See background for questions 21, 28, 29, and 35. Throughout the textbook, and in class discussion, emphasis
has been placed on the fact that land use planning and construction standards are still evolving, are often in need
of update, and are based on science and historical records that are still evolving as well. Even in the best of
communities, implementation is imperfect and in constant need of update and review).
38. Snow avalanches and landslides have what things in common:
a. Steep slopes and known “chutes” or pathways
b. Water H2O (The term “water” can be misleading, if it is construed to mean liquid, rather than
any form, such as ice or snow, soil water, etc.)
c. Layers of material separated by planes or sheets that are easily sheared, broken or separated
d. They are often popular places for visiting or building structures
e. All of the above are true for both snow and dirt
39. Due to public and private investment, overall financial losses due to natural disasters are rising along while
death counts are in decline.
True _X__
False___
(See Chapter One. Clearly, financial losses are rising, while fewer people are dying. The single most important
reason why financial losses are rising is the overall rise in wealth and assets that are exposed to hazards. In fact,
people are attracted to amenities associated with places that are especially prone to hazards: slopes, sea shores,
the “Ring of Fire”, volcanic soils, etc.)
40. An effective network of alert sirens in Japan would have prevented financial loss and shutdown of nuclear
power facilities during the 2011 Fukushima earthquake.
True ___
False_X__
(Alerts can move people to safe locations, but financial assets, including nuclear reactors cannot move. As a
result, financial losses are increasing even as the number of deaths is in general decline. The Fukushima
nuclear reactors could not have been moved or adjusted in any useful way in the 2011 tsunami event.
Moreover, even wave barriers proved inadequate, based on unexpected earth subsidence due to the quake.)
41. Energy for setting-up natural hazards such as earthquakes and landslides comes from radioactive decay and
sunshine.
True _X__
False ___
Terrestrial heat, including magmatic or molten materials, are energized by decay of radioactive elements and
their isotopes deep within the earth. The result is tectonic force and natural hazards. Meanwhile, solar
energy is an even larger source of motion that affects climate, weather, erosion and other forces that produce
or affect natural hazards.
42. Volcanic eruptions in the past 40 years, such as Mount St. Helens, have not produced enough ash to alter
world weather patterns in any significant way.
True _X__
False ___
Unlike volcanoes such as Krakatau, Mazama and Tambora, that occurred hundreds or thousands of years ago,
more recent volcanoes such as Mount St. Helens did not result in discernible world-wide climate change.
43. Geothermal energy resources in the western United States are relatively abundant because much of recent
volcanic activity and the region’s dry, sunny climate.
True ___
False _X__(Class discussion emphasized the vital role played by water in
connecting magmatic heat to the surface where it can play a role in geothermal energy development.
Without water, geothermal resources are virtually non-existent. Class discussion also considered how
current dry weather has affected Yellowstone Park.)
44. Magmatic rock tends to melt when pressure is released or reduced as the magma nears the surface of the
Earth. (see page 126 for the asthenosphere and decompression melting)
True _X__
False ___
45. In Sumatra, planners do not expect small children to out run a tsunami. In the United States, planners store
flood water at elementary school grounds and public parks.
True _X__
False ___(class discussion based on National Geographic magazine and
commonly seen detention and retention basins in Salt Lake valley. Emergency response officials in
Indonesia have calculated that ‘great quakes’ associated tsunami waves are expected in the near future
and that shoreline inundation will likely proceed too quickly for many children to react successfully.
Meanwhile, in the Salt Lake area, and across the United States, flood management structures
frequently involve the use of public spaces, such as parks and school yards, for storing flood water.
46. During landslides, wet soils will convert into viscous gabions and bedding planes that slump downhill
toward the general angle-of-repose.
True ___
False _X__
Page 231- bedding planes are examples of weak places in earth formations; p 233 - gabions are structures built
by people. Gabions are not created by moving soil – they are one of many structures created by people to
help control or prevent soil movement.
47. Government programs offering “buy-outs” to property owners have not been very successfully in
convincing people to leave hazardous areas.
True _X__
False ___ (pages 144, 151, 156, and158 and class discussion all focus on factors
that deflect government efforts to achieve lasting resettlement. See also pages 199 and 201.)
48. Water that is disturbed by an earthquake will move at about what speed across open ocean?
a. 40 mph
b. 450 mph (see page 104)
c. 3.6 miles/sec
d. 1,000 mph
e. None of the above is a good estimate, because tsunami wave run-up velocity becomes measurable
as it nears the shoreline.
49. People will not build in areas that are prone to landslides if they are provided good quality information
about the risks involved. Page 236 column 1, page 229, column 2, page 231,
True ___
False _X__
50. Even though California is more prone to damaging earthquakes, an East Coast quake damaged the
Washington monument and U.S. capitol building in what year?
a. 1822
b. 1762
c. 1890
d. 1766
e. Last year (class discussion and references to general news media)