Chapter 13

Question 1

a volcanically active area of Earth’s surface, commonly far from a tectonic plate boundary.

Answer 1

Hot spot

Question 2

Oceanic volcanoes that commonly form from mafic magma, which has a low viscosity the gases can easily escape .

Answer 2

Quiet Eruption

Question 3

liquid rock produced under Earth’s surface.

Answer 3

Magma

Question 4

Rock that forms when magma cools .

Answer 4

Igneous Rock

Question 5

are continental volcanoes and have felsic lava which also contains large amounts of trapped gases.

Answer 5

Explosive eruption

Question 6

fragments of rock that form during a volcanic eruption.

Answer 6

Pyroclastic Material

Question 7

magma that flows onto Earth’s surface; the rock that forms when lava cools and solidifies.

Answer 7

Lava

Question 8

Large pyroclastic particles that are less than 64 mm in diameter.

Answer 8

Lapilli

Question 9

large formations of igneous rock.

Answer 9

Pluton

Question 10

forms when magma cools quickly from an underwater volcano.

Answer 10

Pillow lava

Question 11

describes magma or igneous rock that is rich in feldspar and silica and that is generally light in color.

Answer 11

Felsic magma

Question 12

describes magma or igneous rock that is rich in magnesium and iron and that is generally dark in color.

Answer 12

Mafic magma

Question 13

Volcanic ash that is less than 0.25 mm in diameter.

Answer 13

Volcanic dust

Question 14

If the lava continues to flow after the crust forms, the crust wrinkles to form a volcanic rock.

Answer 14

Pahoehoe

Question 15

large, circular depression that forms when the magma chamber below a volcano partially empties and causes the ground above to sink

Answer 15

Caldera

Question 16

Under what conditions does rock melt?

Answer 16

If the temp rises above melting point,if pressure is removed from rock, and if fluids are added.

Question 17

What are the major volcanic areas ?

Answer 17

Subduction zones, mid-ocean ridges and hotspots.

Question 18

What are the signals of a volcanic eruption?

Answer 18

Changes in earthquake activity, bulges on the side of the volcano, and a change in the amount of composition of volcanic gases.

Question 19

What type of eruption was Mt. St. Helens ?

Answer 19

Explosive

Question 20

How was Iceland formed ?

Answer 20

When an island was cut into two parts by a fissure

Question 21

Explain how igneous rock forms .

Answer 21

When magma cools.

Question 22

How do most island volcanoes, such as those in Hawaii, form?

Answer 22

From Mafic magma in the the oceanic volcanoes.

Question 23

List the five major types of pyroclastic material, in order of size,from smallest to largest.

Answer 23

Volcanic ash, volcanic dust, lapilli, volcanic bombs, volcanic blocks.

Question 24

any activity that includes the movement of magma toward or onto Earth’s surface.

Answer 24

Volcanism