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Geology 101 Earth & Environment – Spring 2017
Study Questions 3
Recommended:
Hand-write your answers to the following questions using your class
notes, text book, online readings, etc. For most people, hand-writing is
much better for memory than typing. Afterwards, be sure to doublecheck the accuracy of your answers.
Part 1 - Plate Tectonics
1. What is the hypothesis of continental drift? What was Pangea? What happened to
Pangea? What is some of the evidence for the idea that all of the continents were once
joined together.
2. Compare the theory of plate tectonics to the hypothesis of continental drift. Be sure to
include things that are part of plate tectonic theory but are absent from the earlier
continental drift hypothesis.
3. How are earthquakes important to our understanding of plate tectonics? How is the
magnetism recorded by rocks important to our understanding of plate tectonics?
4. What is the lithosphere? What parts/layers does the lithosphere include?
5. How is the asthenosphere different from the lithosphere? What property of the
asthenosphere is important to plate motions?
6. What is a tectonic plate? What features/evidence tell us where plate boundaries are
located?
7. Do the edges of the continents and oceans always coincide with plate boundaries? How
do "active" continental margins differ from "passive" continental margins?
8. What happens at divergent boundaries? Describe the two types of divergent plate
boundaries. Draw and label a sketch of at least one type of divergent boundary.
Include arrows in your sketch to show the direction of plate movement.
9. What happens at convergent boundaries? Describe the three types of convergent plate
boundaries. Draw and label a sketch of at least one type of convergent boundary.
Include arrows in your sketch to show the direction of plate movement.
10. What happens at transform boundaries?
11. How are transform and divergent boundaries connected?
12. Explain how plate tectonic processes can split apart a continent and form a new
ocean. Explain how an ocean can close up and have a mountain range form in its
place.
13. List the specific types of geologic structures (types of faults, types of folds) that can
occur at each type of plate boundary.
14. Describe how do oceanic and continental crust differ (include composition and
density). Which type of crust is formed through igneous processes (both intrusive and
extrusive) at divergent boundaries?
15. What is a hot spot? What is (or might be) a mantle plume?
16. What is the present (or past) plate tectonic setting that formed / caused each of the
following. If associated with a plate boundary, list the type of boundary. If associated
with a hot spot, list hot spot.
• Himalaya mountains
• Red Sea and East African Rift
• Hawaii and Yellowstone
• Andes mountains and the Cascade Range
• Aleutian Islands
• Mid-Atlantic Ridge, Juan de Fuca ridge, and East Pacific Rise
• San Andreas Fault
• 2011 Japan earthquake and tsunami, 2015 Chile earthquake and tsunami
• Appalachian Mountains
17. How can plate motions be measured over the long term (e.g. hundreds to thousands to
millions of years)?
18. How can plate motions be measured over the short term (i.e. modern-day
movements)?
19. What is some of the evidence for the existence of tectonic plates? What is some of the
evidence that they move? How do we know that the continents used to be in different
locations in the past?
20. What is convection, and how is it related to plate tectonics?
21. What is slab-pull? What is slab rollback? Why do these occur? How are they
important to plate tectonics?
22. Having multiple lines of evidence which agree with each other provides increased
confidence that a scientific explanation is correct. Using at least two examples,
explain how plate tectonics can be tested and confirmed by comparing different types
of evidence.
Part 2 - Introduction to Natural / Geologic Hazards
1. Why do we care about natural hazards?
2. Why is it important to reduce their impact?
3. What are some key steps can we take to reduce the impact of natural hazards, or at
least not let things get worse?
Part 3 - Faults, Folds, and Earthquakes
1. What is stress? What are the three kinds of stress? Which type of stress occurs at each
of the three types of plate boundaries?
2. What is strain? Describe each of the three main types of strain. Explain how pressure,
temperature, and rate of deformation determine the type of strain that happens.
3. How is a fold different from a fault? What type of strain do each of these represent?
4. Explain how you can identify and tell the difference between an anticline and a
syncline. Draw a sketch of each type of fold.
5. Explain how you can identify and tell the difference between normal, reverse, thrust,
and strike-slip faults. How can you tell the difference between right-lateral and leftlateral strike-slip movements? Draw and label a picture of each type of fault showing
the direction of movement and the direction of the stress that causes it.
6. Describe how the elastic rebound theory explains the way in which faults generate
earthquakes. Why does the name include "elastic" and "rebound"?
7. What are body waves? How do body waves and surface wave differ? Which type of
wave (body or surface) causes more damage during earthquakes?
8. How are P-waves and S-waves different? Be sure to include relative velocity, type of
movement, and the types of materials (solid, liquid, gas) through which they may
travel.
9. What is the difference between the epicenter and focus of an earthquake?
10. Explain how a seismograph recording can be used to determine how far away an
earthquake happened.
10. What is meant by the intensity of an earthquake? For a single earthquake, is intensity
(and amplitude) the same everywhere, or does it vary?
11. How is earthquake magnitude different from intensity? What information is needed to
calculate the magnitude of an earthquake?
12. Explain how the Richter scale for magnitude works. How much greater is the
amplitude of seismic waves for a magnitude 6 earthquake vs. a magnitude 5
earthquake? What is the difference in energy released? What about the difference
between a magnitude 6 and a magnitude 8 earthquake?
13. Which are more common, larger earthquakes (greater magnitude) or smaller
earthquakes (lesser magnitude)? About how many magnitude 2 earthquakes happen
every year? Do these cause any damage? Do people feel them? About how many
magnitude 9 earthquakes happen during an average 100-year period?
14. How does the amount of the fault that rupture (rupture area) affect the magnitude of
the resulting earthquake? How does the distance that the fault moves (displacement)
affect the magnitude of the resulting earthquake?
15. Which types of plate boundaries produce shallow earthquakes? What type of plate
boundary produces the deepest earthquakes and why? (This question combines
information from earthquakes and tectonics parts of class.)
16. Describe each of the following effects of earthquakes including what happens, what
areas are affected (and why), and whether each is a primary effect or a secondary
effect:
• shaking/vibrations/earthquake waves
• surface displacement
• liquefaction
• tsunami
• structural/building damage
• ground rupture
• fire
• landslides
17. How are the quality and type of building construction important to the risk of
earthquake damage?
18. Why is it important to take into account differences in the type of ground (e.g.
bedrock vs. soft sediments) when making earthquake hazard maps? What other
information is used to make earthquake hazard maps?
19. What types of information are used to predict the long-term earthquake risk for an
area?
20. What U.S. state has the most earthquakes? What type of plate boundary generates
many of these earthquakes?
21. Could an earthquake similar to the one that triggered the 2004 tsunami in the Indian
Ocean and the 2011 tsunami that devastated parts of Japan also occur on west coast of
the U.S.? Explain how we know.
22. Explain why the 8.3 magnitude earthquake in Chile this September killed only about
12 people, when many smaller earthquake in other places have killed people by the
thousands. What was done in Chile that saved so many lived?
23. Using the Japan earthquake and nuclear disaster as an example, explain the
importance of carefully considering natural hazards like earthquakes and tsunamis
when locating and designing critical facilities and infrastructure.
24. The mountains of the Basin and Range were formed by movement along what kind of
fault? What kind of kind of stress and movement caused the Basin and Range
mountains and valleys to form?
25. What kind of fault is the San Andreas? What kind of stress and movement caused the
San Andreas fault (and the related faults parallel to it) to form?
Part 4 - Discovering the Earth's Interior Layers
1. What is reflection? What is refraction?
2. Describe what has been learned about the interior of the Earth by measuring seismic
waves. Include each of the following:
• How thick is oceanic crust on average?
• How thick is continental crust, on average?
• Where is the thickest continental crust found? How thick is it?
• What layers of the earth can P-waves travel through?
• What layers can S-waves travel through?
• How and why do the velocities of seismic waves change with depth? What is the
Moho, and how is it recognized? Why is the asthenosphere also known as a low
velocity zone?
• What is an earthquake shadow zone? What happens at the boundary between the
mantle and outer core that causes the shadow zones? What do the shadow zones
tell us about the Earth's outer core?
• How have 3-dimensional images of mantle plumes been made?
• Draw and label a sketch of the interior of the earth showing the major layers.
Part 5 - Volcanoes and Volcanic Hazards
1. Explain the difference between effusive and pyroclastic volcanism. What factors
control whether an eruption will be effusive or pyroclastic?
2. Why are fractures, including columnar jointing, common in lava flows? How do they
form?
3. Why does mafic lava tend to spread out forming thinner, more extensive lava flows?
Why does felsic lava tend to form lava domes?
4. How are eruption columns/clouds and pyroclastic flows different?
5. What is tephra? How is it formed? List some of the different types/categories of tephra
particles.
6. Describe the major types of volcanic hazards. Be sure to include the following:
• How may lava flows be hazardous? Do lava flows often kill people? Why
or why not?
• How can pyroclastic eruptions be hazardous? What effects can they have
on people, machinery, transportation, etc.?
• What are lahars? How do they form? What areas around a volcano do they
affect? Does a volcano always have to erupt to produce a lahar?
• Which of the hazards discussed above can affect people the greatest
distance away from a volcano?
• Which of the hazards discussed above has the potential to kill the greatest
number of people? Why?
7. What is a shield volcano? Draw a sketch showing the shape that shield volcanoes
have. Why do they have this shape? What kind of lava builds shield volcanoes?
8. What is a stratovolcano (composite volcano)? Draw a sketch showing the shape that
stratovolcanoes have.Why do they have this shape? What kinds of eruptions build
stratovolcanoes?
9. What is a caldera? How does it form? How is a caldera different from a crater?
10. What kind of volcano is Mt. St. Helens? What kinds of activity and hazards has it
exhibited?
11. What is volcano monitoring? Describe two types of measurements can be made and
what these measurements tell us. Why is volcano monitoring important?
12. What types of information can be used to produce volcanic hazard maps? How can
such maps help save lives and reduce economic losses?
13. Who needs to be involved in reducing the potential for disasters caused by volcanic
eruptions?