Chapter 12 - volcanoes

In which location would you most likely find volcanoes?

• far from plate boundaries

• along transform boundaries

• where two continental plates collide

• along mid-ocean ridges and where a plate is subducted

Before lava reaches the surface, the molten material is called

• rock.

• magma.

• volcanic ash.

• liquid fire.

The main factor that accounts for the difference between quiet and explosive volcanic eruptions is

• the size of the volcano’s magma chamber.

• the iron content of the magma.

• the age of the volcano.

• the silica content of the magma.

The main hazard from a quiet volcanic eruption is

• volcanic gases.

• lava flows.

• geysers.

• pyroclastic flows.

What provides the force that causes magma to erupt to the surface?

• the silica in the magma

• dissolved gases trapped in the magma

• gravity in the lithosphere

• the density of the magma

If geologists detect many small earthquakes in the area near a volcano, what can they infer about the volcano?

• It is dormant.

• It is probably about to erupt.

• It is extinct.

• It is a good source of geothermal energy.

Tall, cone-shaped mountains in which layers of lava alternate with layers of ash are called

• shield volcanoes.

• cinder cone volcanoes.

• composite volcanoes.

• lava plateaus.

When many layers of thin, runny lava build up a high, level area, the result is a

• lava plateau.

• shield volcano.

• cinder cone volcano.

• composite volcano.

The huge hole left by the collapse of a volcanic mountain is called a

• lava plateau.

• caldera.

• cinder cone.

• shield volcano.

When magma hardens in a volcano’s pipe, the result will eventually be a landform called a

• batholith.

• dike.

• volcanic neck.

• sill.