1. Chapter 12

2. 1. Does increasing temperature increase or decrease viscosity of magma?
A. increase
B. decrease

3. 2. Does increasing silica content increase or decrease viscosity of magma?
A. increase
B. decrease

4. 3. Which magma type has the lowest viscosity?
A. felsic
B. intermediate
C. mafic

5. 4. Which magma type has the highest viscosity?
A. felsic
B. intermediate
C. mafic

6. 5. Which type of magma will produce the most explosive volcanic eruption?
A. cool and mafic
B. hot and mafic
C. cool and felsic
D. hot and felsic

7. 6. Which type of magma will produce the least explosive volcanic eruption?
A. cool and mafic
B. hot and mafic
C. cool and felsic
D. hot and felsic

8. 7. Are magmas feeding shield volcanoes mafic or felsic?
A. felsic
B. mafic

9. A. explosive B. non-explosive
8. Are shield volcanoes’ eruptions typically explosive or non-explosive?
A. explosive
B. non-explosive

10. 9. Stratovolcanoes tend to occur near what type of plate boundary?
A. divergent
B. convergent
C. transform

11. 10. Stratovolcanoes are typically fed by magmas of what composition?
A. felsic
B. intermediate
C. mafic

12. 11. What type of volcano is shown?
A. shield
B. stratovolcano
C. cinder cone

13. 12. What type of volcano is shown?
A. shield
B. stratovolcano
C. cinder cone

14. A. mid-ocean ridge B. island arc C. continental arc D. oceanic hotspot
13. Which volcanic environment will, on average, produce the most felsic lavas?
A. mid-ocean ridge
B. island arc
C. continental arc
D. oceanic hotspot

15. A. mid-ocean ridge B. island arc C. continental arc D. oceanic hotspot
14. Which volcanic environment is most likely to produce shield volcanoes?
A. mid-ocean ridge
B. island arc
C. continental arc
D. oceanic hotspot

16. 15. The Hawaiian hotspot track shows a change in Pacific plate motion at about 43 million years ago from to .
A. southward; southeastward
B. southeastward; southward
C. northwestward; northward
D. northward; northwestward

17. A. northwest B. northeast C. southwest D. southeast
16. Given the Yellowstone hotspot track, what is the direction of motion of the North American plate?
A. northwest
B. northeast
C. southwest
D. southeast

18. A. lava flows B. pyroclastic flows C. ash falls D. lahars
17. Which of the following results in the greatest number of fatalities?
A. lava flows
B. pyroclastic flows
C. ash falls
D. lahars

19. A. shield B. stratovolcano C. cinder cone
18. Which type of volcano represents the greatest hazard to people living nearby?
A. shield
B. stratovolcano
C. cinder cone

20. 19. What type of evidence is used to suggest explosive volcanic activity in the near future?
A. increased earthquake frequency near the volcano
B. bulging of the volcano’s slopes
C. increased emission of sulfur and carbon-rich gases
D. All of the above.
E. None of the above.

21. A. magma; water B. magma; oil C. coal; steam D. uranium; water
20. Geothermal energy requires the presence of _____ and in the shallow crust (100s to 1000s m deep)?
A. magma; water
B. magma; oil
C. coal; steam
D. uranium; water