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Volcanoes Activity
Objective
In this activity, we are going to explore the two main volcano types: shield and composite. We will
understand their connection to plate tectonics and learn more about hazards associated with each
volcano type.
Part 1: Volcanoes & Volcano Types
Go to http://nationalgeographic.org/encyclopedia/magma/ and look at the first 3 pictures
1. What is magma?
2. What is the difference between magma and lava?
3. Where is magma formed?
4. In which three locations does magma “well up”?
Read P. 202-203 in your textbook and answer the following questions
5. Describe the shape of a shield volcano
6. What is its general eruption style?
7. Describe the shape of a composite volcano
8. What is its general eruption style?
9. Make a sketch of each volcano below
Shield
Composite
Part 2: Where Are Volcanoes Located?
1. Look at the map given below. Are most of the world’s volcanoes located along a plate boundary?
Yes
No
2. Using your knowledge of plate tectonics (or the chart on P. 179), state whether or not the following
plate boundary types have volcanoes:
A.
Divergent plate boundaries
Yes
No
B.
Continental-continental convergent plate boundaries
Yes
No
C.
Continental-oceanic convergent plate boundaries
Yes
No
D.
Oceanic-oceanic convergent plate boundaries
Yes
No
E.
Transform plate boundaries
Yes
No
3. Most volcanoes are at subduction boundaries, but subduction is not necessary to create a volcano.
Which plate boundary has volcanoes but not subduction? ______________________________________________
4. In this lab, we are focussing on shield and composite volcanoes, but lava does erupt at divergent plate
boundaries as well. Visit http://www.geology.sdsu.edu/how_volcanoes_work/seafloorvol_page.html
and answer the questions below
A.
What feature is created at divergent plate boundaries? (Circle one)
Ridges
Trenches
B.
How does that feature form?
C.
What type of eruption is usually seen at divergent boundaries?
D.
Are these violent or gentle eruptions?
5. There are clusters of volcanoes on the map not located near a plate boundary (ex. Hawaii). What are
these volcanoes called?
6. Watch https://www.youtube.com/watch?v=jG-Sy0y08GM and explain how hot spots form.
Part 3: Volcano Shape & Eruption Style
Go to http://discoverykids.com/games/volcano-explorer/ to build your own volcano. Summarize what
happens when you change the silica and gas concentrations in the magma and describe the type of volcano
that forms, the type of eruption created and any hazards in the chart below
Silica Content
(high or low)
Gas Content (high
or low)
High
High
High
Low
Low
Low
Low
High
Type of eruption
(explosive, effusive, etc.)
Hazards
(list all shown)
Type of
Volcano
1. Which factor had more of an effect on the type of volcano formed: silica content or gas content?
2. Which conditions are required for the most explosive types of eruptions?
3. Watch https://www.youtube.com/watch?v=EGK1KkLjdQY and answer the following questions
A. Name the three types of rock and briefly explain how each are formed:
B. Which type would you expect to find at volcanoes? Why?
C. Explain how sedimentary and metamorphic rocks could become igneous rocks
4. We are going to focus on 3 types of igneous rocks: felsic, intermediate and mafic (not ultramafic).
Use the graph below to figure out which type has the most silica. The type with the most silica is
called ________________________________
5. Rocks with more silica are more viscous. What is viscosity?
6. Which is more viscous: water or molasses? _________________________________
7. Watch this video of the eruption of Kilauea, the currently active volcano in Hawaii:
https://www.youtube.com/watch?v=90XFpu-65JY
A. Would you describe the lava as having high or low viscosity? ______________________________
B. What does this tell you about the silica content of this lava?
8. Watch this video of the eruption of Mt. St. Helens: https://www.youtube.com/watch?v=H_HZVY1tT4
A. Does the Mt. St. Helens eruption in 1980 seem to have a high or a low viscosity? ____________________
B. What does this tell you about the silica and gas content of the magma?
9. Do you think rocks with high silica content produce more explosive or less explosive eruptions?
Why?
10. Would a violent eruption cause a tall and steep volcano or one with gentle slopes?
11. In general, continental crust is made up of more silica-rich rocks and oceanic crust is made up of
mafic-rich rocks. How explosive do you think volcanoes at the following settings would be?
A. Continental-oceanic convergence
B. A hot spot underneath continental crust
C. A hot spot underneath oceanic crust
D. Diverging oceanic plates
12. Complete the table below:
Composition Name
Silica Content
(high, intermediate
or low?)
Viscosity (high,
intermediate or
low?)
Eruption (violent
or gentle?)
Crust type (oceanic
or continental?)
Felsic
Intermediate
Mafic
Part 4: Exploring Volcanic Hazards
Watch this video about pyroclastic flows: http://www.discovery.com/tv-shows/discoverypresents/videos/ultimate-guide-to-volcanoes-pyroclastic-flow/
1. Is this hazard associated with more violent or gentle eruptions?
2. Does this type of hazard seem to have a high or low viscosity?
3. Would you expect to see felsic or mafic rocks?
4. At which type of volcano would you expect to see a pyroclastic flow, shield or composite?
Watch this video about lava flows:
http://www.discovery.com/tv-shows/discovery-presents/videos/understanding-volcanoes-lava-flow/
5. Is this hazard associated with more violent or gentle eruptions?
6. Does this type of hazard seem to have a high or low viscosity?
7. Would you expect to see felsic or mafic rocks?
8. At which type of volcano would you expect to see a lava flow, shield or composite?
*Note: lava flows are associated with both shield and composite volcanoes, but lava flows are the main
hazard at shield volcanoes
Watch this video about ash and the Mt. Pinatubo eruption:
http://www.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.lahar/mount-pinatubo-the-aftermathof-a-volcanic-eruption/
9. Is this hazard associated with violent or gentle eruptions?
10. Which rock do they mention in the video as “raining down”?
11. Does this type of hazard seem to have high or low viscosity?
12. Would you expect to see felsic or mafic rocks?
13. At which type of volcano would you expect to see pyroclastic flows and huge volumes of ash:
shield or composite?
Explore this page and watch the video about lahars: http://blogs.agu.org/landslideblog/the-raw-power-ofthe-lahar-a-volcanic-landslide-a-new-video-of-three-lahars-from-japan/
14. What is a lahar made of?
15. How fast can they travel?
16. Is this hazard associated with more violent or gentle eruptions?
17. Does this type of hazard seem to have a high or low viscosity?
18. Would you expect to see felsic or mafic rocks?
19. At which type of volcano would you expect to see lahars, shield or composite?
20. Out of all the hazards you’ve learned about, which hazards would you expect to see at Kilauea?
21. Out of all the hazards you’ve learned about, which hazards would you expect to see at Mt. Rainier?
Part 5: Case Studies
On the west coast of South America, the oceanic Nazca plate is colliding with the continental edge
of the South American plate.
Answer the following questions based on this information and what you have learned so far in this lab:
1. What type of plate boundary is this?
2. Would you expect to see subduction at this boundary?
Yes
No
3. Would you expect to see volcanoes at this boundary?
Yes
No
Felsic
Mafic
4. If so, what type of volcanoes?
5. Which igneous rocks would be present, felsic or mafic?
6. Would you expect a volcano in this location to have high or low viscosity? Why?
7. What hazards would you expect to see at this volcano?
8. Which of the two volcanoes below do you think you would find there?
A
B
Yellowstone National Park is located in Wyoming, Idaho and Montana.
Answer the following after reading http://www.yellowstonepark.com/how-the-yellowstone-calderaformed/
9. Is Yellowstone located near a plate boundary?
Yes
No
10. What is the term for the location of a volcano that is not on a plate boundary?
11. The Yellowstone hotspot is located under: (circle one) Oceanic Crust
Continental Crust
12. Therefore, the crust is: (circle one)
Felsic
Mafic
13. Yellowstone has had three major eruptions in the last 2 million years. The last eruption was
640,000 years ago and was 1,500 times larger than the one at Mt. St. Helens in 1980. What do you
think would happen if another large eruption occurred again soon?
At the very bottom of this website you will see a map showing the path of the Yellowstone hotspot. Use this
map to answer the questions below
https://volcanoes.usgs.gov/volcanoes/yellowstone/yellowstone_geo_hist_52.html
14. If the top of the map is north, where are the oldest volcanic eruptions from the Yellowstone
hotspot?
15. Where are the youngest eruptions?
16. What does this tell you about the direction of plate motion of the North American plate?
Part 6: Summary
Fill out the table below
Type of
Volcano
Shield
Composite
Plate Setting
(hot spot or
convergent)
Crust Type
(continental or
oceanic)
Magma
Composition
(felsic or mafic)
Igneous Rocks
Associated
with Each
Crust Type
Types of
Volcanic Hazards
(lava flows,
pyroclastic
flows, lahars, ash
fall, etc.)