Section: Volcanic Eruptions
Circle the letter of the best answer for each question.
1. What is the name of the molten rock inside a
volcano?
a. pressure
b. ash
c. magma
d. lava
2. What is magma that flows onto the Earth’s
surface called?
a. lava
b. magma
c. ash
d. rock
3. What are the areas on top of the Earth where
magma and volcanic gases come out?
a. air holes
b. meteor craters
c. geysers
d. volcanoes
Nonexplosive Eruptions
4. Which of the following can happen during
nonexplosive eruptions?
a. violent explosions
b. tons of rock blasted into the air
c. huge lava flows
d. fire shooting into the air
Directed Reading B continued
Explosive Eruptions
Circle
the letter of the best answer for each question.
5. Which of the following can happen during an
explosive volcanic eruption?
a. calm lava flows
b. hot debris, ash, and gas shooting into the air
c. a rainbow
d. lava fountains
6. What is ash?
a. flowing lava
b. tiny, dust-sized bits of rock
c. big chunks of rock
d. a gas
What Is Inside a Volcano?
7. what is a vent?
a. a magma chamber
b. an eruption
c. a crack in the Earth’s crust
d. an underground volcano
8. Where is a volcano’s magma chamber?
a. at the top of the vent
b. deep underground
c. on the volcano’s slope
d. outside the volcano
Directed Reading B continued
What Makes Up Magma?
Circle
the letter of the best answer for each question.
9. What affects how explosive a volcanic eruption
is?
a. heat
b. amount of lava
c. composition of magma
d. ash
Water and Magma Are an Explosive Combination
10. What is most likely to happen if the water
content of magma ishigh?
a. A nonexplosive eruption will occur.
b. No eruption will occur.
c. Pressure will decrease.
d. An explosive eruption is likely.
Silica-Rich Magma Traps Explosive Gases
11. Which
of the following statements is true?
a. Silica-rich magma has a thin, runny
consistency.
b. Silica-rich magma allows gases to escape
easily.
c. Silica-rich magma causes explosive eruptions.
d. Silica-rich magma causes nonexplosive
eruptions.
What Erupts from a Volcano?
12.What is lava?
a. liquid magma that flows
b. magma that blasts into the air and hardens
c. a mix of gases and water
d. magma that stays underground
Directed Reading B continued
13. What is pyroclastic material?
a. liquid magma that flows
b. magma that bl asts into the air and hardens
c. a mix of gases and water
d. magma that stays underground
Types of Lava
Read the description. Then, draw a line from the dot next to each
description to the matching word.
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14. forms underwater in rounded lumps
15. flows
slowly, like dripping wax
16. has
a brittle, jagged crust
17. cool, stiff lava that forms jumbled heaps
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•
•
•
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a. aa
lava
b. pillow
lava
c. pahoehoe
lava
d. blocky
lava
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Types of Pyroclastic Material
18. large
blobs of magma that harden in the air
19. solid rock blasted out of a volcano
20. glass-like slivers from exploding gas
bubbles
21. pebblelike bits of magma that cool in the
air
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•
•
•
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a. volcanic
blocks
b. volcanic
bombs
c. lapilli
d. volcanic
ash
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Directed Reading B continued
Pyroclastic Flows
Read the words in the box. Read the sentences. Fill in each blank with the word that best completes the
sentence.
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pyroclastic
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temperature
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hurricane
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22. A
very dangerous type of volcanic flow is a(n) ______________________flow.
23. Pyroclastic materials can move faster than
a(n) ______________________.
24. The center of a pyroclastic flow has a very
high .______________________.
_____ 7. rock
deformation that is like a stretched rubber band and leads to earthquakes