Volcanos

Question 1

lava

Answer 1

Magma that has emerged from a volcano onto Earth’s surface

Question 2

Shield volcanoes

Answer 2

by far the largest volcanoes. They are common in the Hawaiian Islands and are also found in Iceland and some islands in the Indian Ocean (Figure 8.5, page 257). Shield volcanoes are shaped like a gentle arch, or shield. They are among the tallest mountains on Earth when measured from their base, often located on the ocean floor. Shield

Question 3

Tephra

Answer 3

includes all types of volcanic debris that are explosively ejected from a volcano

Question 4

Composite volcanoes

Answer 4

known for their beautiful cone shape (Figure 8.7). Examples in the United States include Mount St. Helens and Mt. Rainier, both in Washington State. `

Question 5

Volcanic domes

Answer 5

viscous magma with a relatively high silica content (about 70 percent). The common rock type produced by this magma is rhyolite, composed mostly of potassium-and sodium-rich feldspar, quartz, and minor amounts of ferromagnesian minerals. The activity of volcanic domes is mostly explosive, making these volcanoes very dangerous.

Question 6

Cinder cones

Answer 6

relatively small volcanoes formed from tephra, mostly volcanic ash and larger particles, including volcanic bombs. Bombs are formed from blobs of ejected lava that spin in the air and take on a rounded shape with tapered ends`

Question 7

Craters

Answer 7

Depressions commonly found at the top of volcanoes Craters form by explosion or collapse of the upper portion of the volcanic cone and may be flat floored or funnel shaped.

Question 8

Calderas

Answer 8

gigantic, often circular, depressions resulting from explosive ejection of magma and subsequent collapse of the upper portion of the volcanic cone.

Question 9

caldera eruptions

Answer 9

Relatively infrequent large volcanic eruption that is associated with a catastrophic explosion that may produce a very large volcanic crater 30 or more kilometers in diameter.

Question 10

Lava flows

Answer 10

result when magma reaches the surface and overflows the crater or a volcanic vent along the flanks of the volcano.

Question 11

Pyroclastic activity

Answer 11

describes explosive volcanism, in which tephra is physically blown from a volcanic vent into the atmosphere

Question 12

ash fall

Answer 12

a tremendous quantity of rock fragments, natural glass fragments, and gas is blown high into the air by explosions from the volcano

Question 13

Lateral blasts

Answer 13

explosions of gas and ash from the side of a volcano that destroy part of the mountain.

Question 14

volcanic crisis

Answer 14

a situation in which the science suggests that a volcanic eruption is likely in the near future.