Reading Assessment 5: Volcanoes

There has never been a globally catastrophic volcanic eruption from Iceland's volcanoes, which only involve gentle lava flows.

False

Volcanoes associated with high viscosity magma are usually less dangerous than those with more freely flowing magma.

False

What is the best reason why most lava flows aren't a threat to human life?

Lava flows usually don't flow very quickly, so people can outrun them.

Which of the following is NOT a reason why people live near volcanoes?

Local zoning laws require some people to live near volcanoes.

Why are so many volcanoes found on the Ring of Fire around the margin of the Pacific Ocean?

Many subduction zones occur there.

Several communities around Mt. Rainier are built on enormous, but ancient lahar deposits. What might people in these areas expect if another eruption occurs?

Their homes may be destroyed by a new lahar.

Heat from volcanic areas can be used to generate electrical power.

True

If a basaltic lava flow were coming toward you, you could probably outrun it.

True

Volcanic eruptions can cause tsunamis.

True

Where does tephra come from?

Volcanic rock and lava blasted into the air or carried by gases.

How might a volcanic eruption contribute to climate change?

Volcanoes can send large amounts of fine-grained ash and sulfuric acid aerosols into the atmosphere, potentially causing global cooling.

What is a pyroclastic flow?

A fast-moving avalanche of hot rock, ash and glass fragments

Where are the majority of the active volcanoes in the United States?

Alaska

Where is the majority of lava extruded?

At divergent plate boundaries

Which of the following lists magma types in order of increasing viscosity (LEAST viscous first)?

Basaltic, andesitic, rhyolitic

Which of the following is FALSE about caldera eruptions?

Caldera eruptions result in towering volcanic mountains.

What is the difference between a crater and a caldera?

Calderas are formed from explosions while craters are formed from inward collapse of volcano tops.

What type of volcano structure is composed mostly of pyroclastic debris?

Cinder cone

Which of the following sources of data would NOT be useful in determining whether a volcanic eruption is imminent?

Decrease in atmospheric pressure

Which is NOT a location where volcanoes are found?

Delaware

If a volcanic eruption is predicted for your area, what is the best course of action?

Evacuate

In which two environments are shield volcanoes found?

Hotspots in the ocean and divergent plate boundaries

In which of the following environments would you find the most explosive volcanoes?

Hotspots on land

Which of the following was NOT a hazard associated with the explosion of Mt. St. Helens?

Lava flows that built up the north side of the volcano

Which of following effects might be seen in a volcanically active area even if a volcano does NOT actually erupt?

Landslides and poisonous gases

What is the difference between magma and lava?

Magma is found below the Earth's surface, lava is found on the Earth's surface.

Which of the following is NOT a benefit of volcanoes to the Earth and its inhabitants?

Many of the world's major oil fields are in volcanic rock.

Do humans affect the frequency or size of volcanic eruptions?

No. People do not increase or decrease the likelihood of volcanic eruptions.

Where is the best place to be during a pyroclastic flow?

Nowhere is safe during a pyroclastic flow.

Which of the following volcanic hazards is responsible for the most deaths?

Pyroclastic flows

Mauna Loa in Hawaii is an example of which type of volcano?

Shield volcano

A very large volcano with gentle slopes is a ________ , which is comprised of ________.

Shield volcano...lava flows

What type of volcano structure evolves from layers of pyroclastic debris and lava flows?

Stratovolcano

Which of the following is FALSE about magma?

Tectonic plates move around on an underground ocean of magma.

Which of the following is NOT a reason why stratovolcanoes are dangerous?

They erupt fast-moving lava flows that kill many people.

In which of the following tectonic plate settings are volcanoes typically NOT found?

Transform fault

The disaster at Lake Nyos in Cameroon (Africa) is thought to have been caused by a

a suffocating cloud of invisible volcanic gas.