Download DR 9.3a: Causes of Volcanic Eruptions

Name
Class
Date
DR 9.3a: Causes of Volcanic Eruptions
1. To help predict eruptions, scientists study
coming
from active volcanoes and look for changes in the volcano’s ______________.
THE FORMATION OF MAGMA
2. The rock of the Earth’s mantle
a. flows very quickly.
b. has a puttylike consistency.
c. is cooler than the Earth’s crust.
d. is solid and rock-hard.
3. Rock usually melts to form magma
a. when there is an increase in pressure.
b. when there is a decrease in pressure.
c. when there is a decrease in temperature.
d. when it is in a volcano.
4. Magma forms in the deeper regions of the Earth’s
and the uppermost layers of the
5. Changes in
.
and
cause magma to form.
6. How does magma behave like air bubbles in a jar of honey?
WHERE VOLCANOES FORM
7. About 80% of active volcanoes on land form where plates
a. join.
c. collide.
b. separate.
d. slide past each other.
8. Tectonic plate boundaries are areas where tectonic plates
,
, or
.
9. Why are plate boundaries surrounding the Pacific Ocean called the Ring of Fire?
WHEN TECTONIC PLATES SEPARATE
10. A set of rifts between separating plates is called a(n)
a. divergent boundary.
c. crater column.
b. mantle rock.
d. rift zone.
11. Tectonic plates separate at a(n)
boundary.
Name
Class
Date
Place the following steps of mid-ocean ridge formation in the correct order.
12. Magma rises to the surface of the surrounding rock.
13. Mantle material rises to fill the spaces between plates.
14. The magma forms a new crust on the ocean floor.
15. A rift forms as tectonic plates move apart.
16. The mantle rock melts because of the decrease in pressure.
WHEN TECTONIC PLATES COLLIDE
17. Subduction is
a. the movement
b. the movement
c. the movement
d. the movement
of
of
of
of
one tectonic plate against another.
one tectonic plate over another.
one tectonic plate under another.
one tectonic plate away from another.
18. Convergent boundaries commonly exist where
a. tectonic plates move side by side.
b. oceanic crust moves away from continental crust.
c. continental crust is subducted under oceanic crust.
d. tectonic plates collide with each other.
19. As the ocean crust sinks deeper into the mantle,
a. it increases in temperature.
b. it forms a lava fountain.
c. it forms a volcano.
d. its pressure decreases.
20. The oceanic crust is
and
HOT SPOTS
21. The Hawaiian Islands are located
a. along a tectonic plate boundary.
b. far from any plate boundary.
c. over a lava fountain.
d. on lava plateaus.
22. What are hot spots?
23. Some scientists believe that hot spots form along
in the Earth’s crust.
than the continental crust.
Name
Class
Date
PREDICTING VOLCANIC ERUPTIONS
Match each volcano type listed on the right with the correct description listed on
the left. You may use the volcanoes listed on the right more than once.
24. have not erupted in thousands of years
25. have not erupted recently
26. are erupting now
27. probably won’t erupt again
a. active volcano
b. dormant volcano
c. extinct volcano
28. will probably erupt sometime in the future
29. will probably erupt in the near future
30. Before eruptions, the number and intensity of small earthquakes ____________.
31. Changes in the ratio of sulfur dioxide to carbon dioxide may indicate changes
in the
below.
32. Small changes in a volcano’s slope can be detected by a(n)
33. What are three ways scientists predict volcanic explosions?
34. What might cause a bulge in the slope of a volcano?
.