Salt Lake Community College - Geography 1700
Student Name: ____________________
Quiz #2
A. J. Allred, Adjunct
B.
*Note: You might notice that I have made wording changes to some of the quiz questions, based on how students
responded in class. I learn about you -- you learn about me.
1. In an earthquake, the epicenter is the most dangerous location in terms of shaking, ground displacement and
damage to buildings and facilities.
True ___
False _X__
It is true that energy dissipates or attenuates with distance away from the epicenter; however, consider that the
epicenter itself may be many miles above the hypocenter where energy was released.
Moreover, conditions surrounding the epicenter vary widely in how they react to quaking - hard rock, or mud, sand,
steep slopes, urban areas, tall buildings or structures made of wood, or places where no one lives. At the
epicenter itself there may be no people at all, or there may be tall buildings, open water, or empty desert.
The quality of building materials is a major factor by itself. Overall, there is no confident reason to conclude that the
epicenter itself will be more affected by an earthquake than surrounding areas.
2. Earthquake energy is released in various waves, the fastest of which are:
a. Primary
b. Secondary
c. Surface
d. Shear
e. Love
A “P” wave, or “primary” wave is compressional - - like shoving water with your hand - - the energy goes straight
out and away. As such, it travels faster than “secondary” or “S” waves that tend to move side to side as they
move outward from the hypocenter. A “P” wave is even many times faster than the speed of sound - - faster than
a speeding bullet.
Based on the book, I calculate that a “P” wave travels at more than 13,000 miles per hour. The speed of sound
(like thunder) moves at only about 750 miles per hour.
3. Human populations are growing in many of the world’s most earthquake-prone regions. To ensure continuing
public safety, building codes are up-to-date and land use planning prevents development in hazardous areas.
**Note: If any part of a test question is false, then the whole thing is false. The first statement above is TRUE - - but
the second part is true only in a few places around the world. Most places are not up-to-date. Even countries that are
wealthy and experienced with natural hazards, like Japan, have been caught by surprise by recent natural events - resulting in disasters. The United States is advanced, but still caught by surprise sometimes.
True ___
False _X__
4. An earthquake of M = 6 releases about how many times more energy than a quake of M = 4?
Multiply each increase in Magnitude by 32: 45 = 32 times more energy
5 6 = 32 times energy
So, 46 = 32 x 32 = 1,024 times more energy released
a. 2.0
b. 20.0
c. 100.0
d. 1,000.0
e. 33,000.0
5. A tsunami ‘run-up’ map shows how far away from shore a tsunami wave develops and how long it will take to
reach coastal cities.
True ___
False _X__
A ‘run-up’ map describes how a wave will act when it reaches the shore, showing what land areas will be
inundated. A ‘run-up’ is helpful for evacuation or planning for building construction and safety zones. Yes, the
run-up map is based on guessing what kind of tsunami waves to be expect, but the map is about what happens on
land, and has no way of predicting where a tsunami originates or how long it takes to arrive.
6. Inland urban centers like Salt Lake County are far enough away from the ocean to be safe from water waves that
may be provoked by earth movement.
True ___
False _X__
It is important for people in Utah to recognize that earthquakes are common in this region and that lakes and
reservoirs in mountainous country represent a real hazard for water waves during a seismic event. Dangerous
water waves have been caused by landslides and earthquakes that are not associated with under-sea earthquakes.
Even the Great Salt Lake could slosh or splash during a large quake. There is very little elevation between the
Great Salt Lake and downtown Salt Lake City. Even a small seiche wave could over-run the Salt Lake
International airport, both freeways, and major industrial areas.
7. To prevent earthquake damage from ground shaking, buildings should be as heavy and rigid (stiff) as possible.
True ___
False _X__
Heavy masonry can sometimes absorb a great deal of shock, but can also crumble or fracture easily when not
supported by flexible, shock-absorbing steel. In contrast, most modern buildings can flex a great deal, rather than
collapse. Likewise, heavy roof structures are common in many less-developed regions, leading to quick collapse
when earth moves.
8. The details of a local coastline, at a scale of just a few feet or yards, may be just as important for safety planning
as the size and activity of a nearby undersea continental subduction zone that produces ‘megathrust quakes.’
True _X__
False ___
Local conditions are hugely important when seismic waves come ashore. The shape of the beach, obstructions,
islands, time of day, weather conditions, the number of people and quality of buildings are vastly important in
determining what water waves will do at the shoreline. As well, the preparation of people for evacuation may be
the single most important controlling factor in many cases.
9. Compared to the outdated Richter scale, the modern Modified Mercalli method ensures a faster, more timely
measure of earthquake magnitude and damage outlook.
True ___
False _X__
The Mercalli method provides the best current overall assessment of an earthquake, including an accurate estimate
of magnitude; however, the results of Mercalli methodology takes time, sometimes weeks, in order to gather data
and compile results.
10. What level of change would a GPS or laser device show for a full year of seismic “creep” or continental drift at
many of the world’s great tectonic plate boundaries?
a.
b.
c.
d.
e.
0.4 inch
0.004 inch
40 feet
400 feet
4000 feet
Based on class discussion and facts in the book, many tectonic plates move enough each year to be measurable by
laser or GPS devices. As an example, the ‘rebound’ of the North American continent after the “Ice Age” and
general tectonic movement westward are both roughly ½ inch per year.
11. Solar energy plays an important role in plate tectonics and other movements of Earth’s crust, including
earthquakes. Conversely, shifting continental plates around the “Ring of Fire” can affect solar energy reaching
Earth.
True _X__
False ____
A foundation concept for Geog 1700 is that humans live at the interface between gigantic forces of nature – tectonics
below and solar from above. A massive volcanic eruption can eject enough dust into the atmosphere to block solar
energy that weather, or even climate, can change.
12. An earthquake warning system might be most useful if based on:
a. The magnitude of “S” waves
b. Electronic messaging based on the arrival of “P” waves
c. The time difference between the hypocenter and the epicenter
d. Surface waves
e. An alarm that is based on sound waves traveling through the air.
13. An event forecast will not usually include a date and time.
True _X__
False ___
Predictions are more specific than forecasts or outlooks, and often include date and time.
14. If a tsunami warning is issued for your location, which of the following practices is probably best:
a. Avoid panic and confusion by waiting for local officials to advise what action to take.
b. Invoke your own personal action plan for evacuation based on your own planning and personal fitness
c. Choose your action based on keeping a good view of the beach to verify tsunami behavior
d. Stock up on bottled water and secure your personal possessions until the alert is lifted
e. Maintain good public order by following the general flow of other people as they react to the news.
There is nothing wrong with avoiding panic and following official instructions. However, taking personal
responsibility is even better, because it would include knowing something about official notice and comparing
that to your own readiness to respond. In emergencies, public officials are often as surprised as the general public
- - sometimes official directions may be entirely absent. For tsunami country, being ready to move to higher
ground, in an orderly way, should be a pre-planned personal foundation.
15. The modern Modified Mercalli system for earthquake reporting is a good predictor of the size, number and timing
of tsunami waves.
True ____
False _X___
The Modified Mercalli system tells the story of an earthquake after the quake occurs. In order to be useful for
helping people escape tsunami waves, predictions must be made very quickly using instrument readings about general size
and location of the quake, and then comparing that information to pre-planned knowledge about the shoreline and how well
structures are ready for incoming water.
kes into account a variety of factors that help determine the true magnitude of an earthquake. Many of these factors are
found in the results of the quake: the size of cracks in the ground and buildings, how much damage occurred and where,
and even newspaper articles and interview with people nearby. That work takes time - So, Modified Mercalli ratings are slow to develop, but tell a more full and accurate story about the quake