GEOL 1001 Chapter 6

The eruption that occurred on Mount St. Helens was triggered by A. a huge landslide, caused a lateral blast that knocked down trees and buildings. B. a fast-moving, viscous lava flow flowed through the middle of Portland. C. a volcano that was so heavy that it caused part of the island to collapse. D. a scoria cone that sent up a large column of pyroclastic material. E. None of these choices are correct.

A

What is a main hazard of this type of volcano? A. relatively small pyroclastic eruptions caused by localized explosions or collapse B. hot molten fragments thrown a short distance from the volcano C. destruction by moderately fluid lava flows that can flow far from the volcano D. viscous lava that moves too fast for people to outrun

A

Which of the following is NOT a characteristic of an actively erupting volcano? A. totally covered in a fresh blanket of clean, white snow B. billowing ash column rising into the sky C. glowing lava flows moving down mountain slopes D. rapidly melting glaciers/snowpack producing massive mudflows

A

Which of the following is NOT true about shield volcanoes in the landscape? A. They are large mountains with steep slopes. B. They can construct some of the world's largest volcanoes. C. They can be large or small. D. All of these choices are correct.

A

Which of the following is least likely to be a volcano? A. a hill capped by volcanic rocks B. a vent where magma and other volcanic material is erupted C. a fissure that erupts hot, molten lava D. a mountain that erupts only volcanic ash E. a hill with a crater formed at the site of an eruption

A

Changes in topography, water chemistry, and gas output all are used to help predict A. harmonic tremors. B. volcanic eruptions. C. mudflows. D. landslides.

B

Long, thin lava flows are typically produced by A. collapsing eruption columns. B. low-viscosity lavas. C. high-viscosity lavas. D. volatile-rich eruptions.

B

Steep-sided hills of viscous lava that pile up over volcanic vents are known as A. scoria cones. B. volcanic domes. C. composite volcanoes.

B

Volcanic eruptions can produce huge floods by A. erupting huge quantities of water vapor. B. melting ice sheets. C. displacing water in lakes.

B

What type of volcanic eruption is probably shown in this photograph? A. fire fountain B. basaltic lava flow C. pyroclastic flow D. caldera eruption E. felsic lava flow

B

When basaltic lava reaches the ocean it A. causes lava fountains at the vent on land. B. forms pillow basalts. C. can flow long distances on top of the water. D. forms circular calderas. E. All of these choices are correct.

B

Which of the following best describes the temperature of materials typically erupted from volcanoes? A. cool to cold B. extremely hot C. warm to slighty hot

B

Volcanic mudflows (lahars) are common on composite volcanoes because A. such volcanoes form preferentially in rainy tropical locations. B. hot mud commonly erupts from their central craters. C. large amounts of rain and snowmelt mix with loose ash on steep slopes.

C

Composite volcanoes are so called because they A. are a combination of shield volcanoes, scoria cones, and other volcanoes. B. have many different types of geologic hazards. C. were first discovered on the island of Composita in Italy. D. are composed of lava flows, pyroclastic material, and mudflows. E. None of these choices are correct.

D

The main hazard of an eruption that forms a large caldera is A. destruction by moderately fluid lava flows that can flow far from the volcano. B. hot fragments thrown a short distance from the volcano. C. volcanic mudflows and landslides. D. burning, building collapse, and suffocation from an eruption column and pyroclastic flows.

D

The typical form for a composite volcano is a A. shallowly sloping shield. B. steep-sided dome. C. broad, circular crater. D. steep-sided cone.

D

This volcano is relatively small and composed of volcanic cinders. What kind of volcano is it? A. composite volcano B. caldera C. volcanic dome D. scoria cone E. shield volcano

D

What is a main hazard of this type of volcano? A. destruction by viscous lava flows that can flow far from the volcano B. volcanic mudflows and landslides C. burning, building collapse, and suffocation from widely distributed pyroclastic material D. relatively small pyroclastic eruptions caused by localized explosions or collapse E. hot fragments thrown a short distance from the volcano

E

What is a main hazard of this type of volcano? A. relatively small pyroclastic eruptions caused by localized explosions or collapse B. volcanic mudflows and landslides C. hot fragments thrown a short distance from the volcano D. burning, building collapse, and suffocation from widely distributed pyroclastic material E. destruction by moderately fluid lava flows that can flow far from the volcano

E

What types of rocks would be common in a composite volcano? A. felsic and intermediate lava flows B. pyroclastic rocks from an eruption column C. pyroclastic rocks from pyroclastic flows D. rocks with fragments formed by landslides and mudflows E. All of these choices are correct.

E