Chapter 5

Question 1

The two types of volcanic eruptions

Answer 1

Effusive and Pyroclastic

Question 2

Effusive eruptions

Answer 2

Gentle eruptions that feature lava of low viscosity and silica (mafic). Lava tends to dominate these eruptions. Are common along divergent boundaries and hot spots.

Question 3

Pyroclastic

Answer 3

Violent eruptions. Lava tends to have high viscosity and high levels of silica. Commonly occur at convergent boundaries and hot spots.

Question 4

Flood Basalts

Answer 4

Primarily fissure eruptions that flow in flat layers with mafic lava. Ex: Columbia River Basalts

Question 5

Shield Volcano

Answer 5

Vent eruption but may also have fissure eruptions. Has mafic lava. Extends over a large area and has gentle slopes.

Question 6

Cinder Cones

Answer 6

Mafic lava and pyroclastic rocks. Vent eruptions

Question 7

Composite Volcanos

Answer 7

Primary vent eruptions. Steep slopes. Intermediate to felsic lava. Has violent eruptions. Ex: Mount Rainer, Mount st. Helens

Question 8

Caldera

Answer 8

Central vent. Extremely large, explosive eruption that causes the collapse of the summit into a partially empty magma chamber. Ex: Crater Lake and Yellowstone

Question 9

Pahoehoe

Answer 9

Basaltic lava texture that is smooth and ropey.

Question 10

Aa

Answer 10

Basaltic lava texture that is blocky

Question 11

Pillow lava

Answer 11

Basaltic lava texture that has a spherical shape. Characteristic of underwater volcanic eruptions.

Question 12

Hazards of mafic volcanos

Answer 12

Lava flows destroying property. Volcanic gases, like sulfur dioxide. Flank collapse, a large landslide that could cause a tsunami . In general, not that dangerous.

Question 13

Hazards of felsic volcanos

Answer 13

Tephra fall out, pyroclastic flows, lahars (mudflows), lava flows and gases.

Question 14

Lahars

Answer 14

A type of mudflow that is the result of mountain ice and snow melting during a volcanic eruption.